Lesson 1 to 10

A.    - BRIEFING (02,00 h - Total 02,00 h)   

This first lesson involves no flying. It is merely a first, or at least a more comprehensive acquaintance with your instructor, with your home base and with your training aircraft. The lesson will normally begin with an interview during which the instructor will ensure that he is in possession your personal data, such as your address, your telephone number, the number of your training licence, its ultimate date of validity, etc. He will also need a number of additional details such as your age, your previous education, your occupation, etc, all matters which are likely to influence your training progress, and more particularly whether you have already some previous flying experience.   

The training program will be reviewed as well as a number of items which are discussed in the introduction of this manual, particularly the causes which might positively or adversely affect your progress.   

Remember that your present training licence is part of the documents which, by law, must be on board of the aircraft (at least before your first solo flight). Furthermore, and although this document not required to be on board, you must also bring along your personal log-book, as it must be filled in after each flight and must be endorsed by your instructor.   

Your homebase and its particularities

Assuming that your home base is located at a major airport, your instructor will provide you with a detailed planview of the premises (such planview is not always available for small privately owned airfields). It usually includes the following information:
   
1°) The airport's name together with its so-called ICAO four-letter code, for instance Antwerp-Deurne with its code EBAW. Note that the ICAO code for Belgian airfields always begins with the letters EB: Brussels-National is EBBR, Ostend is EBOS, Charleroi is EBCI, Liège is EBLG, etc.
       
ICAO stands for International Civil Aviation Organization. This institution, with headquarters in Montreal (Canada), is a subsidiary of the United Nations. The goals of the ICAO are multiple and fall outside the scope of the present course. Suffice it to note that, amongst other things, the ICAO establishes general regulations regarding international civil air transportation. These regulations must then be adapted and applied in each participating country by a local governmental institution which, for Belgium, is the Belgian Civil Aviation Authority (BCAA), i. e. the "Bestuur der Luchtvaart/Administration de l'Aéronautique", itself a subsidiary of the Ministry of Communications. Until very recently a separate Administration known as the "Regie der Luchtwegen (RLW) /Régie des voies Aériennes (RVA)” took care of the management of all State operated airports as well as of the training of air traffic controllers. However, with the implementation of the political so-called St Michael Agreement (St-Michiels Akkoord/Accord St-Michel), the RLW/RVA is now replaced by two different bodies: on the one hand BELGOCONTROL in charge of the air traffic control within Belgian airspace below FL 240 (±24000 feet, above which ATC, i.e. Air Traffic Control carried out , is by EUROCONTROL, based in Maastricht) and the associated training of its agents, on the other hand BIAC (Brussels International Airport Company), a joint-stock company (NV/SA) which is in charge of the commercial management of Brussels­National airport. As far as the commercial management of regional airports is concerned, this is nowadays the responsibility of the so-called Regions (Gewesten/Régions).   

Another recent development is the creation of the Joint Aviation Authorities (JAA) and the resulting Joint Aviation Requirements (JAR's). The JAA, whose headquarters are located in Hoofddorp, near Amsterdam (Netherlands) is issued from the European Civil Aviation Conference (ECAC) back in 1964, and represents a number of European countries. Its purpose is to review and update the ICAO requirements, to reach a harmonization of flight crew licences within Europe, to eliminate the need for validation of licences delivered by Member States and, in the end, to allow free exchange of flight crew between those States. In fact, the BCAA, is nowadays more directly involved with the JAA than with ICAO. None the less, although a number of things might change in a relatively near future, many regulations, and particularly airport markings and signals are still typically ICAO to this day. (1999) and will probably remain current in the future.

2°) Besides the location of the various airport buildings, aircraft parking areas etc, the planview shows the taxiways and the runways. The runways are shown with their orientation and length. Note that the runway orientation is indicated by two ciphers at each end, for instance 29 and 11 in Antwerp-Deurne. This means that runway 29 is oriented at 290° (rounded off) in relation to the (magnetic) North, whereas it’s opposite is oriented at 110°. Runway 07-25 in Charleroi stands for 070° and 250° If parallel runways exist, they will be marked L (left), C (center) or R (right) in addition to their orientation. This is the case in Brussels-National with runways 25L and 25R, their respective opposites being 07R and 07L. Note that the runway orientation is also indicated by large white ciphers painted on the surface of the threshold. Note also that the active runway is often indicated outside the control tower, if any, by the associated black on a yellow background.   

3°) Many planviews show the so-called ARP, or Airport Reference Point; the official location and elevation of the airfield is referred to this spot.   

4°) The location of the so-called signal area. This, in fact, is a remainder of the "good old times" when radiocommunications were rare, or even totally inexistent. Although it is a piece of antiquity more than anything else on major airports where it tends to disappear, it still has its importance on smaller airfields where radiocommunications are not compulsory. At the end of this lesson you will find the various possible signals within this signal area together with their meaning, as well as other typical signals or markings which can be found at other locations. Note that all these are international ICAO designs. The famous windsock is usually to be found in the vicinity of the signal area: it shows both the wind direction and provides an approximate value of the wind velocity (assuming a correct calibration, when it is horizontal it shows a wind velocity of 15 knots, or 28 km/h).   

Your instructor will show you the exact location of your home base on an aeronautical chart, together with the most important landmarks in its surroundings, possible significant obstacles, location of training areas and any other relevant matters.
   
Assuming that there is a control tower at your home base, your instructor will show you upstairs and introduce you to the air traffic controllers on duty, and give you a rapid survey of the tasks of these persons which incidentally are all BELGOCONTROL personnel. Note that, upon prior request, you are always most welcome in the control tower at your home base, as well as in the ATC facilities at Brussels-National airport. In fact, several visits are even strongly recommended in order to get acquainted with the terminology of radiocommunications. Furthermore, such visits will make you more aware of the extremely high level of responsibilities of the ATC controllers.   

Your instructor will also show you the so-called "Met Office”, if any. This is where you can obtain weather information such as METAR's, i.e. the actual weather conditions at any specific major, regional or military airport, TAF's (Terminal Area Forecast), i.e. the weather forecast for those same airports. Both   METAR's and TAF's are provided in a coded form, but are easily understandable with some habit: your instructor will “translate" some for you as an example. Another possible type of message is the so-called SIGMET, short for “Significant Meteo”. SIGMET's are warnings for weather conditions which involve a potential danger for air traffic, such as thunderstorm activity, fog, icing conditions, unusual strong surface winds or turbulence, etc. Additional available information are the so-called synoptic or prognostic charts showing the current and probable evolution of the weather situation in a specified area, as well as the upper air charts showing the wind direction and velocity, as well as the air temperature at various cruising altitudes. All these information are often presented in a so-called "met folder" which includes the explanation of the various symbols used on weather charts. If possible, your instructor will provide you with such a folder for further study. At any rate, the full explanation of these matters is given during the groundcourses. Keep in mind that the met office must normally be consulted before each flight, but particularly when navigation to another destination is involved. Assuming that no such facility is available at your home base, the necessary information must be obtained by telephone from the nearest aeronautical meteorological station or, even better, from the meteorological center in Brussels-National (tel.: 02/7224356 or 02/7224219).   

You will also be introduced to the AIS, or Airport Information Service, if any. This office is typical for major and regional airports, and is signalled by a black C and/or the letters AIS in black on a yellow background: here you can obtain any required aeronautical information for Belgium or abroad (at least for the surrounding countries) by requesting the official AlP's, or Air Information Publication. There is an AlP for each country. In the AIS, you will also find NOTAM's, i.e. Notices to Airmen: these are information of temporary nature related to air traffic such as unserviceable navigation aids, location of glider or parachuting activities, activation of danger areas, etc. The AIS must be informed previous to and after each flight and, when required, must be provided with a copy of the so-called ATC flight-plan before departure. Your instructor will also provide you with such a copy for further study. Finally, it is also at the AIS that landing and parking fees are to be paid. If no AIS is available at your home base it will be replaced by another office with reduced service capabilities but basically with the same purpose.   
Possible required flight-plans must then be telephoned or faxed to the nearest official ATC facility.   

Depending on the importance of your home base, additional services such as fire brigade, police, customs, first-aid, etc, may be available.   

Your training aircraft

Following this first acquaintance with your home base and the various offices and services which you will or might be involved with, your instructor will finally introduce you to your training aircraft.   

The Pilot Operating Handbook (POH) which you have been provided with is somewhat the equivalent of your car handbook. Although the major part of its contents will automatically be discussed during the elementary training, some matters will be brought to your attention via the various questionaries. At any rate, it is expected that you will know your training aircraft thoroughly before your first solo navigation flight. You will often have to refer to the POH and, as far as this preliminary lesson is concerned, you will already discover a number of general specifications.   

To begin with, you will notice the letters on the fuselage and on the wings: these are the markings of the aircraft, somewhat the same as the identification plate on your car. These markings must be in conformity with the legal policy regarding location and dimensions. The first two letters (or sometimes a cipher and a letter) identify the country of origin: for Belgium, these letters are 00, for Netherlands PH, for Denmark OY, etc . . . For some countries only one letter is used: for France F, for England G, for Germany D, for Italy I, etc. The serie of letters which follows the connecting link is the national registration of the aircraft. The total number of letters is usually five, i.e. two letters for the country and three registration letters, e.g. OO-ABC, or one letter for the country and four registration letters, e.g. G-ABCD. American registered aircraft feature the letter N followed by a number of letters without connecting link.   

 
You will be shown some of the essential parts of the aircraft with their correct denomination (fig. 1):
   
- the fuselage (romp/fuselage)   
- the wings (vleugels/ailes)   
- the horizontal and vertical tailplanes   
  (horizontaal en verticaal kiel- of staartvlak/plan fixe horizontal et plan fixe  
  vertical)   
- the ailerons (rolroeren/ailerons)   
- the elevator (hoogteroer/gouvernail de profondeur)   
- the rudder (richtingsroer/gouvenail de direction)   
- the trim surface (trimvlak/flettner au trim)   
- the flaps (vleugelkleppen/volets hypersustentateurs) as well as slots and  
  slats (spleten en ????/fentes et becs de bord d'attaque), if any   
- the engine, the propeller and its dome (motor, schroef en naafkap/moteur, 
  hélice et casserole)   
- landing gear (landingstel/train d'atterrissage)   

Elementary training aircraft are powered by one single engine and are mostly fitted with a fixed landing gear (a retractable landing gear being more appropriate for advanced high performance aeroplanes). Depending on the aircraft design, the landing gear includes either a nosewheel as shown in fig. l, in which case it is referred to as a tricycle landing gear, or a tailwheel, in which case it is known as a conventional landing gear. The advantages of the tricycle system are firstly that steering on the ground is usually easier, the forward view on some tailwheel types being completely obstructed by the aircraft's nose, secondly, as we shall see later, the takeoff procedure in particular is less critical, which is in fact the reason why the tricycle landing gear was definitively introduced during WWII. On the other hand, and especially for a fixed gear, more drag is produced which tends to curtail performances.   

Most aircraft nowadays are monoplanes (ééndekkers/monoplans), i.e. they are fitted with only one pair of wings. Although biplane (tweedekker/biplan) designs are still produced for some aerobatic models, these are mostly found on vintage aircraft such as the Tiger-Moth or the SV4.   

As far as monoplanes are concerned, the wings can be mounted on the lower, mid or upper part of the fuselage: one talks then respectively of a low wing (laagdekker/aile basse), a medium wing (middendekker/aile médiane) or a high wing design (hoogdekker/aile haute). The wings structure can be cantilever (vrijdragend/en porte-à-faux), i.e. without the presence of struts (steunbalken/haubans): this method is the most usual on low or medium wing aircraft. High wing aircraft mostly feature a strut on each side: this is known as a semi-cantilever structure and is also referred to as a braced wing (ondersteunde vleugel/aile hauban née). The presence or absence of struts (fig.2) is a problem of structural nature: it is simply two different ways to absorb the aerodynamic forces on the wings during flight.   

Most elementary trainers are fitted with an electric system. It is composed of a battery feeding users such as the engine starter, the radio equipment, the lighting system, and any other electrically powered device. Of course, the battery needs to be constantly recharged: this is the purpose of a generator which is most usually driven by the engine.   

You may also expect some explanations regarding the use of the so-called towbar (trekhaak/crochet de remorquage). Its purpose is to push or pull the aircraft in and out of the hangar, or any time it must be moved with the engine shut down. YOU SHOULD NOT USE THE PROPELLER TO THESE PURPOSES !!! Furthermore, A PROPELLER MAY NEVER BE TURNED BY HAND WITHOUT A NUMBER OF SAFETY MEASURES.   
More about this in lesson 02.   

And, talking about propellers, ALWAYS BE EXTREMELY CAREFUL WHEN WALKING IN THE VICINITY OF AN AIRCRAFT AT STANDSTILL BUT WITH ENGINE(S) RUNNING: IN THE PAST. ALL TOO MANY PEOPLE HAVE BEEN HACKED TO PIECES BY WALKING INADVERTENTLY STRAIGHT INTO THE PROPELLER DISC!!! In this concern, BE PARTICULARLY ON GUARD IF YOU HAPPEN TO BE ACCOMPANIED BY CHILDREN!!!!

Manoeuvring the aircraft in and out of the hangar must be carried out with utmost carefulness to avoid damage. Be especially watchful that wingtips and tailplanes don't hit a wall or another aircraft. Once again, USE A TOWBAR (at least if there is one available, which unfortunately is not always the case). Be aware that pushing and pulling an aircraft anywhere causes abnormal forces on the structure and gives way to early appearance of the very dangerous phenomenon of metal fatigue.   

Most aircraft are fitted with tie-down rings (vastleggingsringen/anneaux d'amarrage). Such rings are usually located under each wing and, at least for nosewheel aircraft, under the tail. The purpose of these rings is to tie the aircraft on the ground by means of ropes when it must be parked for several days outside a hangar, as a safety against possible high winds. Note that the ropes may never be tightly fastened but must always have a definite slack: failing this precaution, the tension of already stretched ropes increases even more as a result of possible rainfall and may lead to very serious damage.   

Your instructor will now invite you to take the pilot’s seat in order to acquaint yourself somewhat with this new environment. He will provide you with a rapid view of the flight control system (which is duplicated), i.e. the control wheel or stick (stuurwiel of stuurknuppel/volant ou manche à balai) and the rudder pedals (voetenstuur/palonnier), as well as of the various instrument, handles and switches. One piece of advice: in the future, whenever you have the possibility, and as long as you are not completely acquainted with the aircraft, do not hesitate to install yourself in the PILOT's seat and to particularly study the markings and graduations of the various instruments.   

Answer now the following questionary!   

B.    - FLIGHT TRAINING   

Nil.   


C.    - QUESTIONARY    (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)

Note: In this questionary, as well as in all subsequent ones, questions marked (POH) refer to the pilot Operating Hand­book)   

01. - Your pilot licence must be on board each time you fly. True or false ?

02. - Your training licence is valid until ___________

03. - ICAO stands for _____________________________________________________

04. - JAA stands for JAR stands for _________________________________

05. - ICAO is a subsidiary of the _____________ with headquarters in the city of ___________ in ____________

06. - ECAC stand for ____________________________________________________

07. - The ECAC dates back to 19___

08. - The JAA headquarters are located in the town of  ___________________________ near the city of ____________ in  ______________

09. - The ICAO/JAA regulations are adapted and enforced in Belgium by the __________________

10. - The body in charge of the management of the regional Belgian airports is the ____________. For Brussels-National airport it is ___________

11. - The body in charge for the air traffic control in Belgium, as well as for the training of the agents is  _______________

12. - The ICAO four-letter code of your home base is ________

13. - State the orientation(s) of the runway(s) at your home base. What do these ciphers represent ?   

14. - ARP stands for _________________. It represents the official _____________ and ___________ of the airport   

15. - State the meaning of the following signals within the signal area:   

- a yellow cross on a red background   
- a transverse yellow line on a red background   
- a white dumbbell (witte halter/haltère blanc)   
- idem with a black line in each circle   
- a white letter T, or a tetrahedron (viervlak/tétraèdre)   
- a white letter T with associated white disc   
- one black ball hanging on a mast   
- two black balls hanging above each other on a mast   
- an arrow curved to the right   
- a double white cross   

16. - State the meaning of the following signals located outside the signal area:   

- a double yellow cross   
- a white letter H   
- a single white cross   
- a black letter C on yellow background   
- two black ciphers on a yellow background   

17. - AIS stands for ______________________________________________________

18. - What do you understand by a synoptic or prognostic chart ?

19. - The met office can provide you with upper air charts. Which two important information do you find on these ?

20. - What do you understand by:   

- METAR   
- TAF   
- SIGMET   
- NOTAM   

21. - (POH) State the manufacturer and model of your training aircraft.   

22. - (POH) The maximum takeoff weight of your training aircraft is __________ kgs. The maximum landing weight is ___________

 
23. - (POH) State, for your training aircraft, the following values in meters:   

- Length ___________
- Wingspan (spanwijdte/envergure) __________
- Height ___________

24. - (POH) The manufacturer of the engine of your training aircraft is ______________ It develops ___________ HP at __________ rpm   

25. - (POH) The engine of your training aircraft has ______ cylinders   

26. - (POH) The propeller of your training aircraft is made of:  ____________ and is manufactured by ___________________

27. - (POH) Amongst the following characteristics, state those which are applicable to your training aircraft:   

- monoplane   
- biplane   
- high wing   
- low wing   
- medium wing   
- cantilever wing structure   
- semi-cantilever wing structure   
- fixed landing gear   
- retractable landing gear   
- tailwheel   
- nosewheel   

28. - State the national identification letters for a Belgian registered aircraft.   

29. - What is the only appropriate means to move an aircraft on the ground with the engine shut down ?

30. - State the purpose of the tie-down rings. Which precaution is required when using these rings ?

 
Translation of terms used in figures

Fig. 1

- Motor: engine/moteur   

- Spinner of naafkap: spinner/casserole d'hélice (" spinner" wordt dikwijls in de vlaamse taal gebruikt)   

- Landingstel: landing gear/train d'atterrissage   

- Romp: fuselage/fuselage   

- Richtingsroer: rudder/gouvernail de direction   

- Verticaal kielvlak: vertical tailplane/plan fixe vertical   

- Trimvlak: trim surface/surface de trim   

- Rolroer: aileron/aileron   

- Vleuqel: wing/aile   

- Flaps of vleugelkleppen: flaps/volets hypersustentateurs (Le mot "flaps" est couramment utilisé en langue française)   

- Horizontaal kiel vlak: horizontal tailplane/plan fixe horizontal   

- Hoogteroer: elevator/gouvernail de profondeur
   
Fig.2

- Semi-cantilever vleugelstructuur: aanwezigheid van steeunbalken   

  Semi-cantilever wing structure: presence of struts   

  Construction d'aile semi-cantilever: présence de haubans   

- Cantilever vleugelstructuur: geen steunbalken (meestal op laag en middendekkers)

  Cantilever wing structure: no struts (generally on low and medium wing aeroplanes)   

 Construction d'aile cantilever: pas de haubans (généralement sur avions à aile basse et aile médiane)   

Signalenpark Signal area - Parc à signaux

- Geel kruis op rode achtergrand: verboden the landen   

  Yellow cross on red background: landing prohibited   

  Croix jaune sur fond rouge: interdiction d'atterrissage   

- Dwarse geel lijn op rode achtergrand: bijzondere voorzichtigheid geboden   

  Yellow tranverse line on red background: special precautions  to be taken   

  Ligne transverse jaune sur fond rouge: précautions specials requises   

- Witte halter: gebruik van banen en taxiwegen is verplicht   

  White dumbbell: use of runways and taxiways is compulsory   

  Haltère blanc: usage obligatoire des pistes et des chemins de   
  taxi   

- Witte halter met zwarte strepen: landen en opstijgen op de banen. Banen en taxiwegen niet verplicht   bij grondbewegingen

  White dumbbell with a black line in discs: landing and takeoff on runways is compulsory. Runways and taxiways are not compulsory for ground movements  

      
  Haltère blanc avec lignes noires: atterrissage et décollage obligatoirement sur les pistes. Les pistes et   les chemins de taxi ne sont pas obligatoires pour les mouvements au sol
   
- Letter T of viervlak: landen en opstijgen in de richting van het kortste been/in de richting van de punt   

  Letter T or tetrahedron: landing and takeoff towards the shortest leg/in the direction of the point   

  Lettre T ou tétraèdre: atterrissage et décollage en direction de la jambe la plus courte/en direction de  la pointe   

- Letter T met schijf. of zwarte bal aan mast: verchilIende start en landingsrichtingen   

  Letter T with disc, or black ball on mast: several directions for takeoff and landing   

  Lettre T avec disque, ou panier noir hissé au mât: plusieurs directions pour décollage et  atterrissage   

- Naar rechts gebogen pijl: circuit naar rechts in voege   

  Arrow curved to the right: right hand circuit   

  Flèche courbée vers la droite: circuit par la droite   

- Dubbel wit kruis. of twee zwarte ballen aan de mast: zweefvluchten aan de gang   

  Double white cross, or to black balls on the mast: glider flying in progress   

  Double croix blanche, ou deux paniers noirs hissés au mât: vols de planeurs en cours   
   
- Dubbel geel kruis: plaats waar sleepkabels worden afgeworpen   

  Double yellow cross: area where towing cables are dropped   

  Double croix jaune: emplacement de larguage de cables de remorquage   

- Witte letter H: landingsplaats voor helicopters   

  White letter H: landing area for helicopters   

  Lettre H blanche: aire d'atterrissage pour hélicoptères   

- Wit kruis: onbruikbaar gedeelte   

  White cross: unusable area   

  Croix blanche: aire inutilisable   

- Zwarte C op gele achtergrand: AIS burelen   

  Black C on yellow background:.AIS office   

  C noir sur fond jaune: bureaux AIS   

- Twee zwarte cijfers op gele achtergrand: in gebruik zijnde baan   

  Two black ciphers on yellow background: runway in use   

  Deux chiffres noirs sur fond jaune: piste en service

A.    - BRIEFING (01,00 h. - Total 03,00 h.)   

You were briefly introduced to your training aircraft during the previous lesson. We are now going to study a few things more deeply and, most probably for the first time in your life, you will also fly yourself... 

Let us begin with a few considerations regarding aircraft construction in general. It is often a metal structure whereby light aluminium alloys (aluminium legeringen/alliages d'aluminium) are mostly used in combination with same steel (staal/acier) parts.   
Besides these “all metal" designs, some aircraft feature a fuselage made of steel tubing, whereas the wing and tailplanes construction is made either of metal or wood, the whole structure being covered with linen (linnen/toile). Other designs are integrally made of wood. In fact, a number of combinations is possible. A more recent trend is the use of so-called composites (a sort of plastic) for some parts such as wing tips, engine cowlings and propeller spinners. Nowadays there are even aircraft which are completely built in this material, which allows for some new and less complicated constructional techniques.   

Particularly for "all metal" aircraft, the fuselage can be constructed according to two different methods: the monocoque or the semi-monocoque design (schaal- of semi-schaalstructuur/construction monocoque ou semi-monocoque) :   

- In the monocoque system, the fuselage shape is obtained by a number of skin plate rings (bedekkingsplaatringen/anneaux de revêtement) which are simply riveted to each other, in which case, all forces acting on the structure are absorbed by the exterior plating, which is then referred to as stressed skin (dragende huid/revêtement portant) . This construction method is rather rare and the semi-monocoque structure is usually given preference.   

- The semi-monocoque method consists of a number of bukheads, or formers (spanten/cadres), connected to each other by stringers (langsprofielen/longerons): this assembly forms a frame on which the skin plating is riveted (fig. I). In this system, the forces are mainly absorbed by the frame, and only partly by the skin.   

The engine, usually a horizontally opposed four or six cylinder design, is positioned in a support located in front of the fuselage and which includes a number of rubber vibration absorbers. A firewall separates the engine from the cabin to protect the occupants from the high temperatures developed in the engine compartment as well as from any possible engine fire occurrence, although this latter possibility is extremely remote.   

The wing structure consists usually of two spars (langsliggers/longerons), one main and one auxiliary. Both are connected to the fuselage and run towards the wing tip. These spars, whose purpose is to absorb the up- and downgoing forces during flight, are the major component of the wing. The spars are kept in place by a number of adjoined ribs (ribben/nervures) located at equal distances from each other. The shape of the ribs determines the wing section (fig.2), also referred to as wing profile (vleugel profiel/profil d'aile). The frame of spars and ribs is made of wood or metal and is covered either by linen¡ by wood or by riveted metal plating.   

Some wings are tapered (tapse vorm/forme conique), both in planform as in thickness, i.e. their width as well as their thickness decrease from the wing root towards the wing tip (fig.2 and 3). This is typical for cantilever wing structures whereby strength considerations dictate more thickness at the root where bending forces are the greatest, than at the tip where they are least. This requirement leads to the need to taper the planform as well in order to keep the wing profile unchanged despite its smaller size at the tip (wing sections will be discussed further in lesson 07).   

Another typical feature, particularly for low wing aircraft, is the so-called dihedral (V-vorm/dièdre) whereby the wings feature a slight V-shape (fig.3): this has to do with the aircraft's lateral stability during flight and will be discussed further during the groundcourse. Note that also the tailplanes have a stabilizing function, somewhat like the feathers of an arrow. The structure of these tailplanes, as well as of the flight control surfaces, the flaps and the movable trimming surfaces, is similar to the structure of the wings, albeit of reduced size.   

As far as the flight control surfaces are concerned, you noticed that these are mounted on the wings and on the tailplanes. Now, wings and tailplanes offer a certain degree of elasticity when aerodynamic forces are exerted on them. Although this elasticity is required to absorb these forces, it may convey vibrations to the associated flight controls surfaces, particularly to the ailerons, a phenomenon known as flutter. This is particularly likely to occur at high speeds and/or under heavy aerodynamic load conditions and, once initiated, flutter can rapidly become so severe that the affected flight control surface snaps off before the pilot can do anything about it. Flutter resulted in quite a number of fatal accidents in the early days of aviation, however, its cause was finally identified and definitively eliminated: it turned out that simply adding a lead counterweight (tegengewicht in lood/contrepoids en plomb) on the forward edge of the flight control surfaces, in fact moving their center of gravity close to the hinge axis, completely cured the problem. Nowadays, this counterweight, referred to as mass balance, is usually hidden within the flight control surface's structure, but on some aircraft, mostly vintage designs, it is located on the outside of the surface and is a clearly visible appendant.   

All landing gear wheels are fitted with shock absorbers (schok­dempers/amortisseurs). These are usually of the oleo-pneumatic type, i.e. combining air and oil for mainwheels and nosewheels.   
   
 
Tailwheels are often fitted with simple leaf springs (bladveren/ressorts). Some aircraft, such as the Cessna single engine types, use either a single leaf spring or a tubular spring-steel system for the mainwheels whereas on many vintage light aircraft, such as the Piper-Cub, use is often made of a simple elastic cord.   
The main wheels only are fitted with brakes which are usually of the hydraulically actuated disc type. These are mostly independently operated by depressing the upper part of either the left or right rudder pedal. A parking brake lever allows setting both brakes together.   

Cabin windows must be verified for cleanliness before every flight. However, be aware that they are made of plastic and, if cleaning is required, care should be taken not to use gasoline, alcohol or any other non-approved product which might cause very serious damage: verify the recommendation published in the POH in this concern.   

Despite their seemingly fragile structure, aircraft are extremely robust and reliable. The risk for a structural failure occurring during flight is non existent, and the notorious parachute is completely needless. Of course, this implies that all flight operations are carried out within certain limitations: these will be discussed as the flight training progresses. It also implies that the aircraft is maintained strictly in accordance with the legal schedule and requirements, and that it is provided with a valid Certificate or Airworthiness issued by the BCAA' s technical department. Finally, and not in the least, the pilot must ensure that all safety precautions are taken, not only during flight,   
but on the ground as well, both before and after starting the engine.   

Structural damage is mostly the result of a wingtip or a tailplane hitting a wall, a door, or even worse, another aeroplane while moving the aircraft in or out of the hangar. It can also be the result of a collision with some obstacle while taxiing, of a hard landing, etc. Such incidents may happen to anyone, but the important thing is not to takeoff with a damaged machine, which is plain common sense (and even if the damage seems to be insignificant, have it verified by a mechanic or an instructor). What is more, IF YOU INADVERTANTLY CAUSED THE DAMAGE YOURSELF NEVER FAIL TO NOTIFY WHOEVER MIGHT BE CONCERNED.

At any rate, before starting the engine, the pilot must submit his aircraft to a so-called preflight external inspection which must be carried out in accordance with the instructions laid down in the POH. For this first flight, your instructor will perform and comment this inspection so that you should be able to do it yourself as from lesson 03.   

 
Unless it was demonstrated during the previous lesson, the instructor will show you the mechanism of the flight control system:   

a)     The control wheel (on some aircraft it is rather a stick, and "stick" is the commonly used term for the control wheel as well) can be moved to the left or to the right. Doing so to the left causes the left aileron to move up and the right aileron to move down. Conversely, moving the stick to the right causes the right aileron to move up and the left aileron to move down.   

b)    The stick can also be moved rearward, which causes the elevator to move up and conversely, pushing the stick forward causes the elevator to move down.   

c)    The rudder pedals (simply referred to as "rudder") actuate the rudder: depressing the left pedal causes the rudder to deflect to the left, depressing the right pedal causes the rudder to deflect to the right. Note that, on most aircraft with nosewheel, the rudder pedals are also connected to this wheel and are used to steer the aircraft on the ground. However, this particularity makes it difficult, if not impossible, to move the rudder pedals when the aircraft is at standstill.
   
Although details about their use will come at a later stage, the instructor will also show you the operation of the flaps, possibly slats and slots, as well as of the trim.

Just as is the case for your car, the law requires a fire extinguisher and a first-aid kit to be on board. As far as light aircraft are concerned, the reason of these tools is somewhat questionable: their presence is more a matter of regulations rather than a very effective part of safety equipment. The first-aid kit is probably intended in anticipation to a highly improbable forced landing outside the airfield boundaries whereby someone might get slightly hurt. As for the fire extinguisher, if its purpose is to extinguish a fire in the cabin (an equally remote possibility) there are other and safer means to do so, the most effective one being to smother the fire by simply covering the flames with a piece of clothing. Indeed, discharging a fire extinguisher during flight in the restricted space of a small aircraft cabin can have very serious consequences, both on account of toxicity as on account of smoke generation. If the idea is to extinguish a fire occurring in the engine during the starting procedure, you will learn later that also such a situation can efficiently be handled otherwise and, in the very unlikely case that things go definitely out of hand, it is doubtful that this small fire extinguisher will be of any use. Anyway, you should know where it is located, how to detach it from its cradle, how to use it and which its limitations are.   

During the external inspection, you will be shown the so-called pitot-static system which operates the three so-called pressure instruments, namely the airspeed indicator (ASI), the altimeter and the vertical speed indicator (VSI), the later (variometer/variomètre) showing the rate at which the aircraft climbs or descends. The pitot-staticsystem consists of an air inlet tube usually located somewhere on a wing and whose opening faces the airflow during flight: this is the dynamic air inlet, usually referred to as pitot tube. It is solely related to the airspeed indicator and can usually be electrically heated against possible icing. Note incidentally that the term "pitot" comes from Henri Pitot (1695-1771), a French scientist who, already in the eighteenth century, studied the behaviour of airflow. The static part consists of air inlets which are either drilled in each side of the pitot tube itself or which are located on either side of the fuselage. The static air inlets are related to all three pressure instruments. The reason why static inlets are located either side is to avoid faulty instrument readings if the aircraft happens to skid sideways during flight. The full study of the pitot-static system and the related indicators is part of the groundcourse. At this stage, simply keep in mind that it is prohibited to blow into the pitot tube as this would almost surely destroy the airspeed indicator. Note also that, whenever the aircraft is parked for an extended period of time, a cover should be installed on the pitot tube to protect it from dust and insects: never forget to verify that it is removed during the external inspection.   

Note that the pressure instruments are normally graduated as follows:   

- The altimeter in feet (voeten/pieds), 1 foot being equal to 0,3048 meters, sometimes in meters. To convert meters in feet, multiply by 3,281.   

- The vertical speed indicator in feet per minute (ft/min), sometimes in meters per second (500 ft/min equals ±2,5 m/s).   

- The airspeed indicator in knots (kts), or in miles per hour (mph), often in both units; and sometimes in kilometers per hour. The knot (knoop/noeud) is used to express a speed, 1 knot being equal to 1 nautical mile (zeemijl/mille nautique) per hour (thus, be aware that a speed is simply expressed in knots, never in knots per hour). On the other hand, the nautical mile is the expression of a distance and equals 1852 meters. Knots and nautical miles are nowadays the standard units for aviation purposes. To convert to kilometers to nautical miles, or kilometers per hour to knots, multiply by 0,5396. On the other hand, the mile (mijl/mille), i.e. the statute mile equals 1609 meters and is still currently used to express either a distance (miles) or a speed (miles per hour). However, and only for aviation purposes, the mile and the mile per hour are respectively replaced by the nautical mile and the knot (although some older airspeed indicators are still solely graduated in mph). To convert kilometers to statute miles, multiply by 0,621   
   
As far as flight instruments are concerned, some aircraft are fitted with a so-called venturi tube, i.e. a tube opened on both sides and featuring a narrowing at about the first quarter of its lengtht, aligned with the aircraft's longitudinal axis, and mostly mounted on the lower part of the fuselage. This is an outdated driving system for the gyroscope used in instruments such as the artificial horizon or attitude indicator, the directional gyro and the turn indicator. These three so-called gyroscopic instruments are mainly provided for flying without external references, such as in clouds although they can be very useful at any time, particularly the directional gyro which as we shall see later, offers certain advantages over the basic magnetic compass. These gyroscopic instruments are practically standard equipment on most present day light trainers but they are operated either by means of a so-called vacuum pump (vacuum- pomp/pampe à vide) driven by the engine, or electrically as is usually the case for the turn indicator. At any rate, the detailed study of these instruments is also a part of the groundcourse.   

Read the details regarding the fuel system in the POH. You will note that the fuel capacity is usually mentioned in United States Gallons, or USG. One USG equals 3,785 liters. To convert liters in USG, multiply by 0,264. Be aware that, in the United Kingdom, the local units might be Imperial gallons, or Imp. Gall.: one Imp. Gall. equals 4,546 liters; to convert liters in Imp. Gall.: multiply by 0,22. One of the major items of the external inspection concerns the fuel contents which must obviously be amply sufficient for the intended flight. The fuel contents should be checked visually in each tank by opening the filler cap: NEVER THRUST THE INDICATIONS OF THE FUEL GAUGES IN THE CABIN !!! Another way of preventing problems on account of fuel contents is to note the amount loaded at each refuelling in the aircraft's log-book and to verify the elapsed flight time since then. The fuel tank vents (ontluchting/mise à l'air) must be free to ensure proper fuel feed to the carburettor. Another important matter is to make sure that no water or other contaminant is present in the fuel system. This is done by means of a number of draining valves and the use of a sampler, i.e. a small plastic container, in which fuel can be collected and checked. Draining valves are usually located on the underside of each fuel tank, on the lowest part of the fuel system, and on the so-called fuel strainer, i.e. the filter located between the tanks and the engine carburettor. This check is compulsory before the first flight of the day, or any time that the fuel storage facilities are questionable, particularly on small airfields where the fuel might very well be stored in cans. It is also strongly recommended when the aircraft has been parked in heavy rain: Water in the fuel can only be detected by means of a transparent sampler: if there is, you will clearly notice its presence below the fuel level. Assuming that water, dirt or other contaminants are discovered, the fuel must be repetitively drained until absolutely clear. Note that the fuel must not only be verified for water or contaminants, it must also be of the correct type and colour (see POH).

The POH also provides the information related to the maximum and minimum contents of engine lubrication oil. Your instructor will show you the location of the associated dipstick and how to use it. As far as the engine is concerned, checking the oil is the most important item: this should be done before each engine start. Furthermore, and if at all feasible (which unfortunately is not always a simple operation) it is recommended to open the cowlings and verify the engine for possible oil or fuel leaks, loose wires or accessories, etc. Assuming that the cowlings can easily be opened, your instructor will take this opportunity to show you the main parts of the engine: cylinders, carburettor, magneto's, etc. If this proves unpractical, it might be interesting to visit the maintenance shop to have a look at these various accessories.   

 
You will also be shown the various air intakes related to engine and cabin cooling. One particular intake allows filtered air to be directed to the carburettor: it is usually clearly visible under the engine's main air intakes (although on some aircraft it may be hidden within these intakes), and should always be kept in clean condition. The carburettor and its associated technicalities is described in PILOT NOTE I: “BASIC PRINCIPLES OF LIGHT AIRCRAFT ENGINES", and we strongly recommend you to study it.   

Chances are that the aircraft is equipped with quite some radio-navigation gear and associated antennas besides the basic radio transmitter/receiver. Although all these additional systems are irrelevant at this stage of your training, your instructor will nonetheless summarily describe the purpose of each antenna.
   
As said earlier, the external inspection must be carried out according to the instructions laid down in the POH. Although it is usually not mentioned with so many words, pay particular attention to abnormal wrinkles on the skin of the fuselage and the wings; on “all metal" aircraft, beware of rivets showing a graphite stain: wrinkles and loose rivets may be signs of an internal fracture. As a general rule, watch for missing rivets, missing bolts, cracks, unusual leaks, excessively worn tires, etc. And if in doubt, never hesitate to take advice of an approved mechanic. One last recommendation: perform the external inspection with a suitable rag at hand, and besides ensuring that the windshield is clean, wipe off any single trace of dirt, engine oil or any other fluid on the fuselage, on the landing gear or anywhere else. ALWAYS TREAT ANY AIRCRAFT AS IF IT WERE YOUR OWN PROPERTY !   

Once installed in the pilot’s seat, first thing is to adjust it correctly. A good seating position is extremely important: your outside view may not be blocked and all controls, levers and switches must be within easy reach. The instructor will show you how to use the seat belts and shoulder straps. Note that the seat belts must be kept fastened throughout the flight, whereas shoulder straps, if available (which unfortunately is not always the case), are particularly recommended for takeoff and landing. Shoulder straps, usually a single chest strap as in cars, may feature an inertia reel mechanism whereby they extend or retract with normal body movements, but automatically lock in place if a sharp pull is exerted. It is also essential that you know how to quickly release the straps and open the doors if the aircraft is to be evacuated in a hurry.   

Besides your pilot licence, the law requires a number of documents to be on board. The instructor will show you these, and you should carefully analyze each of them at first opportunity:       

1°) The Certificate of Airworthiness (Luchtvaardigheid Bewijs/Certificat de Navigabilité), whose date of validity must be verified as well;   

2°) The aircraft's Certificate of Registration (Inschrijvingsbewijs/Certificat d'Enregistrment);

3°) The official documents for the technical approval of the radio receiver/transmitter(s);   

4°) The Aircraft's Log-Book (Reisdagboek/Carnet de Route), which must be filled in after each flight;   

5°) The aircraft manual (POH, AOM or Owner's Manual);   

The instructor will now give you a rapid survey of the various indicators, levers, switches, etc. Some items are rather self-explanatory, others will be further discussed as training progresses. Besides the stick, the rudder pedals, the trim system, the flaps system and the flight instruments which were already reviewed previously, the following should be particularly noted:
   
- The carburettor heat control (carburattor verwarrning/réchauffage du carburateur): the carburettor, whose purpose is to mix the outside air with the fuel to form the inflammable mixture which is then directed to the cylinders, it is very easily subject to icing. Icing can rapidly lead to engine power loss and ultimate stoppage, and must immediately be corrected by using hot air. Selecting the carburettor heat to HOT closes the normal carburettor air intake, which you noticed earlier, and allows heated cooling air around the cylinders to feed the carburettor system until the ice has disappeared. The carburettor heat must often be used when flying in high humidity conditions (see PILOT NOTE I for further explanations) . However, be aware that, when the carburettor heating system is in operation, the carburettor air is no longer filtered.   

- The mixture control (mengselregelaar/contrôle de mélange): painted in bright red to avoid embarassing finger trouble, as indeed this lever is used to shut the engine down. It has other uses though, as explained in PILOT NOTE I, but at this stage you simply ought to know that the RICH position (full forward) is used to start the engine, whereas the ICO (Idle Cut-Off, full aft) position shuts the engine down.   

- The throttle lever (gashendel/manette à gaz): is the equivalent of the gas pedal on your car, and controls the engine RPM (Revolutions per Minute - toerental/tours par minute). Pushing it forward increases the RPM, and vice-versa. Although this is usually not the case on elementary trainers, some aircraft may be fitted with an additional propeller control. This is when the engine is fitted with a so-called variable pitch, or constant speed propeller (verstelbare regulateurschroef/hélice à pas variable ou à vitesse constante). This requires some more explanations which can be found in PILOT NOTE II: "THE AIRCRAFT PROPELLER AND ITS EFFECTS". But again, most elementary trainers are fitted with a so-called fixed pitch propeller.   
   
- The magneto switch (magnetoschakelaar/contact magnéto): this is related to the ignition system (ontsteking/allumage) of the engine, or rather to both ignition systems, as there are two independent such systems whose purpose it is to ignite the fuel-air mixture within the cylinders. The magneto switch is usually combined with the engine starter system, in which case five positions are possible: OFF, LEFT (left magneto in operation), RIGHT (right magneto in operation), BOTH (both magnetos in operation, which is the normal position in flight) and START. However, note that the starter might as well be activated by an independent button. The magneto and its technicalities are also fully described in PILOT NOTE I. However, be aware that EVEN WHEN THE MAGNETO SWITCH IS IN "OFF" POSITION. THIS DOES NOT WARRANT THAT THE ENGINE WILL NOT FIRE IF THE PROPELLER IS TURNED ABOUT BY HAND ! In other words, NEVER EVER TURN A PROPELLER BY HAND UNLESS THE FOLLOWING SAFETY MEASURES ARE TAKEN:   

- aircraft outside the hangar   
- magneto switch "OFF"   
- mixture control "ICO"   
- throttle lever on idle (traagloop/ralenti)   
- parking brakes set and/or wheel shocks in place.   

- An electric system is required to supply a number of things such as the engine starter, often the flaps, the various electrical switches and the radio equipment. For further explanations, refer to PILOT NOTE IV: "LIGHT AIRCRAFT ELECTRIC SYSTEM". At this stage, simply be aware that electric power is provided by the battery (whose location the instructor will have shown to you during the external inspection), and that the battery itself must be supplied by a generator or alternator to keep its charge. The generator or alternator is driven by the engine. A red painted master switch allows to switch on the battery, often together with the generator/alternator, and a number of independent switches controls users such as landing lights, navigation lights, pitot heater, cabin lighting, etc. Note also the presence of circuit-breakers and/or fuses, in fact one for each user, and whose purpose it is to protect the various appliances from fire in case of short-circuit. Incidentally, it is recommended to have a closer look at these at first opportunity in order to see which appliances are protected by which circuit-breaker.

Safe flying is for a significant part a matter of carefully following the checklists. You will find one in the POH involving all phases of the flight: external inspection, before and after starting engine, before takeoff, etc. The checklist published in the POH is appropriate for experienced pilots: as many items are considered as common knowledge, it is made as short and as concise as possible. However, this simplification is not always adequate for student pilots, nor for experienced pilots if they fly only once in a while on a specific aircraft type. Therefore, more expanded checklists are often used, particularly with regard to the verifications which must be carried out before takeoff and upon shutting down the engine: you are then literally guided through every single move so that absolutely nothing can be overlooked.   
   
Whichever the checklist in use, it is strongly recommended that you read and review this document completely once in a while. Be aware that a number of checks have to be carried out during flight as well. As far as the verifications on ground are concerned, in the very beginning stages you will read the checklist item by item and verify that things are as required or that proper action is taken. However, this is not the normal way to use a checklist: in fact you must very soon be able to carry out the various verifications and actions by heart, and only then take the checklist at hand and read it item by item to ensure that nothing has been forgotten or overlooked. This method is the most efficient as well as the fastest. Take also the habit to read the checklist loud and clear in the presence of your instructor (or any other pilot) and to clearly point out any item. To obtain fast results, install yourself as often as possible in the pilot's seat when the aircraft is parked, and practice the various checklists: this is known as cockpit-drill.   

Finally, as at this stage you are training in view of a so-called single pilot operation (no co-pilot or any other active crewmember being normally involved), some parts of the checklist must be performed without the help of the written document. This is mainly the case for in-flight verifications for which there is usually a mnemonic available.   

General safety recommendations   

1)    Never fly if you do not feel well due to fatigue, to illness including a cold in the head, or to a simple hangover.

2)    Never fly when you are under the influence of medications such as tranquilizers, sedatives, or any similar drugs.
   
3)    Never fly if you are emotionally upset, as may be the case immediately following an argument.   

4)    Never fly shortly after a session of diving in deep water.   

5)    Never absorb any alcoholic beverage shortly before flying.   

6)    When walking on the apron, always stay well clear of running engines.   

7)    Never turn a propeller by hand without taking the appropriate safety precautions.   

8)    Some engines are not fitted with an electrical starter; so that the propeller must be swinged around by hand in order put it in operation. Never attempt this without having been properly briefed about the applicable procedures.   

9)    Assuming that your engine must be started by hand swinging; never try to start it yourself without a fully qualified person at the controls.

10)    Smoking on apron is usually prohibited. At any rate, never smoke in the vicinity of the fuelling station.   

11)    Although most aircraft cabins are fitted with ashtrays and that ventilation is provided, PILOT and passengers should refrain from smoking in the restricted space of a light aircraft cabin during flight.   

12)    Never take any strongly magnetized objects along in flight, neither in the cabin, nor in the baggage compartment, as these are likely to influence the magnetic compass.   

13)    Lady pilots in particular (ar passengers) should not carry spray boxes (spuitbussen/aérosols) of any sort in their purse (or in their baggage), as these are likely to explode with increasing altitude.   

B.    - FLIGHT TRAINING (Dual 00,45 h. - Total 00,45 h)   

The instructor will now proceed with the engine starting and associated checklist, taxiing the aircraft to the runway, perform the engine check, or run-up, as well as the before takeoff check­list, and comment every move: all you have to do is to listen to what he says and watch his ways of doing. Also listen to radio­ communication: don't worry if you don't understand the messages very well, this will improve rapidly.
   
For anyone who has never been in the air before, this first flight, which should only be carried out in fair weather conditions, is a revelation. It is mainly a sight-seeing flight rather than a truly training session: so, relax and enjoy it! If you feel too hot or too cold, don't hesitate to say so!

Your instructor will point out as many as possible of the landmarks he previously showed you on the chart. Besides, it is a good idea to bring along such a chart for each flight. Look around and, assuming that happen to detect other aircraft in the vicinity, show them!   

The instructor will tell you to take over the flight controls for a little while. Relax! The aircraft flies practically by itself! Keep one hand loosely on the stick, the other one on the throttle lever and the tips of the feet on the lower edge of the rudder pedals: strain-must be avoided at all times! You will then be requested to perform small movements, first with the stick to the left, to the right, forward and aft, then with the rudder pedals to the left and to the right, trying each time to bring the aircraft back in steady horizontal position. By doing so, you will notice that very small inputs of the flight controls give way to rather significant movements of the aircraft.   

 
The instructor will take over again and ask you to read the altitude, the airspeed or the heading: perhaps it will show that you need to get more accustomed to the graduation of these instruments, which is another exercise for cockpit-drill.   

Finally, you will be questioned about the direction in which the airfield is: straight ahead? Behind you? to the left or to the right ? This is not always easy to determine, particularly if there is a lack of clearly recognizable landmarks, and even with them it might still be a little problematic. But here again, don't worry if you are somewhat lost: this is perfectly normal for an initial flying experience !   

On the way back to the airfield, the instructor will comment all his moves for landing, as he did for takeoff. Again: watch carefully!   

The briefing part of this lesson referred to a number of PILOT NOTES. This will happen again repetitively. At this stage, these notes do not require a very deep study (although very soon they will), as much of their contents is premature anyway. None the less, a first reading of the matters discussed so far is highly recommendable.   

Note: Many airports require the use of radiophony, which unfortunately is an additional difficulty for the student. Even at smaller airfields where radio is not a requirement,  it must be kept in mind that the need to obtain the radiophony endorsement remains for later navigation flights. It is thus of utmost importance to follow the related groundcourse and associated training as soon as possible (see also PILOT NOTE V)   

 
C. - QUESTIONARY (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)
   
01. - (POH) Your training aircraft is: a) an all metal structure, b) an all wood structure, c) an all composite structure d) neither a, b or c.   

02. - State the difference between a monocoque and a semi-monocoque structure.   

03. - What do you understand by stressed skin?   

04. - (POH) The engine of your training aircraft has _________ cylinders: a) in line, b) radial, c) horizontally opposed   

05. - What is the purpose of the firewall? Where is it located?
   
06. - The wing section is determined by: a) the spars, b) the ribs
   
07. - (POH) The wings of your training aircraft are: a) a cantilever monoplane design, b) a semi-cantilever monoplane design c) a biplane design.   

08. - What do you understand by a tapered wing? The taper, if any, affects both the ________ and the _________ of the wing   

09. - Tapered wings are mainly a characteristic of: a) cantilever designs, b) semi-cantilever designs, c) biplane designs.   

10. - What do you understand by dihedral? What is its main purpose?   

11. - State the general purpose of the horizontal and vertical tailfins.
   
12. - What do you understand by flight control flutter? What is its basic cause? How is it eliminated?   

13. - (POH) The shock absorbing system of the landing gear on your training aircraft is: a) oleo-pneumatic, b) leaf spring,    c) elastic, d) other.   

14. - The cabin windows are made of _________. Cleaning them with gasoline is: a) the most efficient way, b) likely to cause damage.   

15. - You push the stick forward: the __________ moves ___________   

16. - You move the stick to the left: the left __________ moves ___________, the right ___________ moves ___________

17. - You push in the right rudder pedal: the __________ moves to the __________   

 
18. - (POH) Your training aircraft is fitted with: a) electrically actuated flaps, b) hydraulically actuated flaps, c) pneumatically actuated flaps, d) manually actuated flaps, e) no flaps.   

19. - In case of fire in the cabin during flight, the fire extinguisher can be used without any problem. True or false?   

20. - The flight instruments related to the pitot tube are: a) the altimeter, b) the vertical speed indicator, c) the airspeed indicator, d) a, band c.   

21. - The flight instruments related to the static air system are: a) the altimeter, b) the vertical speed indicator, c) the airspeed indicator, d) a, b and c   

22. - By blowing into the pitot tube, you are likely to destroy the ____________   

23. - Calculate the following:
   
- 1500 feet =              _____________  meters   
- 120 knots =              _____________  km/h   
- 12 nautical miles =          _____________  km   
- 12 statute miles =            _____________  km   
- 135 miles per hour =      _____________  km/h   
- 300 km/h =              _____________  knots   
- 300 km/h =             _____________  mph   

24. - State the purpose of the pitot cover.   

25. - Static air pressure inlets are located either side of the pitot tube or of the fuselage. Why?   

26. - State three gyroscopic instruments.   

27. - Gyroscopic instruments can be operated electrically or by a ____________ driven by the engine. An outdated way consists of a ___________ usually mounted on the underside of the fuselage.   

28. - (POH) Considering the fuel system of your training aircraft state:
   
- the number of fuel tanks ____
- their usable contents in USG _____, in liter _____, in Imp. gall. _____   
- the various usable types of gasoline with their associated colour.   

29. - When is it necessary to check the fuel system for possible water or contaminants?   

30. - (POH) State the location of the various fuel draining valves on your training aircraft. How can you actually see that water is present in the fuel?   

31. - During the preflight external inspection, you should verify the fuel contents on the gauges. True or false?   

32. - (POH) State the location of the various fuel tank vents on your training aircraft.   

33. - (POH) Considering the engine oH system of your training aircraft, state:   

- the maximum capacity ______ USG   
- the minimum safe value _____ USG   

34. - The air which is directed towards the carburettor is always filtered. True or false?   

35. - On your training aircraft, the carburettor air intake is located: a) below the engine cooling air intakes, b) within the engine cooling air intakes   

36. - State all the documents which, by law, must be on board of the aircraft.   

37. - State the purpose of the carburettor.   

38. - During flight, despite the fact that the position of the throttle lever has been unchanged, you notice a gradual drop of RPM. What is the most probable cause? What can you do about it?   
   
39. - The ignition system is composed of two independent __________  whose purpose it is to ignite the _________ mixture within the __________

40. - You wish to swing the propeller around by hand. State the required precautions.   

41. - Electricity is obtained from the __________ which is kept properly charged by the _________ driven by the _________

42. - Each electrical appliance is protected from a short-circuit and possible resulting fire by a ___________

 

A.    - BRIEFING (01,00 h. - Total 04,00 h.)
   
Before studying the primary effects of the control surfaces, let us first discuss a few basic principles of flight.

The four forces acting on an aircraft in level flight (fig. 1)

A force is anything which changes the state of rest or of motion of an object. In fact, a force produces either acceleration or a deceleration. Forces can be represented graphically in magnitude and direction by means of so-called vectors, i.e. oriented straight lines drawn to scale.

Forces can be generated in many ways. One particular example is due to the Earth's attraction, or gravity, which exerts itself on anyone and anything, and gives way to the tendency of any mass to accelerate straight towards the center of the planet or, to put it simply: to fall. This acceleration due to gravity results in the force known as weight (gewicht/poids).

Aircraft are of course also submitted to gravity and should normally fallout of the sky, were it does not due to a force acting against this inopportune tendency. This force is the lift (draagkracht/portance), which is produced by the wings and acts in opposite direction to the weight. In aerodynamics, the lift is represented by the symbol Fz.   

However, wings are unable to produce lift by sheer magic: a certain amount of forward velocity is necessary so that the airflow over the wing can give way to the required lift. This forward velocity is the result of the engine's thrust (trekkracht/tractian).   

Now, anything which moves in the Earth's atmosphere suffers a certain amount of opposition from the air. This opposition is known as drag (weerstand/traînée), and is represented in aerodynamics by the symbol Fx. Drag opposes the thrust and, as such it is a prejudicial force because it hinders the development of forward velocity.   

Note that when the lift equals the weight, the aircraft will neither descend, nor climb: it will maintain a constant altitude. On the other hand, when the thrust equals the drag, the aircraft will not remain motionless, as certain individuals tend to believe, but it will move at a uniform velocity in the direction of the thrust. However, assuming that the thrust becomes greater than the drag, the aircraft will accelerate: the drag, which is a direct result from the airspeed, will increase- as well, until it equals the new thrust value, at which moment the velocity will again remain uniform, albeit at a higher value. Conversely, if the thrust is reduced below the current drag value, the velocity will decrease, the drag will decrease as well, and once both forces are again exactly opposite to each other, the velocity will again be uniform, but at a lesser value.   

The drag being a prejudicial but inevitable force, aircraft as well as car manufacturers try to keep it as small as possible. Indeed, the smaller the drag, the smaller will be the required thrust, thus the fuel consumption, to reach and maintain a given speed and, as far as aircraft are concerned, to obtain the required lift. In other words, aircraft are designed in such a way that a maximum of lift is obtained for a minimum of drag. With this principle in mind, fig. lb, where all four forces are represented with the same magnitude is completely erroneous. In fact, the value of the lift is at least eight times greater than the value of the drag. Fig. l is thus a more accurate representation of the four forces acting on an aircraft in level flight.   

Note already now that the value of both the lift Fz and the drag Fx depends on a number of factors, namely:   

1°) the air density: it is obvious that "thinner" air will produce less drag, but will also tend to develop less lift; the air density's symbol is 1/2 e (greek letter "rho");   

2°) the surface S of the wing: a greater surface develops more lift , but also more drag;   

3°) the velocity V: it has been experimentally determined that both lift and drag increase with the square of the velocity, i.e. if the velocity is doubled, Fz and Fx are four times greater;   

4°) the shape of the wing, i.e. the wing's profile (see below) and planform;   

5°) the wing's angle of attack which will be discussed hereafter, plays a major part.   

Both the shape of the wing and its angle of attack, as well as the wing's cleanliness, determine the so-called lift and drag coefficients, respectively Cz and Cx which, in turn, influence the global value of Fz and Fx.

These factors are summed up into the two basic formulas of flight, formulas which you will constantly meet in one form or another when you will be studying aerodynamics for more advanced pilot licences:   

- Fz = 1/2 e  S  V²  Cz   

- Fx = 1/2 e  S  V²  Cx   

 
To complete this first acquaintance with weight, lift, thrust and drag, keep the following tip in mind as it might be useful later: whenever an aircraft moves at a uniform velocity, the forces acting on it are in equilibrium. Consequently, if these forces are connected to each other, one must obtain a perfectly closed figure. For instance, if we consider level flight, the forces represented in fig. l can as well be represented as in fig.2 which indeed is a closed figure, in this specific case a rectangle because the aircraft is considered in level flight. This would be impossible if the forces were not in equilibrium, such as during a deceleration whereby the thrust is smaller than the drag (fig  2 bis).   

Chord and angle of attack (fig. 3)   

The forward edge of the wing is known as leading edge (aanvalsboord/bord d'attaque), the rear edge being known as trailing edge (vluchtboord/bord de fuite). Figure 3 represents a wing section, or wing profile, (vleugelprofiel/profil d'aile), i.e. the shape of the wing which we discussed a moment ago, and which may vary significantly from one aircraft type to another (this will be further discussed in lesson 07). The imaginary line between the leading edge and the trailing edge is called the chord (koorde/corde) of the wing.   

The angle of attack (aanvalshoek/angle d'attaque) is the angle between the chord of the wing and the airflow, or relative wind (relatieve wind/vent relatif), generated opposite to the direction of motion. The angle of attack is often represented by the greek letter alpha λ. It is variable and can be changed by the pilot, as will be explained later.
   
The definition on the angle of attack is extremely important because it will often be brought to attention during the following lessons. Most pilots associate the term "angle of attack" solely with the wing as such, which in itself is perfectly correct. Still, the definition will also prove useful to analyse the operation of the flight controls. A lot is to be said about the angle of attack but, at this stage, suffice it to know that when the angle of attack increases both lift and drag will increase, and vice-versa.   

The three axes of the aircraft (fig.4)   

As it is the case for the chord of the wing, the three axes of the aircraft are imaginary lines. They can be compared to hinges around which the aircraft can rotate. These are:
   
a) the longitudinal axis, or roll axis (langsas of rolas/axe longitudinal ou axe de roulis) extending from the nosetip to the tailtip;

b) the lateral axis, or pitch axis (dwarsas of stampas/axe lateral ou axe de tangage) extending from one wingtip to the other;   

c) the vertical axis, or yaw axis (verticale as of tapas/axe vertical ou axe de lacet), at right angles to the two other axes.   

The three axes intersect at the center of gravity, and the aircraft can thus:   
   
a) roll or bank, around its roll axis, either to the left or to the right (rollen of hellen/s'incliner);

b) pitch around the pitch axis, either upward or downward (stampen/tanguer);  

c) yaw around the yaw axis, either to the left or to the right (gieren/cadence).   

Although these three motions, roll, pitch and yaw, can be the result of external factors such as turbulence, they are normally generated by the pilot himself, by means of the control surfaces (raeren/gouvernes), when using the flight controls (stuurorganen/organes de contrôle), i.e. the stick or the rudder pedals.   

The control surfaces and their primary effects

We could as well say "the primary effects of the flight controls”, the term "flight controls" being often used to designate either the stick and rudder pedals, or the control surfaces themselves. Although it may seem a little pedantic, there is in fact a difference between "control surfaces" and "flight controls", the latter being the means to move the control surfaces.
   
As the aircraft is able to move around three "hinges", there are three different control surface systems, the ailerons, the rudder and the elevator, which are operated through three associated flight control systems, i.e. the stick (used for two different control surface systems) and the rudder pedals.   

a) The ailerons are operated by moving the stick to the left or to the right. Assuming that the stick is moved to the left, the right aileron moves down while the left aileron moves up. The fact that this causes the aircraft to bank to the left is normally considered as plain common sense. There is however a more "scientific" explanation to this roll motion, and this is where we must fall back on the definition of the angle of attack, and what happens when it increases or decreases. Indeed, the downgoing right aileron causes that part of the wing trailing edge to be lowered and, because the leading edge remains fixed in place, the wing's angle of attack at the level of the aileron increases thus giving way to a lift increase. On the other hand, the wing's angle of attack at the level of the upgoing left aileron decreases, and becomes even negative so that here, the lift does not only decrease, but acts even downward. This combination causes inevitably a roll motion to the left. This roll motion, either to the left or to the right, is the primary effect of the ailerons.   

 
b) The elevator is also operated by moving the stick, but this time either forward or rearward. If we push the stick forward, the elevator moves down, the angle of attack of the horizontal tailplane increases, and so does its lift. Consequently, the nose pitches down. If we pull the stick rearward, the elevator moves up, the angle of attack of the horizontal tailplane becomes negative so that its lift acts now downward and causes the nose to pitch up. This up or down pitch motion is the primary effect of the elevator.   

Note: On some aircraft, the horizontal tailplane and the elevator form one single unit moving upward or downward. This is the case for instance on the Piper "Warrior II" PA-28-161. Such a design is known as flying tail, or stabilator (contraction of "stabilizer" - which is the same as horizontal tailplane - and "elevator"). Besides the fact that it is somewhat more sensitive, the stabilator operates according to the same principle as the usual elevator.   

c) The rudder is operated by moving the rudder pedals either to the left or to the right. If the left rudder pedal is depressed, the rudder moves to the left. Once again, this causes an increase of the angle of attack and the resulting aerodynamic reaction (in this case one can hardly use the term "lift") exerts itself to the right. As a consequence, the nose yaws to the left. Conversely, if the right rudder pedal is depressed, the nose will yaw to the right. This left or right yaw motion is the primary effect of the rudder.   


B.- FLIGHT TRAINING (Dual 00,45 h. - Total 01,30 h.)

   
You should now be able to perform the complete preflight inspection, including the external inspection and the various checklists before takeoff. Of course, all this will happen under close supervision of your instructor who might very well take this opportunity to test you somewhat about the material you learned till now.

Unless the parking area is crowded, he will probably let you taxi the aircraft, i.e. steer it on the ground from the parking area to the runway holding point where the engine run-up is to be carried out. All you have to do is to follow his instructions: full explanations about the taxi procedure will be given at a later stage.   

You will perform the engine run-up: the instructor will help you by telling you what to do and what to verify (c/f PILOT NOTE I: "BASIC PRINCIPLES OF LIGHT AIRCRAFT ENGINES").

The instructor will fly the aircraft but this time, in order to get more acquainted with the "feel", you must "follow on the controls", i.e. keep one hand lightly on the stick (the other on your lap or, if the cockpit is a "tandem" design, on the throttle lever): at any rate, avoid to hold the stick with both hands.   

During climb, he might ask you to maintain the climb attitude with the wings level by using mainly external references. Perhaps you will already notice the need for some rudder input during climb: this will be clarified later.   

Upon approaching the cruising altitude, the instructor will tell you to push the stick gently forward in order to lower the nose and bring it in the attitude which you believe is the correct one to maintain level flight. You will then reduce the RPM to cruise value and try to maintain level flight for a while. Don't worry; your instructor will nurse you as a mother hen! You will perhaps feel the need to keep pushing on that stick to maintain the altimeter reading unchanged: this is normal and due to the trim surface which is still adjusted for climb, not for level flight. The instructor will take over; show you the trim re-adjustment and subsequent "hands off" flight, i.e. the aircraft flying now all by itself. The trim will be further discussed at a later stage as well.   

Leave the controls alone, relax and watch: the instructor will now demonstrate and comment the primary effects to you:
   
1°) He will do this by moving the stick alternatively to the left and to the right, using only small and short inputs (to avoid as much as possible the appearance of the secondary effects which will be discussed during the following lesson): simply observe the resulting roll motions to the left and to the    right.   

2°) Next, he alternatively will move the stick gently aft and fore: observe the resulting nose pitching up and down. Note that each time the nose pitches down, you might have the rather queer sensation to come loose from your seat: nothing wrong with it, it is absolutely normal (this is known as a mild "negative G effect"; "G's" will be discussed later).
   
3°) Finally he will alternatively move the rudder pedals to the left and to the right, again using small inputs to avoid the secondary effects: observe the nose yawing to the left and to the right.   

You will now be requested to take over again and produce the primary effects yourself by following the instructor's orders: "bank left..., wings level..., bank right..., wings level... ", "pitch up...., pitch normal..., pitch down..., pitch normal... ", "yaw left..., yaw zero..., yaw right..., yaw zero "...
   
After this little exercise, you will be requested to maintain the aircraft in level flight to the best of your abilities, and to return to the airport. As a direction change will probably be necessary, simply and very slightly bank the aircraft in the required direction: you will notice that the aircraft starts turning. When in the right direction, simply bring the wings to level attitude again: the turn will stop.   

 
The instructor will take over to execute and comment the approach and landing, but this time with you still following at the controls.   

After landing, you will be requested to taxi towards the apron where the instructor might take over to park the aircraft correctly. You will then shut the engine down and perform the "SECURING" checklist.   
   

C.    - QUESTIONARY    (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)
   
01.    - State and represent graphically the four forces acting on an aircraft in level flight at uniform airspeed.   

02.    - The origin of the weight is the ________________________

03.    - Fz represents ________________; Fx represents __________________

04.    - The drag is caused by _____________

05.    - Assuming that the velocity increases 3 times, the lift and drag will increase _____ times.   

06.    - State the basic formulas of Fz and Fx.   

07.    - State three (3) factors which influence the ez and ex coefficients.   

08.    - The forward edge of the wing is known as __________ edge; the rear edge of the wing is known as __________ edge.   

09.    - What do you understand by the chord of the wing?   

10.    - What do you understand by angle of attack ?   

11.    - What happens to lift and drag when the angle of attack:   

a) increases: ____________
b) decreases: ____________

12.    - State the three axes of the aircraft, their associated control surfaces and their associated flight controls.   

13.    - What do you understand by a stabilator?

14.     - Explain why a downgoing aileron causes the associated wing to move upward.   

15.    - Explain why en upgoing aileron causes the associated wing to move downward.   

16.    - State the primary effects of:
   
a) the ailerons ____________________________________________________
b) the elevator ____________________________________________________
c) the rudder _____________________________________________________

17. - (POH) You check the magnetos before takeoff:   

a) at which RPM ?   
b) maximum RPM drop is   
c) maximum differential is

A.- BRIEFING (01,00 h. - Total 05,00 h.)   

a)    Secondary effects of the ailerons (fig. 1)   

When we cause the aircraft to bank around its roll axis by moving the stick to the left or to the right, the lift vector Fz which is always oriented at right angles to the airflow over the wing will obviously tilt as well. In other words, when the aircraft is banked, the weight (G) and the lift (Fz) are no longer exactly opposite to each other, an angle is formed between these two forces and a resulting force (R) is generated. This resulting force acts towards the low wing and causes the aircraft to slip (slippen/glisser) accordingly. This slipping motion generates lateral relative wind acting on the fuselage and on the vertical fin: as the major part of the fuselage, and particularly the vertical fin, is located behind the center of gravity, the aircraft tends to rotate around the yaw axis towards the low wing. This yaw motion is known as weathervane effect (windhaaneffect/effet de girouette) and is the secondary effect of the ailerons.   

Note that force R also acts onto the occupants which will experience the feeling of gliding sideways towards the low wing, as well as on the so-called ball (kogel/bille), i. e. an agate (agaat/agate) ball moving in a curved alcohol filled glass tube (usually as part of the turn indicator), and which also moves towards the low wing.   

In fact, the weathervane effect is not the sole secondary effect of the ailerons: there is another one which occurs at the very moment that the ailerons are deflected. Indeed, we know that the downgoing aileron produces more lift, but this inevitably also produces more drag: this means that if we move the stick, for instance to the left in order to bank to the left, the drag increase on the right aileron (the one which is going down) produces   
a retarding effect and causes the aircraft to yaw . . . . . to the right, known as the aileron drag (rolroerweerstand/traînée d'aileron), and the resulting yaw is the so-called adverse yaw (????/lacet inverse). However, the adverse yaw is usually rather difficult to detect, particularly for beginners, firstly because the manufacturer tries to eliminate it as much as possible by means of various construction tricks (these will be discussed during the groundcourse), secondly because it is rapidly substituted by the weathervane effect: during the demonstration in flight, very close observation of the aircraft's nose will probably be required to notice it. Nonetheless, aileron drag is a fact and, as we shall see later, it proves useful under certain circumstances.   

During the demonstration of the secondary effects of the ailerons, you will notice that the flight direction changes considerably. This is partly due to the yaw motion which is allowed to develop (and which also causes the nose to go down) but, as we shall see when studying the turns, it is also due to the fact that the lift vector is tilted. At any rate, keep in mind that banking the aircraft, even slightly, always causes a direction change toward the low wing.   

b) Secondary effect of the rudder (fig. 2)   

When we cause the aircraft to rotate around its yaw axis by means of the rudder, say for instance to the left, the right wing develops a higher angular velocity than the left one. Compare this to a row of soldiers aligned beside each other and executing a turn: the innermost one remains practically on the spot whereas the outermost one is nearly running to stay in line. As a higher velocity generates more lift, the right wing tends to move up, i.e. the aircraft banks to the left. In other words, an initial motion around the yaw axis generates a resulting motion around the roll axis, known as induced roll (geïnduceerde roI/roulis induit) which is the secondary effect of the rudder.   

As the initial motion around the yaw axis causes the nose to move sideways, to the left in this example, a direction change to the left will obviously occur but, due to its inertia, the aircraft tends to maintain a rectilinear trajectory and skids (schuiven/déraper) towards the outside of the curve, in this example to the right. This tendency is clearly felt by the occupants, and also acts onto the ball which will deflect to the right.   

Before discussing the elevator, the previous allows the following conclusion with regard to the ball: it reacts to lateral forces acting onto the aircraft which, at least as far as level flight is concerned, should be non-existent. In other words, the ball should remain centered. Keep in mind the following: moving the stick to one side attracts the ball, moving the rudder to one side repels it.   

c) Secondary effects of the elevator
   
The elevator is said to have no secondary effects, although its use implies certain consequences:
   
a) When the aircraft is caused to pitch up by means of the elevator, the altitude will increase and the airspeed will decrease;   

b) When the aircraft is caused to pitch down by means of the elevator, the altitude will decrease and the airspeed will increase.   

Although these consequences are rather evident and perfectly understandable, why are they not considered as secondary effects? Because a control surface effect, whether a primary or a secondary one, is by definition a certain motion around a certain axis. As the use of the elevator implies solely a motion around the pitch axis, one talk about consequences instead of secondary effects. In fact, this is simply a matter of conventions. An additional aspect regarding the use of the elevator concerns the engine1s RPM, at least as far as a so-called fixed pitch propeller is used, which is mostly the case on elementary trainers: because of the forces acting on the propeller, the RPM tends to decrease when the airspeed decreases and vice-versa. More about the propeller at a later stage.   
Let us now rapidly wrap up the primary and secondary effects of the control surfaces:   


CONTROL SURFACE        PRIMARY EFFECT         SECONDARY EFFECT

AILERONS                            BANK L/R                    YAW L/R

RUDDER                               YAW L/R                    BANK L/R

ELEVATOR                       PITCH UP/DOWN        NIL, BUT AIRSPEED &
                                                                     ALTITUDE CHANGES



You can now practice straight and level flight with some more knowledge in the back of your mind. Straight and level means flying at a constant altitude, at a constant airspeed, presently the normal cruising speed, and in a constant direction. In order to achieve the cruising speed, a certain engine power output or RPM must be selected, say for instance 2300 RPM for an indicated airspeed (lAS) of 95 kts. Note that a choice of power settings and associated speeds can be found in the POR but, for training purposes, the instructor will provide you with this information. At any rate, taking into consideration what has been observed during the demonstration of the primary and secondary effects or consequences:   

1°) Ensure that the correct power setting (RPM) is set;   

2°) Keep the rudder pedals neutral. Although this might seem evident, it is not always the case: indeed, as we shall see later, at airspeeds significantly different from the normal cruise value, some rudder pedal input may be required because of certain propeller effects. But this will be taken care of later: when at normal cruising speed, rudder pedals neutral! And remember to keep the tip of the feet on the lower edge of the rudder pedals: never let the full weight of your feet rest on them, as this is the best way to deflect the rudder inadvertently;   

3°) Keep the wings absolutely level: remember that even the slightest bank generates a direction change. Hold the stick lightly using one single hand; we may even say that two fingers are enough, to avoid inadvertent inputs. Relax!   

4°) Keep the nose of the aircraft in the correct attitude in relation to the horizon or, if it is not clearly distinct, to the ground. Remember what happens to altitude and airspeed if the nose is too high or too low. Avoiding unwanted pitch inputs in another reason to hold the stick lightly. Think also about the possible resulting RPM variations which are often clearly audible even before they are noticed on the indicator: there is sometimes a tendency to re-adjust the throttle lever, whereas the RPM variation is due to an incorrect nose attitude. Also ensure that the throttle friction lock is sufficiently tightened to avoid the lever creeping away from its selected position because of the engine vibrations.   

5°) Keep in mind that the ball should be centered at all times. If this is not the case, it means that a lateral force exerts itself on the aircraft, possibly because the wings are slightly banked, but most usually because you inadvertently depress the rudder pedals: this latter case is the most common and is due to the PILOT being too tense. Once again: RELAX!!! This is the key word for proper flying technique.

   
B.    - FLIGHT TRAINING (Dual 00, 45 h. - Total 02,15 h.)   


Once again you will perform all inspections and checks as for the previous session. This time you should be able to correctly and completely perform the engine run-up without the assistance of the instructor.   

You will now perform the takeoff and initial climb yourself, albeit closely nursed by the instructor: for the previous lesson, he was flying and you were following at the controls; now you will be flying and he will follow at the controls and assist you as needed until the aircraft is levelled off at the cruising altitude.   

The instructor will now take over. Leave now the controls alone, relax completely, and be ready to observe closely all motions of the aircraft. The instructor will first rapidly demonstrate the primary effects of the control surfaces once more.   

Next, he will proceed with the secondary effects, beginning with the ailerons first: try to notice the nose slightly yawing to the right when the stick is deflected to the left, and vice-versa. This is the adverse yaw, the result of the aileron drag. As said earlier, the adverse yaw is not always readily detectable: therefore the demonstration will begin with a few rapid and repetitive left/right motions of the stick, avoiding the appearance of the weathervane effect, until you clearly noticed the phenomenon.
   
He will then allow the weathervane effect to develop: watch the ball deflecting definitely to the low wing, the nose yawing accordingly, and the subsequent direction change. Note that the yawing motion inevitably results in a nose down attitude and a consequent increase of airspeed and altitude loss. This demonstration, which is carried out both sides, may be felt as rather uncomfortable for beginners, particularly because of the marked sensation of sliding away toward the low wing: however, there is absolutely no reason for concern. To put the aircraft back in level flight, suffice it to neutralize the ailerons and to pull back somewhat on the elevator.   

 
The next demonstration concerns the rudder and will also be carried out each side: watch the nose moving sideways, the ball moving in the opposite direction and the bank angle gradually increasing. Also here, the demonstration might end in a nose low attitude: to recover, the rudder pedals should simply be neutralized and back pressure applied on the elevator.   

Finally the elevator itself: the instructor will gently pull up in a more or less steep attitude: notice the altitude increasing and the airspeed gradually decaying, no significant motion around another axis occurs (except that you might perhaps detect some amount of yaw and the ball moving away from center: this is not a secondary effect of the elevator, but a result of the propeller effects which will be discussed later) . Note also the RPM gradually decreasing. The instructor will then put the aircraft into a gentle dive: the airspeed increases, the altitude decreases and the engine RPM goes up.   

After completion of these demonstrations, you will take over again and repeat them for yourself. Although flight control inputs are usually extremely small, this is an occasion where you are allowed to handle them somewhat more firmly in order to clearly obtain the result you seek: don't worry, nothing can happen, and it is a good way to build up confidence.   

As before, the instructor will ask you to determine the airport's direction, then to proceed towards it in straight and level flight. To this purpose, remember: correct power setting, hold the controls lightly, keep the nose in the correct attitude using mainly external references (but crosscheck once in a while with the altimeter: if you are slightly high gently push the nose down, if you are slightly low, gently pull it up, at this time disregarding possible speed variations). As for the direction, keep the wings level, or bring them back to level if disturbed by some turbulence, pick up a landmark as far away as possible in front of you, fly straight towards it... and stay relaxed! This time the instructor will nurse you through the approach and landing, i.e. you will actually be flying the aircraft throughout but, of course, very closely monitored and assisted.   


C.    - QUESTIONARY    (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)  

01. - You bank the aircraft to the left, what happens with the lift vector?   

02. - When the aircraft is banked, it begins to slip to the low wing. Why?   

03. - What do you understand by weathervane effect?

04. - Describe the secondary effects of the ailerons and the various involved causes.   

05. - What do you understand by adverse yaw?   

06. - Describe the secondary effects of the rudder and their cause.   

07. - What do you understand by induced roll?   
   
08. - You deflect the stick to the left, the ball tends to move to _________,you depress the rudder pedals to the left, the ball tends to move to    _________

09. - The elevator is said to have no secondary effects, only consequences. Why? Which are these consequences?  

10. - The material in which the ball is usually made is:    a) steel, b) aluminium, c) quartz.   

11. - What do you understand by angular speed of a wing?   

12. - IAS stands for    __________________

13. - What is the purpose of the throttle friction lock?

   
A. - BRIEFING (01,00 h. - Total 06,00 h.)   

I. - Taxi

The term "taxi", is related to aircraft moving on the ground under their own power.
   
On important airports, taxi, takeoff and landing are subjected to prior clearance by radio from the control tower. An ancient system, dating from the early days of aviation, consists of light signals given by the controller by means of a so-called Aldis lamp. Such signals can be given to aircraft in flight as well as on the ground, according to a specific code. Furthermore, flare signals (vuurpijlen/fusées) can be used as well.   

Although light and flare signals are no longer normally used these days at airports where radio transmissions are compulsory, under some circumstances they might still be, and particularly at smaller privately owned airfields (although, on many of these, no control whatsoever is provided and it is up to the pilot to act in accordance with the basic safety procedures which are discussed in the ground course about regulations). Furthermore, even at more important airports they might be helpful for aircraft having suffered a radio failure during flight. It is thus still necessary to know the significance of these various signals (see annex to this lesson).   

Incidentally, note that the use of the airborne radio is subject to an official authorization delivered by the Ministry of Communications, after the successful passing of an ad hoc examination. It is thus essential that you prepare yourself to pass it as soon as possible. In the meantime, see PILOT NOTE V, “THE VHF TRANSMITTER-RECEIVER": it includes amongst other things the required terminology for operations within the traffic circuit which you will probably need for your first solo flights.   

After the obtainment of the taxi clearance, ensure that the area around the aircraft is clear and that you will not hinder any incoming or outgoing traffic.   

It is fairly possible that the aircraft starts rolling as soon as the brakes are released: in this case there is no need to add power. On the other hand, if the aircraft is rather heavily loaded, some additional power may be required to get it moving. At any rate, once the aircraft starts rolling, and particularly when the parking brakes only have been released, the toe brakes should be tested. This should be done gently in view of the comfort of the passengers: note that it is simply a matter of verifying that the action on the brake pedals is satisfactory before taxiing any further, and there is no need to bring the aircraft again to an abrupt full stop. Consequently, and assuming that some additional power was required to get the aircraft moving, there is no need to throttle back. However, power must be reduced to idle (traagloop/ralenti) whenever a rapid full stop is required for some reason: in this case, the rule is never to brake against the engine power. Obviously, if the brake test proves unsatisfactory, the taxi should be interrupted immediately, and the engine shut down.

The taxi speed should always be extremely slow on crowded parking areas: watch the wing tips and, in case of any doubt with regard to a possible obstacle, stop the aircraft immediately; watch also the tail section if a short turn is required: don’t slam it against a hangar door or another aircraft. Important airports feature so-called taxilines, usually yellow colored, painted on the ground surface. Such lines are found on the parking areas, as well as on the taxiways where they act as centrelines. If such lines are available they should be followed as closely as possible because they (normally) ensure an obstacle free trajectory.   

Only once a free area is reached, such as on a taxiway, the taxi speed may be increased to a reasonable value, i.e. not too slow (taxi time costs money), but certainly not too fast: this is mainly a matter of common sense, keeping in mind that a too high rolling speed may very easily lead to loss of control, especially under high wind conditions, and particularly when a tail-wheel aircraft is involved.   

If one must pass over loose gravel during taxi, it is strongly recommended to reduce power to idle to avoid as much as possible suction of damaging rubble by the propeller. Also, when passing over a separation between concrete and soft ground or vice-versa, or any other sort of depression, the crossing should preferably be made obliquely, as slowly as possible, and with the stick full aft: if your aircraft is fitted with a nose-wheel, remember that the spacing between the propeller tips and the ground can be rather critical under such circumstances.   

It is sometimes recommended to keep the engine at about 1000 RPM during taxi. The reason behind this is to avoid carbon deposits on the spark-plugs (see PILOT NOTE I), as well as to improve the operation of the generator/alternator (see PILOT NOTE IV).   
Although these are two good reasons, it must not be forgotten that the taxi speed is likely to become excessive at such an RPM, particularly with tailwind and over concrete ground, thus calling for repetitive braking to keep the speed under control.This, in turn, might lead to break overheating and possible ensuing failure at the worst possible moment. Here again, it is a matter of common sense, keeping in mind that there is no major problem with maintaining the engine power to idle if circumstances do so dictate: assuming that carbon deposits have occurred on the spark-plugs, the problem will be detected during the engine run-up and can easily be cleared; as for the generator/alternator, even if it cuts off momentarily, electrical power remains supplied by the battery (see again pilot notes I and IV).   

 
As long as taxiing is carried out under no or light wind conditions, say less than 10 knots, the elevator and ailerons may be left unsolicited. Still, on aircraft with nose-wheel it is recommended to hold the stick forward to avoid the elevator slamming up and down when passing over rough ground. However, on aircraft with tail-wheel the stick should be kept full aft to avoid any possible tendency to nose over, and particularly in case of abrupt brake application. Directional control is obtained by use of the rudder pedals acting on the rudder surface: the airflow, even at low speed, is sufficient to cause the aircraft to turn either side. As far as nose-wheel aircraft are concerned, the rudder pedals, besides controlling the rudder, also (usually) act directly on the nose-wheel, which significantly simplifies the steering on ground. Note that, if a tight turn is required, the full rudder pedal input may be associated with braking to the same side (which is known as differential braking), as well as with a momentary power surge to increase the rudder efficiency. Nonetheless, such turns should be avoided whenever possible to prevent harmful twisting forces On the landing gear and tires.

Under stronger wind conditions, both the elevator and the ailerons become useful, even necessary. The following procedures are applicable:   

a) Elevator
   
On aircraft with nose-wheel, and assuming a headwind component (up to 90°), the elevator may be left down or, as usually preconized by Cessna, in neutral position: pulling on the stick to raise the elevator tends to lift the nose-wheel tire upward, thus decreasing its pressure on the ground surface and consequently decreasing its steering efficiency.   

On aircraft with tailwheel, the stick should be kept full aft so that the wind effect on the raised elevator ensures that the tail remains firmly on the ground.   

If on the other hand a tailwind component prevails, and that a tail-wheel aircraft is involved, full forward stick to keep the elevator down is essential: the wind acting on the upper side of the surface assists to prevent the aircraft from nosing over. As far as a nose-wheel is concerned, the procedure as recommended by Cessna is also to keep-the elevator down.
   
b) Ailerons   

Assuming crosswind, say from the right, two tendencies will show up:   

1°) a tendency for the right wing to move upward and the aircraft to roll to the left;

2°) weathervane effect (the same as in flight) whereby the aircraft has a tendency to yaw to the right.   
   
Obviously, these tendencies are more or less marked, depending on the wind velocity and the crosswind angle. Here we must distinguish between fore (up to 90°) and aft crosswind:   

- fore crosswind (up to 90°): keep the stick into the wind, i.e. to the right in this case. This counteracts the tendency to roll to the left. In addition, the drag produced by the left aileron, which is in down position (the previously discussed aileron drag), opposes the weathervane effect¡   

- aft crosswind: keep the stick to the left. The wind acts now on the upper surface of the right aileron, which is now in down position, and opposes both the roll tendency to the left (by pressing the aileron downward), and the weathervane effect (by pushing the down aileron forward) .   

To complete this general survey regarding taxi, note also the following:   

- On major airports, incoming aircraft are often met after landing by an official car from the airport authority, and led to the parking area. Such a car is clearly recognizable to its bright colours (usually mainly yellow), its rotating light, and the "FOLLOW MEH inscription. All you have to do is . . . .  to follow it, possibly notifying the ATC: "FOLLOW ME in sight".   

- The parking procedure itself is often directed by a so-called marshaller. You will find the various conventional signals which are used to this purpose, and which must be strictly followed, in annex to this lesson.   

- On any controlled airport or airfield, never enter an active runway without being positively authorized to do so!! And despite such authorization, always look out before entering or crossing it. Be aware that also air traffic controllers make mistakes once in a while: it would not be the first time that an aircraft is cleared to enter an active runway while another one is taking off or landing.   

- During taxi, ensure that the carburettor heating is not operating. Failing this precaution, unfiltered air is entering the system which, on ground, and particularly under dry and dusty conditions, is not precisely to be recommended (see PILOT NOTE I).
   
- A number of items must be verified during taxi. Although these may appear on the associated checklist, they must be known by heart, as taxiing and reading are not a good combination. At any rate, the taxi checklist should only be carried out when the aircraft is in an open area.   


 
II. - The engine run-up   

The engine run-up, i.e. the testing of the engine before takeoff, is to be carried out at the so-called holding point located on the taxiway, short of the takeoff runway, and usually indicated by a double yellow transverse line which, on controlled airports, may not be trespassed without clearance.   

The engine run-up must be carried out before each takeoff in accordance with the associated checklist, which should be known by heart as well. It includes the test of the ignition system (the magnetos), of the carburettor heating, the checking of some   
specific instruments and, depending on the aircraft type, possibly a few other items. Although the testing of the engine is covered in PILOT NOTE I, let us stress the following:   

- Assuming that the carburetor heating system proves inoperative, no takeoff should be attempted, whatever the weather conditions might be.   

- We know that, at least on aircraft fitted with a fixed pitch propeller, the RPM tends to increase with the airspeed. Consequently, assuming that for some reason a full power test should be dictated, the maximum attainable RPM will show ±200 RPM lower than the published maximum allowable value. This is absolutely normal, and is known as the static RPM, i.e. the maximum RPM which can be obtained when the aircraft is at a standstill: indeed, if the static RPM would already produce the maximum allowable value, it would rapidly be exceeded during the takeoff roll, which is always carried out at full power, and give way to severe damage, or even complete engine failure. This is also be discussed in PILOT NOTE II: "THE AIRCRAFT PROPELLER AND ITS EFFECTS"   

- It is recommended to perform the engine run-up with the aircraft facing the wind. The only reason behind this is to improve the engine cooling as long as the aircraft is motionless. As said, this is only a recommendation, not an obligation.   

- Be watchful that, at high power, the aircraft remains at standstill. Never blindly thrust the brakes: be prepared to reduce power instantly to idle if they should suddenly fail. Also be suspicious when very cold weather conditions prevail: local frosted spots on the ground surface may cause the aircraft to slide forward unnoticed. For these reasons, never perform the engine run-up too close from another aircraft.   


 
III. - Straight & level flight at normal cruising speed

You were already introduced to straight & level operation during the previous flight session. Let us now go through some further considerations:   

- In order to keep the flight direction unchanged, successive landmarks should be taken as far as possible in front, and the aircraft steered from one to the other. However, we must clarify the term "flight direction": because of possible crosswinds, the flight direction is not necessarily the direction in which the nose is pointed. We might even add that this is seldom the case! Indeed, assuming that the wind is coming from the left, the aircraft will drift off to the right and, if we take a landmark in front of the nose we will gradually, and mostly unconsciously¡ correct to the left so as to keep the landmark dead ahead. Of course we will ultimately reach it but we will in fact be flying a curved track instead of a straight one. This means that, in order to achieve a straight track, a drift correction must be applied against the wind thus in this case to the left: consequently¡ the chosen landmark should not be in front of the nose but somewhat to the right. This is the difference between the heading (the nose direction) and the route¡ or track, in relation to the ground (the flight direction) which is thoroughly discussed in. the navigation ground course. Besides the use of landmarks, and although the correct use of these instruments will be explained at a later stage, it is advisable to have a look once in a while to the magnetic compass or the directional gyro.   

- As said earlier, the flight direction tends to change if the wings are not perfectly level. Although a slightly banked attitude can easily be detected on the nose¡ it is also good practice to regularly compare the position of both wingtips in relation to the ground which¡ incidentally, is profitable for another extremely important matter, namely the look-out.   

- The following cannot be repeated and stressed enough: WATCH FOR THE PRESENCE OF OTHER AIRCRAFT!! AND ESPECIALLY IN THE CLOSE VICINITY OF AN AIRPORT!!! This is what is meant by the term "look-out". Monitoring the airspace around you is of vital importance! Too many fatal midair collisions occurred in the past! Look above you! below you! to the left! to the right! And yes, even behind you! Of course in the very beginning your look-out technique will be rather sloppy, as most of your attention will be drawn by actually flying the aircraft¡ but very soon you will be able to handle the machine almost instinctively while looking around. At any rate, you must attain a sufficient degree of proficiency in this regard prior to your first solo flight.   

- Another very important matter which must continuously be emphasized and which has already been raised previously, is the need to hold the stick as loosely as possible: unless strong turbulence prevails, two fingers are enough! Ensure that the tips of your feet rest lightly on the rudder pedals! Try to stay relaxed at all times! And incidentally unless no locking device keeping it in the required position is available, there is no need to hold your hand on the throttle lever during straight & level flight. Above all, and particularly assuming a control wheel instead of a stick, avoid to hold it with both hands! This is totally unnecessary certainly on light aircraft¡ and leads only to unconscious tension. Remember that the aircraft flies practically perfectly straight & level by itself, without any interference from the pilot, at least when the trim, which will be discussed in a moment, is correctly set.   

- Assuming that light, or even moderate turbulence prevails, there is no need to make very aggressive corrections to keep the wings level. Be aware that any aircraft is inherently stable and that, because of this, it tends to automatically resume level attitude when momentarily disturbed but this, of course, does not mean that you must do nothing at all.   

- As said earlier, the ball must be kept centred. It might oscillate somewhat but, if it persistently shows a deflection to the left or to the right, this usually is indicative of a too tense use of either rudder or ailerons: relax your grip and see what happens ! still, it may happen that the mounting of the ball's tube itself is not absolutely level, in which case a slight deflection is to be considered as normal.   

- Accustom yourself to check the indications of the so-called peripheral instruments (oil pressure, oil temperature, fuel gauges, ammeter, etc.) at more or less regular intervals, about every 10 to 15 minutes. This is to ensure that all systems are normal, and allows you to timely take adequate measures if needed. The handling of possible problems or anomalies will be discussed later.   

- Always strive to perfection! Of a pilot worth the name it is expected that he is able to maintain the required altitude, speed and heading respectively within plus or minus 100 feet, plus or minus 10 knots and plus or minus 10°. Note however that these are MAXIMUM momentarily allowable deviations which must be corrected back to the target value as soon as possible. In other words, as soon as you notice a deviation, even the slightest, do not delay the required corrective action.... but do it gently, without abruptness! In order to keep these three parameters as steady as possible, use mainly external references, i.e. landmarks, and the position of the nose and of the wing tips in relation to the ground. Nonetheless, also have a look once in a while to the various flight instruments: altimeter, airspeed indicator, variometer, magnetic compass and/or directional gyro (which will be further discussed later) and, why not, even the attitude indicator, often referred to as artificial horizon. However, the attention devoted to the flight instruments, as well as of the peripheral equipment for that matter, must be of very short duration: never keep staring at them! You are flying according to VFR, i.e. Visual Flying Rules, whereby, let us emphasize it once again, look-out remains essential.
   
- Finally, and this relates not only to straight & level flight at normal cruising speed but to any other situation, whether in horizontal attitude, during climb or during descent, remember that if the RPM (or, for aircraft fitted with a variable pitch propeller, the MAP) decreases without any obvious reason, THIS IS INDICATIVE OF CARBURETTOR ICING WHICH CAN VERY QUICKLY RESULT IN ENGINE STOPPAGE: the carburettor heating system must then be activated without any delay. Be aware that the density of the heated air is less, and that the fuel/air mixture will be temporarily too rich of fuel: as a consequence, engaging the carburettor heat will cause a further power decrease which is absolutely normal. The carburettor heating may be cancelled after a few seconds and the RPM (or MAP) will return to normal. It may happen that carburettor icing occurs repetitively under some weather conditions: in this case it is preferable to leave the heating system in operation, although this calls for an adjustment of the mixture control (see PILOT NOTE I).   


IV. - Trim tabs (fig. l)


Most elementary trainers are fitted with only one single movable trim surface, or trim tab, namely on the elevator. You have probably already been introduced to it during the very first lesson: it is located on the trailing edge of the elevator and can be adjusted from the cabin by means of a wheel or lever. Although it is very small compared to the control surface itself, effects of the elevator trim tab are considerable because of its distance from the aircraft's center of gravity.   

To clarify the operating principle of the elevator trim tab, let us consider an aircraft in level flight and assume that, for one reason or another, the center of gravity, is moved to the rear: one can easily imagine that this will cause the aircraft to pitch up. To counteract this tendency, the pilot must then exert a forward pressure on the stick and, assuming that he releases this pressure, the nose will immediately move upward again. In other words, the pilot is compelled to maintain this forward pressure to keep the aircraft in level flight. This becomes very tiring after a while, and inevitably results in decaying flying precision.   

Now, we know that when the stick is pushed forward, the elevator deflects downward. By properly adjusting the elevator trim upward, which corresponds to a "nose down" setting, the trim surface provides the necessary aerodynamic downward reaction, draws along the elevator to the required down position, and frees the pilot of any need to act further on the stick. Obviously, the reverse reasoning is valid if the C.G. would move forward and whereby a "nose up" adjustment would be required.   

The benefits provided by the elevator trim will become even more evident during climb or descent, as well as when flying level at speeds differing significantly from normal cruise value. During this flight session, the instructor will show you the effects of a poorly trimmed aircraft. However, keep in mind that the trim is not a flight control: the correct nose position must be maintained by means of the elevator, the trim being only used to eliminate any pressure that the pilot needs to exert on the stick so that the aircraft flies "hands off" and maintains the required pitch attitude by itself.   

 
The legendary and world-wide known Piper-Cub, a design dating from the thirties, has no trim tab whatsoever on the elevator. Here, it is the complete horizontal stabilizer (the horizontal tailplane) which is movable: in this case, it is its so-called angle of incidence (instelhoek/angle d'incidence), i. e. the angle between the chordline and the longitudinal axis of the aircraft, which can be varied to act as trim (fig. 2). The Piper-Cub is one of the very few light aircraft making use of this system. It is practically completely phased out on the more recent designs...... except on the present day heavy jets where the principle of the "movable stabilizer" is almost universally applied because of its great efficiency.   

More advanced aircraft are fitted with rudder and/or aileron trims as well. This allows to eliminate any unwanted tendency to yaw or to roll, tendencies which are usually the result of some minor structural inaccuracies. Some models, such as the Piper "Warrior", feature an internal rudder trim system, i. e. an adjustable spring connected to the rudder cable, and whereby no external trim surface is present.   

Besides movable trim tabs, there are also fixed trimming surfaces, often referred to as flettners (although this latter denomination might be argued), which cannot be adjusted from the cabin. These are in fact a cheap replacement of the movable system. They are mostly to be found on the ailerons and/or on the rudder of elementary trainers, although more advanced aircraft types may be fitted with them as well. Fixed trimming surfaces are small aluminium plates which are bent up or down to obtain the required result. As we mentioned it before, any aircraft may suffer minor structural inaccuracies causing it to roll or to yaw. Such tendencies can be taken care of by these plates, but this solution implies a few drawbacks: firstly, in order to obtain the correct adjustment, one, and often more testflights are necessary secondly, the system can easily be put out of order if something or someone hits the plates when the aircraft is on ground, and thirdly, a correct adjustment is only valid for one single airspeed, usually the normal cruising speed.

   
V. - Balance and anti-balance tabs
   
Although they look just like the usual movable trim tabs and can be used on any control surface, the operating principle of balance tabs is different. Let us examine for instance an elevator balance tab: in we push the stick forward to move the elevator down, the balance tab is caused to move in opposite sense, i. e. upward. This provides a downward aerodynamic reaction which assists the downward motion of the elevator (fig. 3). Conversely, if we pull on the stick, the balance tab moves down and assists the upward motion of the elevator. In fact, the purpose of a balance tab is to use its aerodynamic reactions to decrease the force required from the pilot to move the associated flight control.
   
 
Whereas balance tabs move opposite to the associated control surface, anti-balance tabs move in the same sense, as shown in fig. 4. The idea behind this design is to increase the curvature of the control surface, thus increasing its overall efficiency.
   
Note that both balance and anti-balance tab systems can be independent from the trimming surfaces, but may combine the function of movable trim surface as well. This is for instance the case on the Piper "Warrior" where the elevator (in casu a stabilator) is fitted with an anti-balance tab which also operates as trimming surface.   

   
B. - FLIGHT TRAINING (Dual 00,45 h. - Total 03,00 h.)

   
From now on it will always be your job to perform the various inspections of the aircraft, the various checklists, the taxi, the engine run-up, in other words, everything which must be done before takeoff (except, at this stage, taxiing the aircraft on your own to the fuelling station: wait for this until your instructor clears you to do so).
   
As far as the external inspection is concerned, remember that the aircraft must not only be in good technical condition, it must also be clean: use a rag and wipe off any possible traces of oil,or other liquids! If necessary wipe off mud as well!!! And don't forget to check that the windshield is clean!

If radiophony is necessary, you will do the talking to obtain the taxi and takeoff clearances (see PILOT NOTE V: "THE VHF TRANSMITTER-RECEIVER) this will help you to overcome “mike-fear", a problem with many beginners. Accustom yourself to carry a kneeboard on which to note the runway in use, the wind direction and velocity, and the QNE (the QNH will be fully discussed during the groundcourse of meteorology: it is expressed in millibars, in three or four ciphers: 1015, 980, 1030, or whichever value. If your first attempts turn out to be a little clumsy and time consuming, don't worry, it will rapidly improve.   

So far, you had twice the opportunity to "follow" a takeoff and a landing, you probably handled the aircraft already for both climb and descent. Despite the fact that none of these subjects has been covered yet, you will perform all the flying yourself, including the takeoff and landing, following to the best of your abilities the advices of your instructor who, of course, will "nurse" you very closely. Here again, don't worry if you encounter some difficulties and that the instructor must intervene more often than not (the contrary would be rather surprising): it is simply a matter of "getting the feeling" of things which will all be explained and fully understood in a very near future.
   
 
Once at cruising altitude, the core of this session will be the practice of straight & level flight at normal cruising speed. Keep in mind the various advices laid down in the briefing. Call out the various readings of the peripheral instruments each time you check them, for example: "OH pressure OK, oil temperature OK, fuel gauge OK, ammeter OK, etc." But do actually check them! not merely call them out without looking! For instance, if the fuel gauge nears zero, say so! It might be time to return to the base!!   

In order to emphasize the necessity for correct trimming, the instructor will take over the controls and tell you to relax. He will then significantly detrim the aircraft one way or the other while keeping the correct pitch attitude, then hand over the controls back to you with the request to maintain level flight for a few moments: you will immediately notice the difficulty to fly accurately. After a while he will tell you to re-adjust the trim until no more marked tendency to pitch up or down occurs.   

As far as trimming is concerned, any time you feel that you must exert a considerable force on the stick to maintain (or to take) the correct pitch attitude, don't hesitate to use large and rapid trim inputs to eliminate the gross of the force required; once this is done, fine tune the trim setting until the pitch attitude remains unchanged without any further elevator input. Be also aware of the fact that a trim setting can be suitable at one moment, but unsuitable at another, as indeed the position of the center of gravity may vary slightly during flight due to the gradual decrease of fuel contents. This is why it is necessary to hold the stick lightly, to be able to detect the slightest change in trim requirement. This is also why the instructor will often suggest you to release the stick altogether for a moment: if you notice that the nose tends to pitch up or down, even slightly, re-adjust with the elevator, THENCE re-adjust the trim.   

Think about the look-out: this is not only a matter of good procedural behaviour, IT IS OF VITAL IMPORTANCE! Accustom yourself to look to the rear once in a while..., without pulling or pushing inadvertently on the stick another reason why a light touch on the controls is necessary.   

All these proceedings may seem rather complicated in the beginning. They are not, they simply require some exercise and routine and, although the first endeavours might be somewhat discouraging, they will soon become kind of a second nature.

Flying straight & level for some time may lead the aircraft far away from base. Therefore some turns will be necessary. Turns will be discussed with the next lesson. At present, if the instructor requests you to turn to the left or to the right, simply bank the aircraft slightly in the required sense: the direction will change automatically. To stop the turn and resume straight and level flight, put the wings gently level again.   

Assuming that your training aircraft is fitted with the three gyroscopic instruments mentioned earlier, the instructor will spend a few minutes to draw your attention on the following:   

a) Attitude indicator: when flying straight & level at normal cruising speed the model aircraft is almost exactly aligned on top of the horizon bar. If the model aircraft deviates upward from this position, the nose is too high, the airspeed decreases, the variometer shows an up trend and the altitude increases (and the engine RPM is likely to decrease) . The reverse happens of course if the model aircraft is too low. On the other hand, as long as the model aircraft remains parallel to the horizon bar and that the ball is centered, the heading remains unchanged and the turn indicator shows no deflection either left or right. He will also draw your attention to the bank graduations, usually on the upper edge of the instrument, and the associated bank pointer: the bank scale always include 10°, 20° and 30° to the left and to the right, and usually 60° and 90° to both sides.   
   
b) Directional gyro: shows the aircraft's heading and, unlike the magnetic compass, it is absolutely stable and consequently much easier to use. However, in order to provide correct directional information, it needs to previously be aligned with the magnetic compass. This alignment can be carried out on the ground, where it is even a checklist item, as well as during flight. Just as the slightest up- or downward variation of the model aircraft on the attitude indicator reflects on the altimeter, ASI and VSI, a deflection in bank reflects on the directional gyro, showing a heading variation.   

c) Turn indicator: some designs, referred to as “turn coordinator”, look like an attitude indicator because, besides the ball, they also include a model aircraft (but which does not react to pitch attitude changes); others feature a vertical needle able to tilt left or right, and again the ball: these are referred to as "turn-and-bank" (a third type, of British manufacture and whereby the ball is replaced by a needle, is mostly found on vintage aircraft). The turn indicator shows the rate at which the aircraft changes its heading and is essentially designed for pure instrument flying, its only really useful part at this stage being the ball. Still, if you happen to notice either the model aircraft or the needle steadily deflected to one side, it means that the aircraft is turning toward that side.   

A lot more is to be said and understood about those three gyroscopic instruments. This will all be covered in groundcourses and during the advanced flight training. In fact, and particularly the attitude indicator and the directional gyro, provide you with exactly the same information than those obtained by use of external references. At this stage of your training, they must solely be considered as an additional aid to reach a high degree of accuracy. For the time being, and as was pointed out before, THE INSTRUMENT SCANNING MUST BE KEPT TO A STRICT MINIMUM SO AS NOT TO IMPAIR THE BASIC LOOK-OUT REQUIREMENT !!!   

 
If gyroscopic instruments are available, they should be checked for proper operation before departure:   

l°) As long as the engine is not running, these instruments are inoperative, unless they are electrically operated as is usually the case for the turn indicator. After the engine start, the suction indicator needle must at least be "alive", thus showing that the vacuum pump is operative, and the artificial horizon will gradually erect and stabilize in level attitude. Assuming that the model aircraft's nose (the center point between its “wings") is not located on the horizon bar, it can usually be adjusted by means of so-called pitch trim button. Once the engine is running, the directional gyro should be set in accordance with the magnetic compass.   

2°) During taxi, and only once the aircraft is clear of obstacles, the following checks should be carried out while causing the aircraft to zigzag somewhat: the indications of the artificial horizon must remain steady;   
   
- the directional gyro (and the magnetic compass) must deviate to the left when turning to the left, to the right when turning to the right;

- when turning to the left, the turn indicator' s needle must deflect to the left and the ball to the right, and vice­versa when turning to the right.
   
Note that if a venturi system is used instead of an engine driven vacuum pump, the indications of the associated instruments are likely to be unreliable as long as the aircraft is not airborne, because of lack of airflow.   

3°) During the engine run-up, the suction gauge should be checked "in the green" (unless a venturi system is involved).
   
4°) Prior to align the aircraft on the runway for takeoff, the directional gyro should be rechecked against the magnetic compass: both indications should still be very close from each other. If a significant difference should show, this is indicative of an unreliable directional gyro or of a failing magnetic compass.   

Let us take this opportunity to add the following:   

- The vertical speed indicator is supposed to read zero when the aircraft is parked on the ground. If not, the needle can be adjusted by gently tapping on the glass, or by means of a small adjustment screw which is usually located on the left lower side of the indicator (caution: this screw is extremely sensitive) .   

 
- Regarding the magnetic compass, it must be filled with alcohol in order to stabilize somewhat the magnetized needle (usually a ring magnet) . Leakage is not excluded and is likely to impair the system I s operation. Such a leak can be detected b the fact that the alcohol level becomes visible and/or that the graduations become discolored. Furthermore, and although this is a matter which will take full importance for navigation purposes, the magnetic compass must be accompanied with a recent deviation card (this will be discussed later) .   

C. - QUESTIONARY (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)  

01. - The lamp used by the traffic controller to give signals to aircraft is known as an  _____________ lamp.   

02. - The aircraft is on the ground. State the meanings of the following light signals:   

- Steady green ___________________________________________________
- Green flashes ___________________________________________________
- Steady red     _____________________________________________________
- Red flashes _____________________________________________________
- White flashes ___________________________________________________
   
03. - The aircraft is in flight. State the meaning of the following light signals:   

- Steady green ___________________________________________________
- Green flashes ___________________________________________________
- Steady red     _____________________________________________________
- Green flashes ___________________________________________________
- White flashes ___________________________________________________
   
04. - State the following meanings:   

- A single red flare   
- Red flares at ±10 seconds erupting in white stars or red and green fires   

05. - During the taxi, the carburettor heating system should be kept to COLD. Why?   

06. - Considering your training aircraft, you are taxiing with a wind of 20 knots. How do you position the stick with:

- full headwind     _________________________________________________

- full tailwind ______________________________________________________
- 90° crosswind ____________________________________________________
- crosswind from the front __________________________________________
- crosswind from the right __________________________________________

Explain why you act as described.
   
07. - In order to test the pedal brakes when beginning the taxi, it is not necessary to bring the aircraft to a full stop. True or false?
   
08. - You requested and obtained the clearance to cross an active runway during taxi. Which additional precaution should you take?   

09. - (POH) Considering your training aircraft:   

- magneto check at ________ RPM   
- maximum drop _______ RPM   
- maximum differential drop _______ RPM   
- idle ______ RPM   

10. - (POH) Considering your training aircraft, the static RPM is __________

11. - What do you understand by static RPM? What would happen if the static RPM would be in excess of the maximum allowable value?   

12. - You check the carburetor heating during the engine run-up. Which indication shows that it is operating correctly?   
   
13. - During the engine run-up, you notice that the carburetor heating is not operating correctly. The weather is warm and cloudless. Are you allowed to takeoff?
   
14. - Assuming that you fly with the carburetor heating in operation for an extended period of time, what should you do with regard to the mixture control? Why?   

15. - The carburetor heating should always be selected to COLD for takeoff. Why?   

16. - You are flying straight & level. The maximum allowable momentary deviations are _________ for the altitude, _________ for the airspeed, _________ for the heading.
   
17. - What do you understand by angle of incidence of a wing, or of a tailplane ?
   
18. - You are flying straight & level. You notice an RPM drop. The pitch attitude is definitely correct and the position of the throttle lever is unchanged. What happens? What should you do?   

19. - What do you understand by a trim tab. What is its use?   

20. - Trim tabs are sometimes replaced by small fixed aluminium plates. What are the three main disadvantages of these as compared to trim tabs?   

21. - What is the purpose of a balance tab? How does it work?   

22. - What is the purpose of an anti-balance tab? How does it work ?   
23. - You notice that the model aircraft on the attitude indicator is too high above the horizon bar and slightly banked to the left. What is to be expected regarding:   

- the airspeed indicator: ______________________
- the vertical speed indicator: _____________________
- the altimeter:    ________________
- the directional gyro:    _____________________
- the turn indicator: _________________

DON'T FORGET THE PILOT NOTES! UNLESS YOU DID IT ALREADY BEFORE. STUDY PARTICULARLY NOTES I AND IV. "BASIC PRINCIPLES OF LIGHT AIRCRAFT ENGINES". "LIGHT AIRCRAFT ELECTRIC SYSTEM"... AND DON'T FAIL TO ANSWER THE RELATED QUESTIONARIES!

ALDISLAMP SIGNALS/SIGNAUX LAMPE ALDIS   
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AIRCRAFT ON GROUND/AVION AU SOL
   
STEADY GREEN             YOU ARE CLERED TO TAKE OFF   
VERT CONTINU             VOUS POUVEZ DECOLLER   

STEADY RED                 STOP   
ROUGE CONTINU           STOP   

FLASHING GREEN         YOU MAY TAXI (YOU MAY CROSS THE RUNWAY)   
ECLATS VERTS            VOUS POUVEZ TAXlER (TRAVERSER LA PISTE)
   
FLASHING RED             VACATE THE RUNWAY   
ECLATS ROUGES          QUITTEZ LA PISTE
   
FLASHING WHITE          COME BACK' TO THE PARKING AREA   
ECLATS BLANCS            REVENEZ AU PARKING   


AIRCRAFT IN FLIGHT/AVION EN VOL

STEADY GREEN            YOU ARE CLEARED TO LAND   
VERT CONTINU            VOUS POUVEZ ATTERRIR
   
FLASHING GREEN         COME BACK FOR LANDING (USUALLY DURINGTOUCH-AND-GO SESSIONS WHEN A FULL STOP LANDING IS REQUESTED)   
ECLATS VERTS            REVENEZ POUR ATTERRIR (GENERALEMENT AU COURS DE CIRCUITS D'               ENTRAINEMENT SI UN ATTERRISAGE FINAL EST REQUIS)   

 
STEADY RED             GIVE PRIORITY TO ANOTHER LANDING AIRCRAFT AND MAKE AN OTHER CIRCUIT   
ROUGE CONTINU       DONNEZ PRIORITE D'ATTERRISSAGE A UN AUTRE AVION ET FAITES UN NOUVEAU   CIRCUIT   

FLASHING RED           LANDING PROHIBITED AT THIS AIRPORT   
ECLATS ROUGES        ATTERRISSAGE NON AUTORISE SUR CET AEROPORT   

FLASHING WHITE       YOU MUST LAND ON THIS AIRPORT (USUALLY WHEN THE AIRCRAFT HAS BEEN       INTERCEPTED)   
ECLATS BLANCS         VOUS DEVEZ ATTERRIR SUR CET AEROPORT (GENERALEMENT APRES AVOIR ETE     INTERCEPTE)   

FLARES/FUSEES
   
RED FLARE: LANDING PROHIBITED (USUALLY WHEN A PREVIOUS RED LIGHT   
HAS BEEN DISREGARDED)   

FUSEE ROUGE: INTERDICTION D'ATTERRISAGE (GENERALEMENT LORSQUE UN   
SIGNAL ROUGE CONTINU A ETE NEGLIGE   

FLARES FIRED AT 10" INTERVALS WITH ERUPTION OF WHITE OR RED AN   
GREEN COLORED STARS: PROHIBITED AREA   

FUSEES TIREES A 10" D'INTERVALLE AVEC ECLATEMENT D' ETOILES   
BLANCHES OU ROUGES ET VERTES: ZONE INTERDITE

A .- BRIEFING (01,00 h. - Total 07,00 h.)   

During the previous flight sessions, you had already the opportunity to notice that a turn is mainly achieved by banking the aircraft in the required direction. In other words, a turn is carried out by means of the ailerons and not, as the Flemish and French terms "richtingsroer" and “gouvernail de direction" might imply, by means of the rudder. However, this does not mean that the rudder, and even the elevator, play no part in the turn. Quite the contrary: a correct turn is the result of the coordination of all these control surfaces, as well as of the engine's thrust.   

As was pointed out earlier, when the aircraft is banked by means of the ailerons, say to the left, the lift vector also tilts to the left and decomposes into two components, a vertical one Fz’, and a horizontal one which causes the aircraft to turn towards the low wing (fig. 1).   

The horizontal component is in fact the centripetal force (mid-,denpuntzoekende kracht/force centripète), by which the aircraft tends to move towards the center of the turn and which, in combination with the forward motion, gives way to a gradual direction change to the left. The appearance of the centripetal force with the bank angle is also the reason why it is necessary to keep the wings level to maintain straight flight.   

It is obvious that the flight direction also changes when the rudder is used, but recall that rudder input instantly causes the aircraft to skid outwards of the turn, and this skidding motion is not only quite unpleasant for the occupants but, as we shall see later, it might even become rather unsafe. On the other hand, we know that when the aircraft is banked it has a tendency to slip. However, this tendency is less pronounced, and develops only when the bank angle is excessive compared to the airspeed   and the radius of the turn.   

We might conclude from the previous that, in order to perform a correct turn, only the ailerons should be used to achieve the adequate bank angle, were it not for a first particularity: the aileron drag. Recall that the downgoing aileron tends to induce an opposite yaw motion. For instance in a turn to the left, the downgoing right aileron gives way to a yaw to the right and a resulting tendency for the ball to deflect to the left. As a consequence, some left rudder is required to cancel this tendency. It is true that the effects of the aileron drag is usually rather weak, particularly at normal cruising speeds where it is hardly noticeable, so that the required rudder input is mostly very small. However, as we shall see during the next lesson, propeller effects also play a part, and the dosing of rudder input may vary somewhat depending on whether the turn is carried out to the left or to the right (for a clockwise rotating propeller, as seen from the cabin, the need for rudder is less - perhaps even nil – for a turn to the left). At any rate, the coordinated use of stick and rudder is a first requirement to obtain a perfect turn.
Figure 1 shows clearly that the vertical component FZ’ becomes ever smaller as vector Fz becomes more tilted. The problem is that it is FZ’ which is supposed to counteract the weight G (see also fig. 2) and, as the weight remains unchanged, it is obvious that the aircraft tends to loose altitude when it is banked, and more so as the bank angle increases. It is thus necessary to maintain Fz' at the same value than the weight: this is achieved by pulling on the stick, i.e. by increasing the angle of attack, thus increasing both Fz and its vertical component Fz’ (and consequently also the centripetal force, a fact on which we will come back later, when studying the steep turns). The use of the elevator is the second aspect of turn coordination.   

However, we know that increasing the angle of attack does not only increase the lift, it also increases the drag. In other words, pulling on the stick during the turn causes the airspeed to decrease: it is thus necessary to increase the engine’s thrust to avoid this. The use of the throttle lever is the third aspect of turn coordination.   

Once the turn is correctly established, all forces acting on the aircraft are in equilibrium (fig. 2): the vertical component Fz' equals weight G so that the altitude remains unchanged, the thrust equals the drag so that the airspeed remains steady, the centripetal force Fz is equal and opposite to vector Fy, representing the centrifugal reaction, so that the ball remains centered, and- the lift vector Fz is exactly opposite to force GI. This force GI is known as apparent weight (schijnbaar gewicht/poids apparent), or load factor (belastingsfactor/facteur de charge), or even more simply: ß. Load factors will be further discussed later, amongst others when covering the steep turns.   

Turns are classified as shallow until a maximum of 15° of bank angle, medium between 15° and 30°, and steep when the bank angle exceeds 30°. A fourth variation is the so-called maximum performance turn, a manoeuvre more closely related to aerobatics than to normal operations, and which implies turning within as small a radius as possible, using the lowest possible speed with the maximum possible bank angle. At this stage, we will discuss only shallow and medium turns, steep turns and maximum performance turns will be covered later.   

Let us begin with a first but very important statement: never fail to look out before initiating a turn, particularly in your rear quarter. and continue looking out while in the process of turning. This is vital, and certainly in the immediate vicinity of an airport where a lot of traffic may be expected. The trouble with high wing aircraft, such as most Cessna types, is that the view is seriously impaired during the turn: in this case, it is certainly imperative to watch for other aircraft before initiating the turn, possibly lifting the wing somewhat to ensure that the area is free.   
   
All turns, from shallow to steep, are executed according to the same principles: they must be coordinated so that the aircraft stays in equilibrium at all times, without slipping or skidding, at a constant bank angle, and without altitude variations. For shallow and medium turns, the airspeed should remain unchanged. No large movements of the stick or rudder are required: this would only lead to overcontrol. In fact, the required pressures on the flight controls are so light that an observer sitting besides the pilot can hardly notice any of these inputs. Let us assume a turn to the left: - LOOK OUT!!!
   
- Very gently apply stick to the left to initiate the roll motion, and simultaneously depress the left rudder pedal somewhat to anticipate the aileron drag. However be aware that, particularly for shallow turns and at normal cruising speed, the aileron drag is so little that the use of the rudder can practically be disregarded. Nonetheless, watch the ball and keep it centered: if it deflects to the left, a small pressure on the left rudder pedal will bring it back to center; should it deflect to the right, the rudder input was too strong: reduce it !
   
- As the aircraft banks toward the required angle, the resulting loss of lift should be anticipated by slightly pulling on the stick, but also this correction is practically to be disregarded for shallow turns. Watch the nose: during shallow turns, the pitch attitude is practically the same as for straight & level flight, whereas for medium turns it might be just slightly higher to maintain the altitude. Achieving the correct pitch attitude by the use of external references must nonetheless be combined with successive and momentary crosschecks of the altimeter and the variometer and according to their indications, gently correct the pitch attitude as needed, but don't keep staring at these instruments;   

- Have now a look on the airspeed indicator: remember that if you pulled on the stick, even slightly, to increase the angle of attack, the airspeed will inevitably decrease. As soon as you notice this, increase thrust somewhat to maintain or to re-adjust the required value. In fact, this speed decay can be   anticipated as well by increasing the thrust before it shows, but this must be done very carefully: many times pilots advance the throttle lever too much, which results in an increasing airspeed, usually combined with an unwanted altitude gain;   

- Once the required bank angle is obtained and that the aircraft is in equilibrium as shown in figure 2, one might believe that both the ailerons and the rudder may be brought back to their neutral position (obviously not the elevator). Basically, this is true, but the fact that the outside wing develops a higher angular speed than the inner one I thus more lift, there is a tendency for the bank angle to increase: therefore, in order to maintain the bank angle unchanged, it might become necessary to cancel this tendency by applying somewhat stick to the right;   
   
- Note that, as a turn is normally a transient manoeuvre, the elevator trim should be left untouched during its execution;   

- To exit the turn, simply bring the stick gently back to neutral, keeping the ball centered with rudder as required. However, pay attention to the following two factors which, again, are hardly noticeable when a shallow turn is involved:   

1°) when rolling out of the turn, the angle of attack which was increased during the turn must again be reduced accordingly by moving the stick forward. Failing to do so will result in a nose high attitude in straight flight with consequent altitude increase and speed decay;   

2°) also the throttle lever should be retarded to re-adjust the thrust to normal cruise value.   

Finally, remember the following:   

- as far as the ball is concerned, it should be kept centered by means of the rudder. Remember: left rudder, ball deflects to the right, right rudder, ball deflects to the left;

- if, during the turn, you notice that the ball is off center, apply rudder according to the principle here above . . . . . . . . . . but keep in mind the secondary effects: be aware that any rudder input also affects the bank angle and requires a correction on the ailerons to keep it unchanged.

Assuming that you wish to roll out in a specific direction, the manoeuvre must be initiated in due time, about 5° to 10° in advance, so that the wings reach the level attitude at the very moment that the nose points in the required direction.
   
Direction changes of 90° can be executed by means of a mark in the prolongation of the wing tip (this mark can be a landmark or a distant cloud). For a direction change of 180°, take first a mark at 90° and, when the nose passes it, take a second one at 90°, at least in so far that the view is not impaired by the wing (which, as said, is unfortunately one of the major disadvantages of most high wing light aircraft). A similar procedure, which incidentally profits to the look-out, is valid for 270° and even 360° turns, although the latter can be carried out by picking up a mark in front and rolling out when it shows up again.   
   
You have probably already noticed several times the term QNH, either in relation to meteorological information, or during radiotelephony procedures. During the first lessons, your instructor will most probably have drawn your attention to the altimeter's associated barometric window, calibrated in millibars (and usually also in inches), and to the barometric setting knob.   
   
The full explanation regarding the QNH will be given during the groundcourse. Simply stated, QNH means the air pressure at sea level. In the early years of aviation, when radiocommunications still happened in Morse (in those times there was a radio operator on board, along with the pilot) and that it was necessary to keep the "talking" as short as possible, the so-called O-code was introduced. This code included the most diverse expressions, not only concerning weather information, but also with regard to various other subjects, each one composed of three letters, and always beginning with Q. The Q-code is thus a simple convention. For instance, besides QNH, we have the terms QFE referring to the air pressure prevailing at the airport's elevation, QNE for the standard air pressure at sea level, QGO meaning that the airport is closed, etc. You will also encounter it later, in relation to radionavigation, with such expressions as QDM, QDR, etc. Although the Morse-code is no longer of use for radiotelephony, the Q-code remained with still the same purpose: shortening the transmissions.   

The altimeter is in fact a simple aneroïd barometer (metaalbarometer/baromètre anéroïde) graduated in feet, and reacts to variations of ambient air pressure with altitude: when the altitude increases the pressure decreases and the altimeter indication goes up, and vice-versa. However, the ambient air pressure does not vary solely with the altitude: it is a well known fact that it also changes locally. In other words, even if it remains motionless on the ground, the altimeter will show differently at different moments because of these local pressure changes. This is why the instrument is fitted with a setting knob by which the position of the needles can be changed together with the indicated barometric pressure. In fact, the altimeter can be caused to read almost anything. Note that the instrument is designed in such a way that if the barometric setting is increased the altimeter will show higher, and vice-versa, at the rate of 30 feet for each millibar (or hectopascal, which is exactly the same thing) difference.   

As far as its practical use is concerned, when the aircraft is on the ground and that the altimeter is adjusted to read zero feet, the associated indicated barometric pressure is the value prevailing at the airport, or the OFE. After takeoff, and as long as there is no change in the weather situation, the altimeter will then show the correct elevation above the departure airport, but not necessarily overhead any other other place where the barometric air pressure might be different.
   
The QFE is rarely used nowadays, the normal setting being the QNH (you will learn later that, for navigation flights at an altitude in excess of the so-called transition altitude, another setting will be required, namely the so-called standard setting of 1013,2 millibars). As said previously, the QNH is the barometric pressure prevailing at sea level or, to be more explicit, it is the barometric pressure measured at the airport's elevation, and increased to sea level value at the rate of one millibar for each 30 feet of elevation (the same rate used for the altimeter's mechanism). When the aircraft is on the ground and that the altimeter's barometric setting is set to read the QNH, the instrument shows the elevation above the sea level, or conversely, if the altimeter needles are adjusted to the airport elevation, the barometric window will show the QNH.   

To clarify somewhat the previous, let us assume that the airport is located at 300 feet above sea level and that the local barometric air pressure, thus the QFE, is 1000 millibars (mb):   

a) if the altimeter's barometric setting is adjusted to 1000 mb, it will read zero feet; conversely, when causing the altimeter to read zero feet, the barometric window will automatically show 1000 mb;   

b) if the altimeter needles are adjusted to 300 feet, the barometric window will automatically read 1010 mb (10 times 30 ft); again conversely, if the barometric setting is adjusted to 1010 mb, the altimeter's needles will show 300 ft.   


B. - FLIGHT TRAINING (Dual 01,00 h. - Total 04,00 h.)

   
You will again perform all required handlings and checks before departure and after landing. This time, emphasize the associated instrument checks prior to departure.   

You will again fly the aircraft from takeoff until landing as before, save for some possible brief relaxing periods allowed by the instructor if need be.   

Once established in straight & level cruise, the instructor will take over the controls to demonstrate and comment turns to both sides and the associated roll outs, emphasizing the look-out. Each demonstration will begin with a sustained shallow turn, giving you ample time to notice the bank angle, the nose attitude in relation to the ground and the throttle setting, then the bank angle shall be increased to medium value, which also will be held steadily for a while, until the roll out will be initiated. Note in particular the very small flight control inputs.   

The instructor will also draw you attention to the indications of the gyroscopic instruments, particularly of the attitude indicator.   

A further demonstration will show you the most usual errors, for instance what happens when too much or too little rudder is applied and how to correct it, what happens during the rollout when the pilot fails to reduce the angle of attack, etc.
   
You will then be requested to execute yourself a few turns to both sides, initially rolling out upon request of the instructor in whatever direction, next rolling out after exactly 360°, using solely external references. Think about looking out I particularly in the tail area before initiating the turn, and also during the turning process itself. Remember that you must mainly use external references, and only very intermittently watch the various instruments and the ball as an additional check. Don't get tense because you notice same minor variations in altitude or airspeed: nothing wrong with that, provided that you gently apply corrections as required.   

Finally, try to keep track of your position in relation to the airport: many students, and even trained pilots, experience very serious difficulties to determine the direction of their home base after a number of turns... and be sure that the instructor will request you to do so.   


C.    - QUESTIONARY    (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)  


01. - An aircraft which is banked to the left has a tendency to alter its direction towards the left. Why?   

02. - State the function of the rudder when initiating a turn.   

03. - The aircraft is established in a level turn to the left. The bank angle: a) tends to remain steady, b) tends to increase, c) tends to decrease   

04. - The aircraft tends to loose altitude during a level turn. Why?   

05. - The aircraft tends to loose airspeed during a level turn. Why?   

06. - The elevator trim should not be used during a turn. True or false?   

07. - Make a drawing of the forces acting on an aircraft during a level turn.   

08. - A shallow turn implies a maximum bank angle of _____° A medium turn implies a bank angle between ____° and ____°   

09. - During a turn to the left, you notice that the ball is deflected to the left. To recenter it, you should depress the rudder to the _______. And what about the stick?
   
10. - You wish to turn toward a specific direction. You should initiate the roll out about _____° before reaching it.   

11. - You wish to change direction by 900 to the left. How do you determine the new flight direction with external references?   

12. - Besides the direction in which you rollout of a turn, state two factors which must be kept in mind to maintain straight & level flight at uniform speed.
   
13. - State the difference between QNH and QFE. Which of these is normally used?   
   
14. - Aircraft on ground. The airport is located at 1200 feet above sea level. The reporter QNH is 1020 millibars. You select 1020 in the barometric window. The altimeter shows:   
a) zero feet, b) 1200 feet.

15. - Referring to previous question, the value of the QFE equals _________ mb.   

16. - Referring to question 14, if you select the QFE in the barometric window, the altimeter will show: a) zero feet, b) 1200 feet.   

17. - The airfield is located at 300 feet above sea level. The altimeter is set on the local QNH and indicates 1000 feet when passing overhead. The aircraft's elevation over the airfield is: a) 700 ft, b) 1300 ft, c) 1000 ft.   

18. - You put the aircraft in the hangar for the night. At that time, the altimeter read the airport elevation of 450 feet with 985 mb set in the barometric window. The next morning, the altimeter shows 390 feet, still with the setting- of 985 mb. The prevailing barometric pressure has: a) increased by ________ mb, b) decreased by _______ mb   

19. - What is the purpose of the Q-code? What is its origin?

A. - BRIEFING (01,00 h. - Total 08,00 h)

The sketch in lesson 03 representing the four forces acting on an aircraft in straight & level flight has been somewhat simplified. In reality, and because of a number of design properties, there is a couple between thrust and drag, as well as between lift and weight. On most aircraft, the structural design is such that the thrust line is lower than the drag line; on the other hand, the weight acts always through the center of gravity whereas the lift's line of action is located behind it. Figure l shows an improved drawing of the four forces.

Because of the interaction between these two couples, a nose up tendency will occur whenever the engine thrust is increased. Conversely, a thrust reduction results in a nose down tendency. In other words, whenever the thrust setting varies during level flight, the elevator must be used to counteract the resulting pitch attitude variations.

Let us now assume that the thrust is increased by pushing the throttle lever forward, and that we prevent the nose from pitching up by use of the stick: as the thrust is momentarily higher than the drag, the airspeed will increase and will continue to do so until the drag catches up, at which moment the airspeed stabilizes at a higher value. But there is more to it: because of the higher airspeed, the lift will also increase and the aircraft tends now to gain altitude. If we want to maintain the altitude unchanged, it becomes necessary to decrease the angle of attack in order to eliminate this excess of lift. In other words, if we want to increase the airspeed in level flight, obviously we need to open the throttle lever to increase the thrust, but this implies a forward correction on the stick, firstly to counteract the effect of the couple, secondly to eliminate the surplus of lift.

Conversely, assuming a thrust reduction and that we prevent the nose from pitching down by use of the stick, the thrust will momentarily be less than the drag, the airspeed will decrease and will continue to do so until the drag equalizes again the reduced thrust, at which moment the airspeed stabilizes at a lower value. However, this time the lift decreases because of the reduced airspeed and the aircraft looses altitude. In order to maintain the altitude unchanged, it is now necessary to compensate this loss of lift by increasing the angle of attack. In other words, if we want to decrease the airspeed in level flight, the throttle setting should be diminished to decrease the thrust, but this implies an aft correction on the stick, firstly to counteract the effect of the couple, secondly to compensate the lack of lift.

The conclusion of these phenomena is that in level flight at higher airspeeds, the aircraft flies in a nose down attitude, whereas lower airspeeds are giving way to a nose up attitude (fig. 2). Needless to add that, for any required airspeed, the elevator trim needs to be correctly adjusted so that the stick can be released and that the pitch attitude remains unchanged.

The maximum airspeed in level flight is of course a function of the maximum power which can be developed by the engine. On the other hand, the minimum airspeed is a function of the angle of attack. Indeed, this angle cannot be increased forever: fact is that when it reaches a value of about 16°, depending on the shape of the wing profile, the airflow over the wings is no longer smooth and steady, but becomes turbulent. This phenomenon produces a considerable increase of drag combined with a decay of lift, and rapidly leads to a situation whereby the aircraft is unable to remain airborne and starts to fall. This is known as the stall (afscheuren te wijten aadraagkrachtverlies/décrochage dû à la perte de sustentation), which will be fully discussed at a later stage.

Let us clarify somewhat the term "wing profile" mentioned here above. An endless list of various wing profiles suited for all sorts of aeroplanes, has been catalogued by a number of organizations. One such organization is the American National Advisory Committee for Aeronautics, or N.A.C.A. For instance, the POH of the Piper PA-28-161 Cherokee Warrior II, anna 1976, mentions that the aircraft's wing profile is a NACA 652415: these series of ciphers identifies the various specifications of the profile such as its curvature, its length, its thickness and other details. Although the wing profile specification details are of mere academic nature to the pilot, these are very important to the aircraft manufacturers because they ' determine various wing’s general properties, amongst which for example the angle at which the stall will occur: one type of wing will be stalled at 16° angle of attack, another one perhaps at 14° or 15°, and a third one maybe at 20° or more.

A choice of airspeeds between the maximum and the stall speed, together with associated power settings, is thus available to the pilot. During training, a standard power setting determined by the instructor is mostly used for cruising flight. Nonetheless, be aware that for operations other than training, different settings may be selected, depending on whether maximum range, maximum endurance or maximum speed is required. Although this theory is premature for the time being, we recommend you to have a closer look at the part "PERFORMANCES" in the POH of your training aircraft.

The aim of this lesson is to learn you to fly at various airspeeds while maintaining a given altitude. You will notice that, in order to fly at the lower airspeeds, despite that is is necessary to reduce power to attain these speeds, once they are reached it becomes necessary to significantly increase the thrust again so as to maintain the required lower value. This particularity is due to the fact that, as pointed out previously, a low airspeed requires a high angle of attack to compensate for the decaying lift but this also inevitably increases the drag: this higher drag value demands a compensation which can only be provided by a higher thrust.

Another particularity of flying at low airspeed is that the ailerons loose quite a bit of their efficiency (and, incidentally, aileron drag becomes much more pronounced) as compared to the other control surfaces. This is the direct result of the lower speed, and is a first indication of an impending stall. The elevator and the rudder, being located within the propeller's slipstream, are much less subject to such an efficiency loss.

Talking about the propeller I s slipstream, it becomes time to introduce you to the various propeller effects. These are fully described in PILOT NOTE II: "THE AIRCRAFT PROPELLER AND ITS EFFECTS" (if your training aircraft is fitted with a fixed pitch propeller, you may disregard the theory about variable pitch propellers at this stage... but keep in mind that you will most probably be involved with these during the advanced flight training).

Propeller effects are ever present in one form or in the other. Till now, you probably did not clearly notice them, except perhaps during turns where the required rudder input is slightly different depending on whether you turn to the left or to the right or, if your training aircraft is fitted with a tail-wheel, by the fact that some rudder is required when raising the tail during the takeoff roll. At any rate, in flight, and as long as normal cruising airspeeds are involved, these effects are practically unnoticeable for the very simple reason the manufacturer tries to eliminate them by all kind of technical tricks. They will mainly be felt at the lower airspeeds, by the fact that they produce a significant unwanted yaw tendency: to the left when the propeller, as seen from the cabin, turns clockwise, which is the case for most American power plants, to the right when the propeller turns anti-clockwise, as is the case for most British built engines.

Propeller effects are fourfold: torque. slipstream. P-factor and gyroscopic effect. Torque and gyroscopic effects are mainly involved during the takeoff phase, particularly for tail-wheel equipped aircraft. Slipstream and P-factor are as well, but these are particularly responsible for the yaw tendency when flying at low speed and high angle of attack: you will notice that, besides the previously described requirements, you will need quite some rudder input to maintain the heading unchanged and the ball centered. Also, during turns at low airspeed, you will clearly notice the difference in "rudder dosing" to the left and to the right.

Note that as far as turning at low or high speed is concerned, the procedure is exactly the same as for normal cruise speed, except that:

1°) the nose attitude is different;

2°) the rudder inputs are significantly different, particularly at slow speed, whether turning left or turning right;

3°) for turns at slow speed, the bank angle should always be shallow to avoid stalling (see below).

Flaps. slots and slats

Any specific wing design can be "adapted" to delay the appearance of turbulent airflow, and thus allow lower airspeeds. The means to achieve this are flaps, slots and slats:

a) Flaps (vleugelkleppen/volets hypersustentateurs);

The flaps are located on the wing's trailing edge, between the fuselage and the ailerons. They are either mechanically, electrically or hydraulically activated, and can usually be extended downward in several positions. Although a lot can be said about flaps, it should be noted that, by modifying the general shape of the wing profile, a small extension produces a significant increase of lift for only a very small increase of drag, and gives way to a lesser stalling speed than with flaps retracted. This is why, at lower airspeeds, such as during the approach procedure, the flaps are partially extended to improve the safety margin against the stall. Although the additional drag is very small, the partial flaps extension gives way nonetheless to some airspeed decay which must be kept under control by increasing the thrust as needed. Note also that, because of the lift augmentation, partial flaps is used under certain circumstances for takeoff as well: this will be discussed later.

When the flaps are selected to the full down position, the drag augmentation is considerable, but note that a very small additional lift increase still occurs: this minor lift increase will prove extremely important later on. The full down position of the flaps is only used for landing, which also will be fully covered at a later stage.

Extending the flaps often gives way to a marked pitching motion of the aircraft, usually a nose up tendency, but sometimes a nose down trend: this again depends on the aircraft's design. Obviously, retracting the flaps causes the reverse effect. At any rate, the resulting pitching must be neutralized by means of the elevator.

Due to structural considerations, there is a maximum allowable airspeed to extend the flaps. This value depends on the aircraft type, and is referred to as Vfe, for "Velocity Flaps Extended". This limiting airspeed is represented on the ASI by the upper limit of the white arc, whose full purpose will be discussed hereafter. Note that on some aircraft, a specified partial flaps selection is authorized at a higher airspeed than the white arc's upper limit: this possibility must be reported in the POH, and must also be placarded on the instrument panel.

b) Slots (spleten/fentes);

Some aircraft are fitted with so-called slots built into the wing's leading edges. Slots are permanent, i.e. they cannot be opened or closed at will. They become effective only at high angle of attack, and allow a part of the airflow to pass through them. This results in a delayed appearance of turbulence, and consequently in a significantly lower stall speed. The main drawback of slots is that, as they are permanent, they cause quite some drag when flying in normal cruise attitude which, of course, results in a lower cruising speed far a given power setting. This latter problem is eliminated by the use of slats.

C) Slats (????/becs de bord d'attaque);

The forefront part of the wing’s leading edges is sometimes movable and forms the so-called slats. At normal angles of attack, the slats literally stick onto the leading edges so that no drag producing slot is present. At high angle of attack, the slats slide forward of the actual leading edge, thus creating a slot as described here above.

On light aircraft, such as for instance on the French Morane-Saulnier, the slats are usually automatically activated when the angle of attack reaches a certain value, under influence of.the pressure distribution over the wing: as soon as the angle of attack is decreased, the slats slide back and form again one single unit with the wings. The unpleasant thing with automatic activated slats is that they repetitively tend to open and noisily slam back in close position when the aircraft is at certain “critical” angles of attack when flying at reduced airspeed during the approach procedure, particularly when weather conditions are somewhat turbulent. Slats (often in combination with leading edge flaps) are absolutely essential for heavy jets, in which case they are operated by the pilot.

A combination of these various techniques is of course possible, anyone of which can be used on the lightest as well as on the heaviest aircraft. Just for information, besides slats, many heavy jet aircraft are also fitted with a number leading edge flaps sections, known as Krüger flaps, whose sole purpose is to increase the curvature of the wing.

Symbology on the airspeed indicator

You certainly have noticed that the ASI features a number of coloured arcs as well as a red mark. The meaning of these various symbols is as follows:

- White arc

Speed range in which the flaps may be fully extended without causing any damage. The lowest limit represents the so-called Vso. This is the stall speed in landing configuration, i.e. with the flaps fully extended (and assuming a retractable landing gear, with the wheels down). Note that the indicated stall speed is only valid for a number of specific conditions, namely: maximum landing weight (which, for light aircraft, is usually the same as the maximum takeoff weight) I maximum forward position of the center of gravity, wings level, a load factor of lG, and the engine at idle power. These various conditions will be further discussed at a later stage.

The term “Vso” stands for "Velocity Stall" (Vs), the letter “o" referring to the landing configuration. The stall speed under any other configuration, whether the flaps are retracted or only partially extended, or that the gear is retracted, is referred to as Vs, without additional subscript. The difference between Vso and Vs is, for some reason, a matter of convention typical for propeller driven aircraft: no such difference is made for jet aircraft where the stall speed in any configuration is referred to as Vs.

- Green arc

Speed range in which the aircraft can be safely operated with flaps retracted. The green arc usually overlaps the white speed range somewhat. Its lowest limit is the stalling speed in clean configuration, i.e. with flaps (and if such should be the case, the landing gear) retracted. This is not the Vso, but a Vs (see above) and, also for this Vs, the other conditions mentioned for the Vso are applicable.

The highest limit is the so-called maximum structural cruising speed, also referred to as Vno, i.e. the maximum "Velocity for Normal Operation". Vno may not be exceeded, except in smooth air conditions. Note already that Vno is NOT the so-called

manoeuvring speed (see below) .

- Yellow arc

The yellow arc begins at the upper limit of the green one. It represents the so-called caution range in which operations may only be conducted in smooth air. Note that under conditions of heavy turbulence, another maximum speed. and WHICH IS NOT MARKED ON THE AIRSPEED INDICATOR, must be taken into consideration. namely VA. or maneuvering speed, which we will discuss later.

- Red mark

The red mark is located at the upper limit of the caution range and represents the airspeed which may not be deliberately exceeded under any circumstances. It is referred to as Vne, or "Velocity Never Exceed".

Besides the previous mentioned ones, there are several other so-called "V-speeds" for which there is no mark on the airspeed indicator. Assuming that your training aircraft is fitted with a retractable landing gear, you must know the value of:

- VLo, for "Velocity Landing gear Operating": this is the maximum speed at which you may initiate the extension or the retraction of the wheels... and note that very often there are two VLo's, one for the extension, and a different one for the retraction;

- VLe, for “Velocity Landing gear Extended", i.e. the maximum allowable speed with the landing gear locked in down position.

In the next lesson you will be introduced to Vy and Vx and, once we will be discussing the landing procedure, with the Vref, or reference speed.

Stall demonstration

Although the stall will be fully discussed later, the instructor will take the opportunity of flying at low speed to introduce you to its effects during this flight session, once in clean and once in landing configuration. During these demonstrations, he will first draw your attention to the extreme nose high attitude, and want you to have a look to the resulting angle of attack of the wings. Notice further the following:

- The speed at which the stall warning system is activated. The stall warning system can be a pneumatically operated horn sounding about 10 knots before the actual stall. The horn can also be electrically operated through a lip located on one of the wing leading edges and which moves upward when the angle of attack approaches the stall value.

- The speed at which the aircraft begins to shake: this is the so-called buffeting, which is not necessarily very marked on some aircraft, and which is due to the fact that the airflow over the wings becomes turbulent.

- The indicated airspeed and the aircraft's behaviour at the very moment of the stall: the nose pitching suddenly down, possibly combined with and equally sudden rolling motion.

- Keeping the aircraft in stalled condition, the instructor will also draw your attention to the fact that, despite the initial nose down motion, the indicated airspeed does not build up and remains close to the stalling value.

On some aircraft, the stall can be a rather abrupt affair. However, on most light trainers it is much less so and, on some types, the nose does not even pitch down noticeably: the aircraft simply starts sinking at a rather high rate of descent, while the aircraft waggles somewhat around its longitudinal axis.

In order to exit a stalled condition, all which is needed is to move the stick forward somewhat to decrease the angle of attack, and the aircraft is immediately back under control. Although deliberately stalling an aircraft at low speed, from straight & level flight and at a safe altitude is a non-event, the very first experience may be somewhat impressive but, as said, there is no cause for concern whatsoever.

B. - FLIGHT TRAINING (01,00 h. - Total 05,00 h.)

Once at cruising altitude you will initially fly straight & level at normal cruise for a few minutes. The instructor will then request you to carry out a few 90° or 360° medium turns to the left and to the right. Upon completion of these revision exercises, verify once more that the aircraft is still correctly trimmed.

To make you aware of the influence of the couple between the four forces, the instructor will now ask you to leave the stick untouched; he will then select the carburetor heating to HOT: observe the RPM drop and the subsequent tendency (albeit very little at this stage) for the nose to pitch down. Next, still with the stick released, closely watch the aircraft's nose as the instructor sharply reduces power to idle: observe the marked further pitch down and, usually less conspicuous, the tendency to yaw to one side: notice the altimeter decreasing, the ASI gradually increasing (or at least not decreasing any further despite the power reduction), and the ball deflected opposite to the yaw.

Notice also the VSI showing DOWN, the model aircraft on the attitude indicator, the effect on the turn indicator and the varying indication on the directional gyro.

You will then be requested to take over the flight controls and to resume straight & level flight at normal cruise power with the carburettor heating back to COLD: do this mainly by using external references with an occasional glance at the various instruments. As you will have lost some altitude and that the heading has probably changed somewhat, no need to go back to the previous altitude and heading: simply maintain the new values.

You will now again be asked to leave the stick untouched, this time to observe the reverse effects while the instructor now sharply opens the throttle lever to maximum power: pitch up! Yaw in opposite direction! Note the behaviour of the ball and the various instrument indications. Upon request, take over once more and stabilize again the aircraft in straight & level flight.

Notice the altitude and the heading. You will now be instructed to reduce power gradually but firmly to idle (don't forget to re-activate the carburettor heating previously), this time avoiding the nose to pitch down by smooth action on the elevator (no trimming required at this stage) as the airspeed decreases, and keeping the direction unchanged, thus the ball centered, by action on the rudder: only gradual pressures on the stick and on the rudder are required. Again, use mainly external references, checking only occasionally the various instruments.

Once the airspeed has dropped in the vicinity of the green arc's lower limit, the instructor will request you to open up to full throttle, again firmly but without brutality, and to select the carburettor heating back to COLD. Be prepared to counteract the pitch up and reversed yaw tendencies the same way as you did when decreasing the power. A word of caution here: assuming a fixed pitch propeller, remember that as the airspeed increases, so does the RPM. Consequently, when approaching the maximum speed it might thus be necessary to reduce the power setting somewhat to keep the RPM within its maximum limit.

Still in straight & level flight, you will now be asked to maintain a specified airspeed close to the maximum and to adjust the trim accordingly. You will then be instructed to execute one medium turn to the left and one to the right.

When again straight & level, you will be asked to reduce in steps to various specified lower airspeeds, initially to normal cruise value, then to the so-called circuit speed (usually the upper limit of the white arc), finally to a speed of ±10 knots above the stall in clean configuration, each time re-adjusting the trim accordingly. At this last stage, notice the rather high power required to maintain the speed, the significant nose up attitude, and have a look at the angle of attack of the wings.

At this slow speed, you will be asked to perform a shallow turn to the left and one to the right: notice now the sluggishness of the ailerons and the significant difference in rudder input between left and right turns to keep the ball centered.

The instructor will then take over the controls and will now demonstrate the stall. Notice the airspeed at which the stall warning system is activated, the possible buffeting, the airspeed at which the stall actually occurs, the aircraft's behaviour and the sustained low speed indication. Having recovered, he will lower the flaps completely (as well as the landing gear, if retractable) and again gradually reduce the speed until a second stall occurs, this time in landing configuration: note the lower speeds at which stall warning, buffeting and actual stall take place.

Following this demonstration, the instructor will stabilize and trim the aircraft himself, back in clean configuration, and at a speed within the white arc. He will then ask you to leave the stick untouched once again, and to select the flaps partially down, then back to up, and to notice the reactions of the aircraft around its pitch axis.

Normal cruise will now be resumed and, time permitting, some additional speed varying exercises will be carried out before or while returning to the home base. You will once again be "nursed" by the instructor through the descent and approach procedure to the landing. At any rate, at some stage you will be requested to reduce to the so-called circuit speed, to lower the flaps to some 10 (depending on the aircraft type), to readjust the throttle lever so as to maintain the speed unchanged and... to perform by heart the approach checklist (as well as the final checklist once aligned with the landing runway) yourself: REVIEW THESE CHECKLISTS!!!

C. - QUESTIONARY (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)

01. - Make a drawing of the four forces acting on an aircraft in straight & level flight, taking into consideration the action lines and couples between these forces.

02. - How does the aircraft react on the pitch axis: a) when increasing power, nose ____, b) when decreasing power, nose _____

03. - Explain why an aircraft flies "nose down" at high speed and "nose up! at low speed.

04. - The limiting factor for the maximum airspeed in straight & level flight is ____________; for the minimum speed it is _____________

05. - The average maximum value for the angle of attack is _____°

06. - The direct cause of the stall is: a) low airspeed, b) high angle of attack, c) turbulent airflow over the wing.

07. - Rather high engine power is required to maintain a low airspeed. Why?

08. - When flying at low speed, the ailerons become significantly more sluggish than the elevator and the rudder. Why?

09. - N.A.C.A. stands for __________________________________________________

10. - State three ways to "adapt" a wing design so as to reduce the stall speed. Which of these means are available on your training aircraft?

11. - Row does lift and drag behave: a) at a small flaps deflection, b) at full flaps deflection?

12. - (POH) Assuming that your training aircraft is fitted with flaps, their maximum deflection is ____°

13. - (POH) Assuming that your training aircraft is fitted with flaps, they are operated: a) manually, b) electrically, c) hydraulically d) pneumatically.

14. - The flaps are usually partially lowered during the approach procedure. Why?

15. - Row does your training aircraft reacts on the pitch axis when the flaps are lowered?

16. - When the flaps are lowered, the speed tends to decrease. Why?

17. - What does the lower limit of the white arc on the airspeed indicator-represent? And its upper limit?

18. - What does the upper limit of the green arc on the airspeed indicator represent ? And its lower limit?

19. - What does the yellow arc on the airspeed indicator represent?

20. - What does the red mark on the airspeed indicator represent?

21. - (POH) On your training aircraft, is it allowed to extend partial flaps at an airspeed above the upper white arc limit and, if so, at which airspeed?

22. - Explain the operating principle of trailing edge flaps.

23. - Explain the operating principle of slots.

24. - Explain the operating principle of slats. What is the advantage of slats, as compared to the simple slots system?

25. - What do you understand by:

- Vso ___________________________________________________________

- Vs ___________________________________________________________

- VLa ___________________________________________________________

- VLe ___________________________________________________________

- Vfe ___________________________________________________________

- Vno ___________________________________________________________

- Vne ___________________________________________________________

26. - (POH) State the following airspeed values for your training aircraft:

- Vso ____

- Vs (clean configuration) ____

- VLo extension ____; retraction ____

- Vfe partial extension to ____° is ____ full extension ____

- Vno ____

- Vne ____

27. - What is the cause of pre-stall buffeting?

28. - Assuming that the aircraft stalls at low speed, the most effective way to immediately regain control is: a) to apply rudder against the dropping wing, b) to move the stick forward, c) to increase power.

29. - (POH) Considering your training aircraft, there is: a) no stall warning, b) an electrically activated stall warning, c) a pneumatically activated stall warning.

30. - As seen from the cabin, the propeller on your training aircraft rotates: a) clockwise, b) anti-clockwise.

31. - State the four propeller effects.

32. - Considering the rotational direction of the propeller and its various effects, your training aircraft will tend to yaw to the ______ at low speed and high angle of attack.

STUDY PILOT NOTE II: "THE AIRCRAFT PROPELLER AND ITS EFFECTS" AND ANSWER TRE ASSOCIATED QUESTIONARY (you may disregard for the time the theory and questions regarding the variable pitch and constant speed propellers if your aircraft is fitted with a fixed pitch propeller) .

A. - BRIEFING (01,00 h. - Total 09,00 h.)

1. - CLIMB

Altitude can be gained in three different ways, either at best rate of climb, at best angle of climb, or using the so-called en route climb procedure, also referred to as cruise climb.

Best rate of climb

The best rate of climb is associated to a specific airspeed, known as Vy, in combination with the engine's climb power setting. Note that for light trainers, climb power usually corresponds to full throttle. However, on aircraft types fitted with considerably more powerful engines, the throttle setting must be slightly reduced to what is known as METO power, i.e. "Maximum Except Takeoff", also known as "maximum continuous power". Refer to your POH in this concern.

Anyway, the combination of Vy with the recommended climb power setting results in the highest possible rate of climb. In other words, assuming that you want to gain altitude as fast as possible, you should apply climb power and increase the pitch attitude so that the airspeed indicator (ASI) reads Vy, i.e. the best rate of climb speed. Under these circumstances, the vertical speed indicator (VSI) will read the highest possible "UP" value.

Best angle of climb

Climb power can also be associated to another airspeed, slightly lower than Vy, and referred to as Vx. Vx gives way to the best angle of climb: in this case the airspeed is not only lower as a result of the necessarily aircraft's higher nose attitude, but the rate of climb is slightly lower as well. The use of the best angle of climb speed is usually restricted to the takeoff phase, immediately after liftoff, and only whenever nearby obstacles, such as trees, buildings, hills, etc. are located in the prolongation of the runway.

The idea behind the best angle of climb procedure is that, despite the somewhat lower rate of climb, the time span to reach the obstacles is longer because of the reduced airspeed: compared to the use of best rate of climb, this increased time span, in combination with the reduced rate of climb, ultimately results in a higher and safer clearance over the obstacles. A little example to substantiate this statement:

- Let us assume that best rate of climb is 1000 ft/min and that is obtained at an airspeed of 80 kts. Let us also assume that best angle of climb is 800 ft/min and that it is obtained at 60 kts. Let us finally assume that an obstacle with an elevation of 100 ft (±31 m) is located at 0,3 nms (±556 m) in the runway centreline:

a) If we use 80 kts for best rate of climb, the distance of 0,3 nms will be covered in 0,225 minutes 0,225 minutes at 1000 ft/min gives way to a height of 225 ft when passing the obstacle, i.e. a margin of 125 feet;

b) If we use 60 kts for best angle of climb, the distance of 0,3 nms will be covered in 0,3 minutes 0,3 minutes at 800 ft/min gives way to a height of 240 feet when passing the obstacle, instead of the previous 125 feet, thus a margin of 140 feet.

Quod erat demonstrandum !

But perhaps one may wonder about he fact that, when climbing at Vx, and notwithstanding that the nose attitude is higher with the same climb power, the rate of climb is less. Read PILOT NOTE III: "CLIMB AND DESCENT", and you will learn that only one single airspeed is able to produce the maximum rate of climb: any deviation, either more or less, results in a lower rate of climb value.

On elementary trainers, the speed difference between best rate of climb and best angle of climb is very small, to the point of seeming rather academic, although in some cases Vx is indeed required. However, on fast high performance aircraft, and particularly on jets, this difference becomes very significant and often is a very serious safety factor.

Enroute climb

Climbing in a sustained way at Vx, and even at Vy, might give way to somewhat high engine temperatures, oil and CHT, but as long as these remain within limits, no harm is done. But, because of the fairly high nose attitude, you will notice that the forward outside view may be considerably impaired, which is detrimental to safety. In the POH, besides the specific values for Vy and Vx, you will find the recommended airspeed for enroute climb. This speed is higher than Vy and, although it implies a lower rate of climb, it ensures a much better engine cooling as well as a better forward view. It should be used any time that neither Vx or Vy are required, and is thus the most usual climbing speed.

Let us come back a moment to the climb power principle: as said earlier, on light aircraft it often corresponds to full power. Nonetheless, many pilots have the tendency to reduce the power setting somewhat shortly after takeoff, while maintaining either Vx or Vy, claiming that this power reduction is favourable for the engine's life. This is an acceptable point of view, provided that the airspeed is first increased to enroute climb: if this is not taken care of, and if no specific instructions are provided by the POH on that account, their reasoning is completely erroneous ! Indeed, unless otherwise recommended, fact is that at full power some extra amount of fuel is sent to the cylinders... and it is precisely this additional fuel which contributes to the engine cooling. In other words, far from being ”good for the engine", reducing power when not required to do so, and before having increased the airspeed, is much more likely to cause premature engine wear. Note that on most elementary trainers, engine overheat is only discernible by checking the oil temperature indicator. See PILOT NOTE I for further explanations.

Many pilots also believe that the lift Fz is greater than the weight during climb. This is untrue, and in fact the lift is even smaller than the weight:, climb performances depend on the engine power available and are by no means related to lift. This is further discussed in PILOT NOTE III.

Some people wonder whether the climb performances would not improve with a small deflection of the flaps, as indeed this provides considerably more lift capability. Again, lift plays no part, but the additional drag, whichever small, does: it must be overcome by the power available and, considering that the maximum power is already selected, the climb performance must inevitably decay. True, flaps are sometimes used for the takeoff but, as we will discuss later, this is only to shorten the takeoff run, not to increase the climb performance once the aircraft is airborne. Again, all these matters are discussed in PILOT NOTE III.

Practical execution of the climb

a) Transition to climb

During the takeoff phase, the transition to climb is of course initiated "automatically" immediately after becoming airborne; obviously, it can as well be carried out departing from straight & level flight, from descending flight, during turns, etc., Remember that to obtain maximum power the carburettor heating system should be selected to COLD. Furthermore, and at least at lower altitudes, a rich fuel/air mixture is necessary. In other words, the mixture control must be selected to RICH (for the time being you use the mixture control solely to start or to stop the engine: its further use will be covered later and is fully explained in PILOT NOTE I).

Assuming a transition from cruise to climb, the first step is to increase the thrust to climb power, and simultaneously raise the aircraft's nose in the adequate attitude to obtain Vx, Vy or en route climb: these are three slightly different pitch attitudes which you should be able to distinguish fairly well from each other in order to select anyone of them by using either external references or the attitude indicator. At this stage, using external references is essential, the purpose of the attitude indicator being mainly to crosscheck. When transitioning from straight & level flight to climb, you should further pay attention to the following:

1°) The increasing power setting combined with the couple between thrust and causes the nose to drag already pitch up on its own: because of this, and to avoid overcontrol, the action on the elevator should be cautious;

2°) The throttle lever should be advanced to full power firmly, but not abruptly. On engines fitted with a fixed pitch propeller, opening the throttle too enthusiastically can easily give way to momentarily, but nonetheless harmfully, exceeding the maximum allowable RPM. This is also the case when you advance the throttle to full power, but that you loiter too long before raising the aircraft's nose;

3°) Be aware that abrupt use of the throttle sharpens the yaw due to the propeller effects.

Once the correct pitch attitude is reached, the ASI reading will stabilize at the required value. Adjust the trim so that the aircraft flies "hands off".

Think about the propeller effects during climb: keep the ball centered and the wings level to maintain the heading unchanged.

For climb, as well as for level flight, you must be able to maintain the speed within 10 kts and the heading within 10°. Remember that these are maximum allowable deviations which must be corrected back to the "target" value.

Be also aware that, although the carburettor heating system must normally be selected to COLD during climb, and that the chances for carburettor icing at full power are remote, such icing is not completely excluded. Consequently, if necessary, don't hesitate to re-select full HOT: the airspeed will decrease so that you will need to lower the aircraft's nose somewhat to regain the target speed, and the rate of climb will decrease somewhat.

b) Transition from climb to level flight

Act as follows:

- Begin gradually lowering the aircraft's nose to the adequate attitude a few feet before reaching the required altitude (some 20 to 50 feet before, depending on the rate of climb) ;

- Maintain climb power until the ASI reads the required cruising speed before reducing to the cruise setting. But here again, be cautious with a fixed pitch propeller: ensure that the maximum RPM is not exceeded;

- Be aware that the rudder input due to the propeller effects is no longer needed (unless you would maintain a slow cruising speed);

- Normally, the mixture control should now be adjusted, as explained in PILOT NOTE I. However, at this stage of the training it may be left in RICH position.

c) Climbing turns

Climbing turns are carried out in exactly the same fashion as in normal level flight, except for the nose attitude which, of course, is significantly higher. Furthermore, the rate of climb tends to decay because of the increased load factor: this is why climbing turns should always be shallow, with a maximum bank angle of 15°.

As climbing turns are carried out at a lower speed in combination with high power, the propeller effects are very marked and, as was the case for level turns at low speed, the rudder inputs to keep the ball centered are significantly different for a left climbing turn as compared to a right one.

Finally, it should be noted that during climbing turns, there is a much stronger tendency for the bank angle to increase as compared to level turns. This phenomenon is fully explained in PILOT NOTE III.

2. - DESCENT

The descent can be carried out with or without engine power. The latter case is the so-called glide descent (glijvlucht/vol plané) which, at least on propeller driven aircraft, has more to do with an emergency situation in case of an engine failure than with normal operations. Indeed, prolonged glides are never to be recommended, firstly because the engine undergoes a severe and harmful cooling process, secondly and as a result of this cooling, because the engine might falter when power is subsequently increased.

Practical execution of the normal descent

Before initiating the descent you must ensure that the mixture control lever is set to RICH, or at least move it towards a richer fuel/air combination. However, as said earlier in relation to climbing, at this stage the use of the mixture control is restricted to starting the engine or shutting it down after the flight. Its airborne use will be fully covered later. Regarding the carburettor heating, it may be left to the appreciation of the pilot when only partial power reduction is intended for a normal descent. However, if a glide descent is considered. the carburetor heating MUST previously be selected to HOT at all times.

Another aspect of the descent concerns the well-being of your passengers (and possibly of yourself). Indeed, at high rates of descent many people experience considerable discomfort due to the increasing air pressure on the ear-drums (trommelvlies/tympans), and the resulting pressure unbalance in the inner ear may give way to a very painful feeling. This can be prevented by swallowing, yawning, or blocking the nostrils while blowing in the nose, but persons suffering a cold in the head or any kind of inflammation in the nose of in the ears will usually be affected anyway. Another way to reduce these effects is to limit the rate of descent at 500 ft/min which is the standard procedure for any non-pressurized aircraft. Obviously, to maintain such a specific value; the presence of a VSI is necessary; if thus is not, the case, all you can do is to limit the descent rate by approximation.

Anyway.... assuming, that a VSI is available, it is not difficult to loose altitude at ±500 ft/min in combination with whichever airspeed by modulating the pitch attitude and the engine power.

Three examples:

1˚) You may decide to descent at 500 ft/min at an airspeed in excess of normal cruise value. To this purpose, simply lower the nose until the required vertical rate is obtained: the forward pressure on the stick should be carried out cautiously, keeping, in mind chat; moat VSI’s lag somewhat before reading the actual value. The airspeed builds up as a result and, once the required value is attained, the power should be reduce as needed to maintain it. The elevator trim should then be adjusted to ensure "hands off” descent.

When using this method, care should be taken not to exceed the green arc if the weather conditions are choppy. If an airspeed reduction becomes necessary", simply reduce power somewhat, and re-adjust the pitch attitude to keep the rate of descent. unchanged.

2˚) You may decide to descent at 500 ft/min while maintaining the current cruising speed: the only difference with the first choice is to lower the nose and to reduce power simultaneously.

3˚) Assuming that you wish to descent at 500 ft/min but at a lower airspeed than the current cruise value, you should first reduce power (possibly even to idle so as to reach the required speed as quickly as possible). Knowing that a power reduction gives way to a pitch down, you should prevent this motion by exerting a gradual back pressure on the stick in order to hold the nose up until the required speed value is reached. Only at this moment the nose should be lowered to pick up the required rate of descent while adjusting power to maintain the required airspeed. The aircraft should then be trimmed as necessary. If the airspeed needs to be increased, simply add some power and re-adjust the pitch attitude to maintain the rate.

Agreed, these three methods seem to be more relevant to plain instrument flying than to normal basic operations. However, it must be remembered that at this stage the use of the instruments is of secondary importance and should be restricted to a quick glance as indeed, let us emphasis it once more, the need for look-out remains paramount. Consequently, the degree of accuracy might be a little less, but with some training you will soon be able to handle these descent procedures fairly well.

Practical execution of the glide

During a descent at idle power, the situation is somewhat different. For one thing, there is no thrust available to adjust the airspeed which, in this case, can only be modulated by acting on the elevator: the lower the nose, the higher the speed and the higher the rate of descent, and vice-versa.

The question now is which airspeed should be chosen! The answer to this is to be found in the POH under a variety of headings such as "best gliding speed", "maximum glide", "recommended power off gliding speed", or other similar names. All these denominations imply one and the same principle: the reported airspeed corresponds to the angle of attack which provides the best lift to drag ratio (Fz/Fx), i.e. the angle of attack whereby the maximum lift is obtained for the minimum drag. Only one single angle of attack provides this maximum ratio which, in turn, ensures the smallest glide angle, thus allowing the aircraft to glide over the longest distance (see PILOT NOTE III).

Note that the aircraft's weight has no influence on the gliding distance, PROVIDED THAT THE BEST LIFT/DRAG ANGLE OF ATTACK IS MAINTAINED. Nonetheless, the POH of many aircraft, for instance of the Cessna l72RG, anna 1980, recommends the following best glide speeds:

- for 2650 lbs, 73 KlAS

- for 2250 lbs, 67 KlAS

- for 1850 lbs, 61 KlAS

So, why then these three different gliding speeds for three different weights? Let us consider the lightest case: the best gliding speed being 61 KlAS for 1850 lbs. Let us assume now that, for a weight of 2650 lbs, we would STILL maintain 61 KlAS: this would imply 'that, in order to carry the higher weight over a certain distance, the angle of attack would have to be increased, thus deviating from the best lift/drag ratio, consequently steepening the glide angle, and decreasing the gliding distance. By increasing the speed to 73 kts the angle of attack for best lift/drag ratio is automatically maintained. If, on the other hand, a speed of 73 KlAS would be used for a weight of 1850 lbs, the angle of attack would have to be decreased, thus again deviating from the best lift/drag ratio, thus also steepening the glide angle and decreasing the gliding distance. In fact, gliding at 61 KlAS for 1850 lbs, at 67 KlAS for 2250 lbs, or at 73 KlAS for 2650 lbs, always results in the same angle of attack, and in the same gliding distance. On lighter aircraft, only one best gliding speed is reported: this is simply because the possible weight variations are too small to significantly affect the resulting gliding distance.

Note: It is obvious that the wind plays a major part in the gliding distance: any aircraft will glide farther with tailwind than with headwind, but the heavier it is, the more distance it will cover, both with headwind and with tailwind, because of the higher groundspeed resulting from the increased gliding speed. This is the reason why gliders use sometimes additional ballast when the purpose of the flight is to cover the maximum possible distance.

Transition from level flight to glide

- DO NOT FORGET TO SELECT THE CARBURETOR HEATING SYSTEM TO "HOT" PRIOR TO INITIATE THE POWER REDUCTION TO IDLE: this is of paramount importance because carburettor icing is most likely to occur when the engine runs at idle. Nonetheless, and particularly under cold weather conditions, it must also be kept in mind that the carburettor heating system itself is likely to become impaired because of the severe engine cooling during prolonged glide descents, which might lead to engine stoppage as well. Therefore, DURING EXERCICES INVOLVING LONG GLIDES. THE ENGINE POWER SHOULD BE INCREASED MOMENTARLY. ABOUT EVERY 30 SECONDS.

- Remember that when the throttle lever is reduced to idle power, the nose pitches down immediately. As said earlier, this must be prevented by smooth back pressure on the stick to keep the nose up until the gliding speed is reached. In other words, maintain the altitude until this speed is obtained. At that moment, gently relax the back pressure to let the nose drop from itself until it reaches the adequate pitch attitude, maintain this attitude and trim the aircraft accordingly. The approximate pitch attitude in relation to the ground, as well as the associated position of the model aircraft on the attitude indicator, should be committed to memory. This requirement relates to the engine failure situations which will be discussed later.

- The throttle lever should be reduced firmly to idle, but not abruptly. Abrupt use of the throttle lever is never good for the power plant and, in addition, it sharply increases the propeller effects which, by the way, are reversed during the descent: assuming that the aircraft tends to yaw to the left during climb, it will tend to yaw to the right during descent, and vice versa. For the remainder, just as for climb, keep the ball centered at all times, and keep the wings level!

Transition from normal descent or glide to level flight

The nose must be moved up to the required level attitude in due time, say about 50 feet before reaching the prescribed altitude, particularly when gliding is involved. The engine power should be increased simultaneously. Next actions are to be carried out in the following order:

- select the carburettor heat to COLD;

- re-adjust the power setting;

- re-adjust the trim;

- re-adjust the mixture control.

Descending turns

Just as was the case for climbing turns, descending turns are carried in the same fashion as during level flight, except of course for the pitch attitude and the fact that, here again, you will notice a significant difference in rudder input far a right descending turn as compared to a left one: this is particularly true during glide descents.

Note that for descending turns there is no bank angle limitation such as in climb. Another fact that you might notice is that during descending turns the bank angle tends to decrease whereas, for climbing turns, it tends to increase (see PILOT NOTE III) .

To conclude this lesson, a few words about how increase the rate of descent without increasing the airspeed. To this purpose, the most usual way is to use the flaps, as their extension goes, along with an increase of lift, but also an increase of drag resulting in an airspeed decay which can be prevented by lowering the nose, thus increasing in fact the angle of descent. As no power at all is used in a glide descent, lowering the nose is the only way to keep the airspeed under control. The full extension of the flaps produces a very strong drag, thus a significant tendency for the airspeed to fall off. In other words this increased drag allows to lower the nose very steeply, thus to obtain a much higher rate of descent without the airspeed building up. As we shall see later, this is extremely useful for landing.

Some light aircraft are fitted with so-called speedbrakes, also referred to as spoilers (remkleppen/ aérofreins) . These axe surfaces which are usually located above and/or under the wings, sometimes somewhere on the fuselage, and which can be extended or retracted at will by the pilot. Most gliders are fitted with such a system, and so are most heavy jet aircraft. When retracted, these surfaces either disappear in the aircraft's structure or become flush with it, thus leaving the wings (or fuselage) absolutely "clean". The major difference with flaps is that speedbrakes may be extended or retracted without increasing or decreasing the lift: they only affect the drag, thus the airspeed which can be controlled by varying the nose attitude. In other words, they allow the pilot to modulate the angle of descent as needed without any concern about associated lift changes. Also this will be discussed with the landing procedures.

Finally, some elementary trainers have neither flaps, nor speedbrakes, in which case the so-called side-slip procedure is used to increase the rate of descent. Also this will be discussed in due time.

B. - FLIGHT TRAINING (Dual 01,00 h.- Total 06,00 h.)

In order to clearly demonstrate the difference between Vx and Vy, fairly calm weather conditions are needed. This implies that the prevailing surface winds must be light or, if not, that a climb to somewhat higher altitudes will be needed to encounter adequate conditions . . . . . , but this again might be prevented by the cloud base or by local ATC restrictions. At any rate, assuming that this demonstration turns out to be unsatisfactory for whichever reason, it will be repeated at first opportunity. At any rate, this demonstration requires the availability of a VSI.

It should be noted that climbing at higher altitudes involves additional "complications", particularly with regard to the best rate and best angle of climb speeds. Indeed, besides the need for a properly adjusted mixture control, the corresponding values mentioned in the POH are valid at sea level only. As is explained in the groundcourse, fact is that the ASI is an air pressure instrument measuring the difference between dynamic and static pressure: this implies that it shows the correct airspeed only at sea level (and even so, only under standard (ISA) conditions). At higher altitudes, there is a difference between the indicated airspeed (lAS) and the true airspeed (TAS), the lAS being lower than the TAS. This is one of the major items which is discussed in the navigation theory. But it also plays its part when considering the best rate of climb and best angle of climb speeds. Indeed, as the altitude increases, these values must be decreased. Most Cessna handbooks mention the required best rate of climb speed from sea level upward: for instance, the Cessna 152, anna 1979, mentions an IAS of 67 KlAS (Knots Indicated Air Speed) at sea level against 60 KlAS at 12000 ft. This means an average decrease of one knot per 2000 feet which can be taken into consideration for any other type of aircraft. The various aspects of high altitude operations will be covered in lesson 32.

Depending on the prevailing turbulence conditions, the difference between Vx and Vy will be demonstrated by the instructor immediately after takeoff, or at any other suitable moment in flight. He will take over the controls, stabilize the airspeed at best angle of climb value, adjust the trim, and maintain the aircraft in the required pitch attitude so as to allow you to notice:

a) the rather high nose up attitude both in relation to the ground and on the attitude indicator; try to memorize these two positions;

b) the resulting rate of climb on the VSl;

c) the ball properly centered and the wings level.

He will then draw your attention to the ball in particular and notify you that he will release the pressure on the rudder: notice the ball moving off center due to the propeller effects, the resulting yaw motion and ensuing bank angle.

He will then lower the nose somewhat to adjust the airspeed at best rate of climb value, re-adjust the trim, and maintain this new pitch attitude. Notice, and again try to memorize, this new attitude as previously. Notice in particular the increased rate of climb on the VSI despite the somewhat lower nose attitude. Of course, the ball must till be kept centered with the rudder.

Assuming that the aircraft is fitted with flaps, the instructor will the draw your attention to the fact that he will now momentarily extend them to the recommended takeoff position: observe the reducing rate of climb notwithstanding that best rate of climb speed is maintained.

Finally, he will lower the nose further to obtain cruise climb, re-trim, and give you time to memorize this third attitude, noticing the resulting rate of climb which will be obviously lower, and possibly the decreasing engine temperatures.

The instructor will then level off at a specified altitude, put the aircraft in level flight at normal cruise speed, and subsequently demonstrate how to descend with idle power at the published best gliding speed. Notice:

a) the previous selection of the carburettor heating system to HOT;

b) the gradual reduction to idle power while the nose is prevented to pitch down by adequate back pressure on the elevator, if so wished, the elevator trim may already be rotated towards "nose up" while the airspeed decays;

c) the smooth way in which the required pitch attitude is picked up upon reaching the required gliding speed and the fine tuning of the elevator trim; notice in particular f and memorize, this position of the nose in relation to external references as well as on the attitude indicator;

d) the resulting rate of descent on the VSI;

e) the ball properly centered and the wings level.

As he did for climb, the instructor will draw your attention to the ball and notify that he will release the rudder pressure: notice again the ball moving off center due to the propeller effects, but; in reverse direction as compared to climb, the resulting bank angle and the ensuing yaw motion.

Assuming that the aircraft is fitted with flaps, the instructor will then notify you that he will momentarily select them to full down position. Notice the following:

a) the significant tendency for the airspeed to decay, and the required additional pitch down to maintain it;

b) the resulting rate of descent on the VSI;

c) the further elevator trimming.

On the other hand, assuming that the aircraft is fitted with speedbrakes f he will alternatively extend then retract them. Always keep in mind that flaps extension increases BOTH lift and drag. whereas speedbrakes extension increases DRAG ONLY: the latter may thus be retracted without any potentially dangerous loss of lift!!! In other words, and this is of vital importance during a final approach for landing, whereas speedbrakes may be extended or retracted at will, flaps are normally not to be retracted until after the aircraft is firmly on the ground (or following a go-around) .

The instructor will now re-establish the aircraft in a normal glide descent with flaps or speedbrakes again retracted and level off the aircraft at a specified altitude.

After these rather lengthy demonstrations, the remainder of the time available will be yours, putting alternatively the aircraft in climb at Vx, Vy or cruise climb, levelling off at specified altitudes then, after a transition to level flight at normal cruise, exercising descents with or without power, the whole combined with climbing and descending turns. Conditions permitting the last descent to circuit altitude will be carried out at

high speed, with power on, and at a rate of ±500 ft/min.

The instructor will "nurse" you in the traffic circuit at usual, and again you will try to put the aircraft on the runway yourself to the best of your abilities.

Don't worry if your performances are wavering somewhat and that the instructor constantly needs to call for this or that correction. This is absolutely normal, unless you are one of the few "born with a stick in their stomach". The important thing at this stage is to know what you are trying to do: doing it correctly will come very soon.

C. – QUESTIONARY (You can print the PDF file at the begining of this lesson to answer the questions in writing, than correct it with your instructor)   

01. - Explain the difference between best rate of climb and best angle of climb.

02. - The symbol Vx stands for ___________________________; the symbol Vy stands for ________________________

03. - (POH) For your training aircraft, Vx = _____ kts 

                                                     Vy = _____ kts

04. - State the major reason why neither Vx nor Vy should be maintained too long.

05. - The VSI will show the highest rate of climb when using: a) Vx, b) Vy

06. - (POH) State the recommended cruise climb speed for your training aircraft. State two advantages of climbing at this speed as compared to Vy.

07. - Under which circumstances would you use Vx?

08. - (POH) On your training aircraft, the value of maximum continuous power corresponds to the full open throttle setting. True or false?

09. - (POH) Assuming that your answer to question 08 is "false", state the power setting which is to be used. Alternatively, state the recommended power setting for cruise climb

10. - You wish to climb at best rate of climb. Assuming that the POH claims that full power should be used, it is still advisable to reduce the throttle setting somewhat to spare the engine. True or false?

11. - METO power stands for ____________________________ power

12. - During climb, the lift is: a) the same as during level flight, b) less than in level flight, c) more than in level flight.

13. - The climb performances depend on: a) the excess lift, b} the excess power, c) a and b.

14. - When the flaps are partially extended they improve the lift to a considerable extend still, they cause a decay in rate of climb. Why?

15. - During climb, the carburetor heating should normally be selected to "COLD". Why?

16. - Carburetor icing cannot occur when the engine is set to climb power. True or false?

17. - You increase the power setting during level flight to initiate the climb. The aircraft tends to pitch up by itself. Why?

18. - On your training aircraft, the propeller effects cause a yaw to the _____ during takeoff and climb, and to the _____ during descent.

19. - Climbing turns should be carried out with a maximum bank angle of _____? Why?

20. - During climbing turns, the aircraft shows a tendency to: a) increase its bank angle, b) decrease its bank angle, c) neither a nor b.

21. - Prolonged gliding exercises with the engine at full idle power are to be avoided. Why?

22. - State your very first action before reducing the throttle to full idle in order to initiate a descent.

23. - Normal descents should be carried out at a reduced rate of about 500 ft/min. Why?

24. - You are flying level at 120 kts. Assuming the presence of a VSI, you wish to descend at 500 ft/min. How do you achieve this, considering a descent target airspeed of: a) 140 kts, b) 120 kts, c) 100 kts.

25. - (POH) The best gliding speed at maximum takeoff weight for your training aircraft is ______ kts. State the advantage of using this speed.

26. - Assuming no wind, the weight has no influence on the gliding distance provided that _____________________________________________

27. - Assuming the presence of wind, a weight increase causes the gliding distance: a) to increase with headwind, b) to increase with tailwind, c) has no effect, d) a and b.

28. - You selected the carburettor heating to HOT prior to start a glide descent exercise. Doing so ensures that no carburettor icing will occur. True or false?

29. - During a glide descent, you select partial flaps to increase the lift. By doing so you decrease the angle of descent. True or false?

30. - Assuming that your aircraft is fitted with speedbrakes, extending them causes the angle of descent to increase. True or false?

31. - State the major aerodynamic difference between flaps and speedbrakes.

A. - BRIEFING (01,00 h. - Total 10,00 h.)

I. - Use of the magnetic compass

The theory related to the magnetic compass (magnetisch compas/compas, magnétique) is extensively covered in the navigation groundcourse. This lesson concerns mainly the practical use of this instrument regarding the way to pick up and maintain specified headings.

To put it simply, the magnetic compass is composed of a magnetized needle which remains steadily oriented towards the (magnetic) North. The needle is connected to a card, divided in 360 degrees, around which the aircraft rotates during direction changes. Note that in most aircraft magnetic compasses, the needle is in fact an annular magnet, as illustrated in figure 1.

Magnetic compasses are rather unstable: because of this, and in order to dampen all kind of oscillations, the complete mechanism is located in an airtight casing, completely, filled with a liquid, usually acid-free kerosene, which, besides damping, also ensures that no friction impairs the operation of the instrument. Before departure, it is important to verify that no leak has occurred: such a, leak is indicated by the presence of a visible liquid level, by air bubbles, and/or by the fact that the graduations of the card are discoloured. Furthermore, the magnetic compass card should be checked for full freedom during taxi, as shown by the headings varying as expected when turning. Finally, and this requirement is essential for navigation flights, the magnetic compass must be accompanied by an adjacent deviation card which must carry the date of the latest "compass swing", i.e. a procedure which should be carried out on the ground by an approved specialist at more or less regular intervals, some sources recommend every three months to ensure that compass deviations are kept as small as possible (see also PN VII: "MAGNETIC COMPASS”).

Be, aware that, besides aluminium material which is non-magnetic, no metal objects or items such as headsets or microphones are to be placed in the immediate vicinity of the magnetic compass failing this precaution would inevitably give way to completely erroneous readings .

We also take this opportunity to discard the very common belief that the needle, or annular magnet, which is influenced by both the horizontal and vertical components of the Earths’s magnetic field, would be fitted with some kind of counterweight to eliminate the effects of the vertical component the so-called dip. It is indeed correct that the dip tendency is taken care of, and that the needle remains horizontal despite the existence of the vertical component, but the theory about the use of a counterweight is completely false. The only reason why the needle remains horizontal is simply that the pivot point (ophangingspunt/point de suspension) of the magnet system is located above its center of gravity so that, any time a tendency to dip occurs, a levelling couple is created between the upward force acting on the pivot point and the downward force acting on the center of gravity (fig. 2).

As will be learnt during the groundcourse, the compass needle shows the direction of the so-called magnetic North, rather than the geographic North: this difference is known as the variation. However, the compass needle is subject to various errors, amongst which the so-called deviations due to metal parts and electric circuits within the aircraft structure. Besides the deviations, whose values vary with the aircraft's heading (and which are reported on the associated deviation card), other errors exist, namely the so-called turning errors which are due to the aircraft's bank angle, as well as errors due to airspeed variations, i.e. acceleration and deceleration errors: it are these two sorts of error types which we will discuss in this lesson.

Without going into the details, let us simply state that it is the vertical component of the Earth's magnetic field which is the cause of turning errors and airspeed variations errors. Some idea of what in fact is happening is provided by figure 3:

a) When the aircraft is banked, as it is the case during turns, the levelling couple, mentioned here above with regard to the dip, cannot act any longer, and the needle will orient itself in accordance with the vertical component;

b) Accelerations and decelerations cause the needle to tilt due to inertia so that, also in this case, the needle tends to follow the vertical component.

These phenomena lead to the following conclusions:

a) Turning errors

These errors are maximum when the aircraft approaches heading North or South, respectively 000° or 180°. They are non­existent on headings East or West, respectively 090° or 270°, because in this latter case the dip levelling couple remains fully effective. The amplitude of turning errors increases as the bank angle is increased. Consequently, whenever a heading is to be taken by means of the magnetic compass, a first requirement is to restrict the bank angle to a maximum of 30°, and preferably to keep it between 15° and 20°. Furthermore, for all practical purposes, whenever one wishes to steer a "northerly" heading, the turn should be stopped before the required heading is reached; when turning towards a "southerly" heading, the turn should be continued until after the required heading has been passed. However, in order to pick up heading 090° or 270°, no correction is required and the turn should be stopped exactly upon reaching these values.

In fact, the corrections to be applied gradually increase from a zero value on headings 090° and 270°, to a maximum value of about 30° before reaching heading 000° or after reaching heading 180°. A few examples:

- To pick up heading 000° (or 360°, which is the same); the turn should be rolled out about 30° before reaching the heading, i.e. at the moment that the compass shows 030° for a turn to the left, or 330° for a turn to the right;

- To pick up heading 180°, the turn should be rolled out about 30° after the heading has been passed, i.e. at the moment that the compass shows 150° for a turn to the left, or 210° for a turn to the right;

- To pick up heading 090° or 270°, the turn should be rolled out at the moment that the compass shows the required value. In fact the wings must reach level attitude at that very moment, which means that some lead is to be taken into account: indeed, 'if the bank angle should be maintained until the compass actually shows either 090° or 270°, the time to roll out would put the aircraft on a heading of some 095° or 275°. It is thus advisable to consider a lead of about 5° to start the roll out manoeuvre;

- To pick up an intermediate heading, the correction should be proportionally decreased. For instance assuming that heading 045° is required: this is halfway between 000° and 090° and the maximum correction of 30° should be reduced by half, thus a correction of 15° (in this specific case: before reaching heading 045°) should be considered; for a required heading of 070°, about 7° correction before; for a required heading of 135° (halfway between 090° and 180°), about 15° after passing the heading, etc.

The values of the corrections mentioned here above are valid for bank angles of about 30° If the bank angle is considerably smaller, say 15°, they can be about halved. At any rate, be aware that all these values are approximations (in fact, they vary with the latitude: be aware that turning errors will not occur at the (magnetic) Equator (because there is no dip) . . . . . and that they are reversed in the Southern Hemisphere).

In any case, after roll out, the wings should be kept absolutely level until the compass stabilizes, then some "fine tuning" should be applied if necessary. A common way to remember the sense of the correction is the mnemonic: "NEVER SEE NORTH, ALWAYS SEE SOUTH".

b) Acceleration and deceleration errors

The amplitude of these errors is maximum when the aircraft is flying due East or West, i.e. on headings 090° or 270°. They are non-existent on headings 000° and 180°, again because the levelling couple is fully effective in this case. Consequently, be aware of the following:

- When the aircraft travels on the East-West axis and that the airspeed increases, the compass heading deviates to the North despite the fact that the flight direction remains unchanged; on the other hand, if the airspeed decreases, the compass heading deviates to the South. Also here a mnemonic is available, namely "ANDS" (acceleration North/deceleration South).

- The amplitude of these deviations increases with the strength of the accelerations and decelerations; The amplitude of these deviations also varies according to the heading flown and, as said, becomes zero when the aircraft travels on the North-South axis;

- The influence of accelerations and decelerations is only momentary: once the airspeed stabilizes at either a higher or lower value, the magnetic compass will revert by itself to the original heading. Consequently, these deviations are to be disregarded;

- Accelerations and decelerations can be produced in different ways, for instance by increasing or decreasing the engine power, or by raising or lowering the aircraft's nose. They can also be produced by turbulent conditions, in which case the magnetic compass can become particularly unstable: under such conditions it is more than ever necessary to use external references (unless a directional gyro is available) without "chasing the compass" in order to keep the actual heading unchanged.

- As was mentioned for the turning errors, the amplitude of the acceleration and deceleration errors varies with latitude: again, at the (magnetic) Equator no such errors can occur . . . . . and become reversed in the Southern Hemisphere.

II. - The directional gyro

It appears from the previous theory that the use of the magnetic compass is not free from a few drawbacks. Therefore, and although it may be missing on some elementary trainers, a directional gyro, or D.G. for short, is often part of the aircraft's instruments.

The D. G. is a heading indicator which is much easier to use because it remains absolutely stable and that it is not subject to the magnetic compass's turning and acceleration/deceleration errors. It is a gyroscopic instrument whose operation is fully explained in the groundcourse (see also PILOT NOTE II which discusses the propeller's gyroscopic effects and the phenomena of rigidity and precession which are common to all gyroscopes). On the practical side, you must at least be aware of the following particularities:

a) The D.G. has no directional properties at all, unless it is previously set in accordance with the heading shown by the magnetic compass. This is done before initiating the taxi, shortly after starting the engine, once the built-in gyroscope has reached its operating rotation speed through action of the engine driven vacuum pump, by means of the associated "RESET" knob.

b) Although it is not affected by turning, acceleration and deceleration errors as is the magnetic compass, the D.G. is not entirely free from any inconveniences and, once it has been set in accordance with the magnetic compass, its indications are likely to vary somewhat because of two other types of errors known as apparent drift and real drift:

- The apparent drift is a direct result of the gyroscopic rigidity (see PILOT NOTE II). Indeed, although the gyroscope maintains its position, the Earth itself rotates around its axis at a rate of 360° per 24 hours (or 15° each hour). Therefore, assuming that a constant D.G. heading is maintained, and despite the fact (we would nearly say "because of the fact") that the D.G. works absolutely perfectly, a discrepancy might occur after some time between the magnetic compass heading and the D.G.'s. As will be explained in the groundcourse, the apparent drift, which is very small anyway, is almost completely eliminated by means of a device fitted in the instrument, and causing the gyroscope to process in accordance with the Earth's rotation rate.

- Whereas the apparent drift may be disregarded for all practical purposes, real drift errors are less harmless. These may be due to possible minor imperfections within the instrument. Although they may very well occur in straight & level flight, real drift errors are more likely to show during turns because of the almost inevitable friction between the internal gimbal rings (cardanringen/cardans), giving way to the so-called gimbal error. The ever present possibility of real drift errors requires the D.G. to be repeatedly cross-checked with the magnetic compass heading, and to be reset accordingly if needed. Such a crosscheck is recommended about every 10 to 15 minutes during straight flight, and must be carried out after each significant heading change. However, it should be noted that such a "D.G. check" demands three conditions:

1°) the wings must be absolutely level;

2°) no significant turbulence should be prevailing;

3°) the airspeed must be steady.

Be aware that if anyone of these conditions is not fulfilled, the magnetic compass might momentarily read erroneously, and the possible D.G. drift error might be worsened by an incorrect reset. Needless to say that these precautions become essential during navigation flights when the D.G. is used as heading indicator.

The possibility for real drift errors, and particularly the gimbal error, increases as the bank angle becomes steeper. In addition, most D.G.'s are limited at ±55° of bank and pitch angle. When these angles are exceeded, the gimbals hit their stops and cause the gyroscope to topple, i.e. to process with such violence that it starts spinning uncontrollably, and that the heading card rotates in concert. This phenomenon might happen for instance during stall exercises, and will almost certainly occur when performing high performance turns (see lessons 10 and 22).

It should also be noted, even without gimbal error, any heading change is likely to give way to a discrepancy between the magnetic compass and the D.G. for the very simple reason that the magnetic compass is subjected to deviation errors whereas the D.G. is not. In other words, a significant discrepancy between both instruments does not necessarily mean that the D.G. is at fault: it might very well be due to a poorly compensated magnetic compass.

c) The D.G., as any other gyroscopic instruments, can be either pneumatically or electrically driven. As far as pneumatic operation is concerned, we mentioned already the disadvantage of the venturi system, which is why light aircraft D.G.'s are usually operated by means of an engine driven vacuum pump. At any rate, whether a venturi or a vacuum pump is used, the instrument panel must be fitted with an associated vacuum gauge which must show "in the green": if this is not the case, chances are that the gyroscope does not turn at its required rotation speed and that the instrument's operation is questionable. Note that it is not because the vacuum gauge shows correctly that the associated gyroscopic instrument (s) are necessarily operating properly: indeed, each of the pneumatically operated gyroscopic instruments is fitted with its own air filter which might become partially blocked and give way to inaccuracies.

d) In some light aircraft, the D. G. may be of the slaved type. Without going into details, this is a gyroscope which is linked to, a more suitable expression is "synchronized with", a so-called flux valve which is usually located in one of the wing tips. The flux valve detects the Earth's magnetic field and induces a resulting voltage which is used to activate the heading indicator. This system, known under a variety of denominations (distant reading compass, gyrocompass, magnesyn, gyrosyn) associates the stability of the gyroscope to the accuracy of a magnetic compass: it shows no turning, acceleration or deceleration errors, and does not need to be cross-checked with the magnetic compass which¡ although still available, acts only as a standby instrument. Incidentally, note also that, because the flux valve is always placed in a remote location (usually the wing tip), the compass deviation problems are also eliminated.

III. - Effect of wind during turns

Very soon you will be flying circuits, i. e. circling the airfield in order to train so-called touch-and-goes: this means landings immediately followed by another takeoff, another circuit / landing again, etc. During these exercises, it may happen that the ground controller requests you to perform a 360° turn in order to increase the separation between you and another aircraft. It is obvious that, if there is no wind at all and that the bank angle remains constant throughout the turn, the aircraft will fly a perfect circle which in fact is what the controller expects. However, no wind is rather a rarity, and all too often it is observed that pilots executing such a 360° turn let their aircraft hopelessly drift away as shown in fig. 4. This is certainly not without any danger when several aircraft are operating in the circuit: flight safety demands that one is able to perform a "three-sixty" while maintaining a near constant radius in relation to the ground under any wind conditions.

To achieve a perfect circled path, it is usually necessary to constantly vary the bank angle from a minimum to a maximum value, then back to a minimum, etc. One must be aware that when the aircraft is subjected to tailwind, the speed in relation to the ground is higher than with headwind: during a turn, this higher groundspeed will cause the path to be elongated if the bank angle remains unchanged. Conversely, and still assuming a constant bank angle, the path will be "compressed" as soon as the aircraft comes under the influence of headwind. The end result is that, after the completion of a number of "three-sixties", the aircraft ultimately rolls out at an entirely different location as compared to the point where the procedure was started. Consequently, in order to perform a constant radius 360° turn, you should act as follows:

1°) Upon initiating the manoeuvre, take a landmark in the alignment of the wing towards the direction of the turn; this landmark should not be too far to avoid a too large radius, nor too close to avoid that a too steep bank angle becomes necessary with tailwind;

2°) While turning, try to maintain the distance to the landmark as constant as possible: under light wind conditions, the bank angle variations will be very small; under stronger wind conditions they will obviously be more marked;

3°) Remember the basic rule: the bank angle should constantly vary from minimum value with full headwind. to maximum value with full tailwind (but without exceeding 30°. which is why the landmark should not be too close);

4°) Also remember that the turn must be coordinated throughout, keeping the ball centered while maintaining both airspeed and altitude;

5°) The whole procedure requires a rapid and continuous division of attention between the instruments, the landmark, and the outside world. Particularly the outside world!!! Once again, look-out is paramount, particularly in a heavy traffic environment such as in the airports circuit!!!

B. - FLIGHT TRAINING (Dual 01,00 h. - Total 07/00 h.)

After liftoff, you will immediately take the required pitch attitude to achieve Vx with climb power, and maintain it until the instructor requests you to change to Vy, and possibly further to cruise climb, before levelling off at a specified altitude.

When straight & level, the instructor will cover the D.G. and ask you to pick up headings 090°, 180°, 270° and 000°, alternatively by turning left or right (not necessarily the shortest way).

Next you will be instructed to pick up a few intermediate headings, and finally to roll out on either the North-South or the East-West axis.

The instructor will then take over the controls and demonstrate the effects of accelerations and decelerations on both these axes. He will do this by alternatively lowering and raising the aircraft's nose: relax and, as the speed increases or decreases,

observe the compass deviations when the aircraft is oriented either due East or due West, or lack of them when it is oriented either due North or due South. Next, the instructor will perform a steeply banked turn to show you that the magnetic compass becomes unusable under these conditions.

Once back in level flight you will take over the controls again. The DG will now be uncovered: notice the difference in indicated heading as compared to the magnetic compass and reset the D.G. in accordance with it. You will then be requested to steer a few headings, using this time the D.G. as reference: remember that you should initiate the roll out 5° to 10° before reaching the predetermined heading.

Time permitting, and assuming that the wind velocity is sufficient to ensure an obvious demonstration (if not, it may be postponed to another flight session), the instructor will draw your attention to the wind direction as shown by factory smoke or any other means, tell you to pick up a landmark at 900 left or right of the aircraft and start a turn maintaining a constant medium bank angle: observe the gradual drifting of the aircraft due to the wind effect. You will the reposition the aircraft at the point where the previous turn was initiated, this time trying to maintain a constant radius: this latter exercise should be carried out to the right as well as to the left. Think about dividing your attention between the instruments, the landmark and. . . . . . look-out. At the end of these exercises you will be asked to roll out on a specified heading: think about verifying the

D.G. against the magnetic compass and reset it if necessary.

Although at this stage you should be able to determine the approximate direction of the airport, assuming that the aircraft is VHF equipped and that the possibility exists, you will be asked to request one or more QDM's to rejoin the home base according to the so-called homing procedure (see PILOT NOTE V: “THE VHF TRANSMITTER-RECEIVER") . During this exercise, you should concentrate to maintain both altitude and headings as accurately as possible, but without disregarding the look-out.

Once close to the destination, preferably even after passing overhead if QDM's are used, this flight session will be completed in the same way as the previous ones.

C) QUESTIONARY

01. - State the two purposes of the fluid within the magnetic compass.

02. - State three indications of a fluid leak in the magnetic compass.

03. - Normally speaking, a compass deviation card is valid for a period of _________

04. - What should you check during taxi in relation to the magnetic compass?

05. - Aluminium has no effect on a magnetic compass. True or false?

06. - Assuming that you inadvertently put the headphones close to the magnetic compass, what would happen?

07. - The magnetic compass's needle or annular magnet tends to dip because of the vertical component of the Earth's magnetic field. Nonetheless, it remains perfectly level. How do you explain this?

08. - Magnetic compass turning errors are maximum on the _____ axis, and non-existent on the _____ axis.

09. - Airspeed variation errors are maximum on the _____ axis, and non-existent on the _____ axis.

10. - You wish to pick up a compass heading. The maximum recommended bank angle is _____°

11. - You wish to take a northerly heading on the magnetic compass. Considering the Northern Hemisphere, you should initiate the rollout: a) before reaching the required heading, b) after reaching the required heading.

12. - You wish to take a southerly heading on the magnetic compass. Considering the Northern Hemisphere, you should initiate the rollout: a) before reaching the required heading, b) after reaching the required heading.

13. - In order to pick up heading 090° or 270°, you should initiate the roll out when the magnetic compass shows 090° or 270°. True or false?

14. - You are flying in the Northern Hemisphere. You are steering heading 020° on the magnetic compass. You wish to pick up heading 180° by the shortest way. You should turn to the __________ and roll out on heading ___________?

15. - You are flying in the Northern Hemisphere. You are steering heading 180° on the magnetic compass. You wish to pick up heading 045° by the shortest way. You should turn to the __________ and roll out on heading ___________?

16. - You are flying in the Northern Hemisphere. You are steering heading 045° on the magnetic compass. You wish to pick up heading 270° by the shortest way. You should turn to the ___________ and roll out on heading __________?

17. - You are flying in the Northern Hemisphere. You are steering heading 270° on the magnetic compass with an airspeed of 120 kts. You reduce the speed to 90 kts. The magnetic compass reading will deviate towards the __________ notwithstanding that you keep the heading unchanged. Once the airspeed is stabilized, it will read __________?

18. - Same question as 17, but you increase now the airspeed from 90 kts back to 120 kts.

19. - Turning errors and speed variation errors on the magnetic compass are due to: a) the horizontal component of the Earth's magnetic field, b) the vertical component of the Earths magnetic field, c) both a and b.

20. - The magnetic compass becomes rather unsteady during turbulent conditions. Why? Assuming that no D.G. is available, how can you manage to maintain the heading unchanged?

21. - What should you do so that the D.G. gets directional properties?

22. - State the two type of errors which are likely to affect the D.G.

23. - During flight, you should crosscheck the D.G. with the magnetic compass every _________________ as well as after each significant __________. Explain the reason of these two requirements.

24. - What do you understand by gimbal error in relation to the D.G.?

25. - The D.G. 's gimbal error is likely to occur during turns only. True or false?

26. - State the three required conditions to reset the D.G. with the magnetic compass during flight.

27. - The suction gauge show "in the green". This ensures that the D.G. (or any other pneumatically driven gyroscope) operates correctly. True or false?

28. - You correctly set the pneumatically driven D.G. with the magnetic compass after engine start. Upon reaching the holding point you notice that there is a significant difference between both readings. There is no problem with the vacuum pump and the D.G. IS RESET button remained untouched. Your only conclusion should be that the D.G. operation is unreliable (possibly because of a blocked filter or some kind of mechanical precession). True or false?

29. - A D.G. can be slaved to: a) the usual magnetic compass, b) a flux valve, c) either a or b.

30. - State the advantage of a slaved D.G. as compared to a normal or free system.

31. - A slaved D.G. is not subject the compass deviation errors. True or false?

32. - You wish to fly a circling path around a landmark. Assuming the presence of wind, the bank angle should be minimum with: a) tailwind, b) crosswind from the outside of the turn, c) headwind, d) crosswind from the inside of the turn.

Note: More complete information regarding the magnetic compass and the pressure instruments (altimeter, vertical speed indicator and airspeed indicator are provided in PILOT NOTES VII and VIII. PILOT NOTE IX “GYROSCOPIC INSTRUMENTS”, although mainly related to the advanced training phase, covers the details concerning the directional gyro.

Note: It might be that the flight training associated to this lesson needs to be postponed because of inadequate weather conditions. With this possibility in mind, and in order to avoid resulting delays in the training program, it is strongly recommended to study the contents of lesson 12 in addition to this one.

A.- BRIEFING (01,00 h. - Total 11,00 h.)

We learned in lesson 07 that the minimum airspeed is a function of the maximum angle of attack which, depending on the properties of the wing profile, is somewhere around 16°. As long as the angle of attack is not excessive, the airflow around the wing remains smooth and even (fig. 1). This is sometimes referred to as a laminar airflow (laminaire stroming/écoulement laminaire) . When the angle of attack approaches its maximum value, small eddies (draaikolken/tourbillons) are generated, particularly on the upper side of the wing (fig. 2). These eddies are likely to produce characteristic vibrations, or buffeting, and are amongst the first signs of an impending stall.

The so-called critical angle of attack is reached when the wing develops its maximum lift. If the critical angle of attack is exceeded, the airflow around the wing becomes completely turbulent (fig. 3), and the lift suddenly decreases while the drag increases sharply: the wing is then said to be in a stalled condition (in overtrokken toestand/en perte de sustentation). Under these conditions, the altitude cannot be maintained any longer and, as was probably already demonstrated during the flight session of lesson 07, the aircraft stalls (het vliegtuigscheurt af/l'avion décroche), i.e. it starts sinking at a high rate of descent, usually with a tendency to pitch down rather abruptly, often going along with a rolling motion to the left or to the right, referred to as a “dropping wing”.

It may seem somewhat odd that, when the stall occurs, the nose tends to pitch down, even with the stick in full aft position. This is due to a very specific phenomenon related to the wing's center of pressure (drukpunt/centre de pression). Now, what is the center of pressure? It can be compared to the center of gravity, i.e. the point through which the total weight of the aircraft acts: similarly, the center of pressure is the point through which the total aerodynamic reaction R acts, and which divides into the lift Fz and the drag Fx (fig. 4). During level flight at normal cruising speed, the center of pressure is located at about 1/3 of the wing chord. It has been observed however that, as the angle of attack increases, it moves gradually forward. Incidentally, and rather oddly, this means that a wing is a very unstable affair: indeed, the greater the angle of attack, the more the center of pressure moves forward, and the stronger will be the tendency for the angle of attack to increase . . . . . a rather unhealthy state of things which is only counter acted by the horizontal tailplane, but this is another story. This forward movement of the center of pressure does not continue indefinitely, and comes to an end when the stall occurs, at which moment it suddenly moves backward again, from a most forward position towards the wing's trailing edge, thus causing the pitch down motion which the elevator cannot prevent. 

Be aware that, despite this pitch down motion, the aircraft remains in stalled condition. Indeed, as the aircraft now follows a rather steep descending path, and considering that the relative wind exerts itself in the opposite direction, the angle of attack remains beyond the critical value (fig.5). Thus, in order to recover from a stall it is necessary to bring the angle of attack back within normal values by pushing the stick forward and lowering the nose even more: note however that bringing the stick back to neutral is sufficient and, in most cases, simply releasing it altogether will do the trick.

As long as the aircraft is in stalled condition, the ASI needle will keep oscillating around the so-called stall speed, whereas the VSI will show a rather high rate of descent. The airspeed will only definitively build up again after the angle of attack has been decreased below its critical value.

In order to quickly recover from a stall with the least loss of altitude it is thus necessary to move the stick forward (or, as said, at least to neutral), and to simultaneously advance the throttle lever to maximum power so as to regain the normal cruise speed as rapidly as possible. Obviously, assuming that a stall would occur with the engine inoperative, the only way to regain speed would be to push the stick further forward, thus loosing a significant amount of height.

Besides buffeting, there are other signs and warnings of an impending stall. One of those is the fact that the ailerons loose quite a bit of their efficiency and feel very sloppy: this is because of the reduced airspeed and the fact that they are located outside the propeller's slipstream. Incidentally, note that the aileron drag which was discussed in lesson 04 is usually much more pronounced at high angle of attack and low speed and, when close to the stall, it can have very nasty effects as we will see later. Furthermore, and as was already mentioned earlier, most aircraft are fitted with a stall warning system which is automatically activated about 10 knots before the stall occurs, i.e. when the angle of attack approaches the critical value. But perhaps the most important indication of an impending stall is the ASI itself, an unusual low airspeed being generally indicative of a very high angle of attack.

We mentioned the possibility for a wing to drop at the stall. Athough one can think of a number of possible reasons for this behaviour, it seems that aircraft fitted with tapered wings are particularly prone to it. Anyway, whichever its cause, most pilots instinctively react to the wing drop by means of the ailerons: for instance, assuming that the right wing drops, left stick is applied in an attempt to level the aircraft. But let us analyze what, in fact, is likely to happen: we know that by applying left stick, the downgoing right aileron is supposed to develop more lift than the upgoing left one, and that consequently the aircraft should righten itself. However, the downgoing aileron will cause the angle of attack to increase even more and, as the wing is already in stalled condition, no adequate lift can be obtained, but a noticeable drag increase is inevitable. This additional aileron drag causes the aircraft to yaw towards the low wing so that the situation is no longer a simple stall, but that the aircraft engages into a so-called spin (tolvlucht/vrille), i.e. it engages into a near vertical downgoing trajectory while rotating continuously about its roll axis.

The spin will be discussed at a later stage, but what then is one supposed to do if a wing drops at the stall? Manifestly not using the ailerons! The solution lies with the rudder: if the right wing drops, apply full rudder to the left!! As the rudder is influenced by the propeller's slipstream, it still maintains a considerable degree of aerodynamic efficiency so that, by action of its secondary effect, the wings will resume level attitude.

The natural tendency to use the ailerons against a dropping wing has been the cause of numerous accidents in the early years of aviation history, and even later. To minimize these occurrences, aircraft manufacturers devised the wingtip washout (verdraaing van het vleugelprofiel/torsion de profil d' aile) whereby the angle of incidence (instelhoek/angle d'incidence ou angle de calage), i. e. the angle between the wing chord and the aircraft's LONGITUDINAL AXIS, gradually decreases towards the wing tips, as shown in figure 6. Note that the angle of incidence is a fixed value, usually ±3°, as opposed to the angle of attack which can be varied by the pilot. The purpose of the angle of incidence is to ensure that the fuselage is horizontal during normal cruise flight while the wing is at the most efficient angle in relation to the airflow (note that if the angle of attack would be zero, no lift would be produced), the ideal angle being about 3°. In fact, it can be stated that at normal cruising speed the angle of attack equals the angle of incidence. In case of wingtip washout, the angle of incidence being somewhat less at the aileron's location than it is at the wing root, when the major part of the wing stalls, the tips have not yet exceeded the critical angle, and the ailerons are still capable to counteract a dropping wing if the stick is inadvertently used, a feature which significantly increases safety. Nonetheless, the normal procedure is to use opposite rudder, were it only because this method is applicable to any aircraft type.

On some aircraft, you will notice small V-shaped strips located on the wing root leading edge. These are so-called stall strips, also referred to as spoiler strips, which have the property to locally break the airflow when the critical angle of attack is exceeded, thus causing the wing root to stall before the wingtip so that, also in this case, the ailerons remain functional. Still other methods, such as slots or slats mounted at the wingtip leading edges, produce similar results. The stall speed for any specific aircraft depends on a number of factors:

1°) The weight

The more the weight, the higher will be the stall speed. Indeed, higher weights require a higher angle of attack to produce the required lift. Consequently the critical angle will be reached earlier and the stall speed will be higher.

2°) Use of flaps. slots and slats

As already explained in lesson 07, the use of these systems allows a lower stalling speed.

3°) The location of the center of gravity

The location of the center of gravity (C.G.) depends on how the aircraft is loaded. When the C.G. is forward, the stall speed is higher than when it is located aft. To clarify this statement, let us assume that the aircraft is mainly loaded forward: this will result in a tendency for the nose to pitch down. This tendency must be counteracted by exerting a back pressure on the stick, thus up-elevator. This causes a downward force A on the horizontal tailplane (fig.7). This force is in fact an additional downward load which adds to t-he normal weight G of the aircraft, and thus causes an increase in stall speed.

Incidentally, note that the location C. G. does not only affect the stall speed. Also the fuel consumption increases with a forward C.G., which substantiates the theory here above. In other words, in order to reduce the fuel consumption as much as possible, an aft loading of the aircraft is amongst the various requirements. On the other hand, an aft C.G. decreases the longitudinal stability but, here again, this is another story which will be discussed during the groundcourses.

4°) The thrust

The higher the thrust, the lower the stall speed. Indeed, if we consider an aircraft flying level at high angle of attack, the thrust line is oriented significantly upward. It can thus be decomposed in a horizontal "thrust component" and a vertical "lift component”! which adds to the lift developed by the wings and which remains still active when the wing itself is already stalled, thus effectively delaying the stall (fig. 8).

5°) The bank angle of the wings

When the aircraft is banked, the total wing area decreases. It is thus obvious that the stall speed will be higher under such circumstances (fig. 9).

6°) The load factor

The load factor (belastingsfactor/facteur de charge) can affect the stall speed to a considerable extend. This will be discussed further when studying steep turns and so-called accelerated stalls.

In lesson 07, we discussed the lowest limits of the green and white arcs on the ASI. Recall that these represent respectively the stall speed in clean and in landing configuration. Remember however that, in both cases, these speeds, which are also mentioned numerically in the POH, are only valid for the following specific conditions:

- maximum landing weight (which, on light aircraft, is often the same as the maximum takeoff weight);

- most forward center of gravity;

- wings level;

- engine at idle thrust;

- load factor 1G (will be discussed later) .

Even assuming level flight and idle thrust, the actual stall speeds will usually be slightly lower, firstly because the weight conditions are not fulfilled (certainly not if the maximum takeoff weight is taken into consideration), secondly because the C.G. is not necessarily at its most forward location.

Practical execution of the stall

Stall exercises are subjected to a number of rules and safety precautions:

1°) The height should be at least 3000 ft above ground level (AGL), and the visibility conditions should be adequate;

2°) The exercises may not be carried out overhead major cities or towns, nor overhead crowds;

3°) The seat belt of the occupants must be properly fastened, including the shoulder straps, if any. The belts and straps pertaining to possible empty seats must be properly safe-tied;

4°) Whenever possible, the gyroscopic instruments should be blocked by means of the so-called caging knob to avoid damaging them in case an excessive attitude should occur (it is most unfortunate that such a caging facility is missing on most present day equipment) ;

5°) It must be ensured that no loose objects are present, neither in the cabin nor in the baggage compartment. It is imperative that this is verified before departure;

6°) Before commencing the exercises, one must ensure that no other aircraft are present in the immediate vicinity, and particularly not UNDERNEATH. This should be done by means of two rapid clearing turns, one to the left and one to the right;

7°) The mixture control should be selected to RICH (except if stalls are carried out at unusual high altitudes) for the case that full power would be required for recovery;

8°) The carburettor heating must be selected to HOT;

9°) Assuming a variable pitch propeller, it should be selected to HIGH RPM.

Before executing any form of stall, or series of stalls, it is expected that you carefully carry out all these verifications. Be aware that neglecting to perform them at the final official

flight proficiency test will almost certainly result in failing the examination!!

All these precautions are summed up in the mnemonic SLIMOPALC, which must be understood as follows:

S = Seat belts fastened

L = Loose objects checked

I = Instruments (gyro's caged if possible)

M = Mixture RICH

O = Orientation (to avoid getting lost)

P = Position (not aver a city, town, etc.)

Propeller HIGH RPM

A = Altitude (minimum 3000 ft)

L = Look-out (clearing turns)

C = Carburetor heat HOT

B.- FLIGHT TRAINING (Dual 01,00 h. - Total 08,00 h.)

As stalling exercises will be performed, this flight session requires to climb at least to 3000 ft AGL and adequate visibility conditions. Assuming that the weather is too poor, this lesson (as well as lesson 11) will be postponed and, conditions permitting, be replaced by lesson 12 (TAKEOFF, LANDING, CIRCUIT) and subsequent until suitable conditions prevail. At any rate, the flight session associated to this lesson (as well as lesson 11) must performed before the first solo flight.

Besides the stall practice, this flight session will be a review of all other exercises which have been studied tail now. Expect some questioning during the preflight preparation about matters which you are supposed to know, and which you will certainly know if you solved and reviewed the various questionnaires, those pertaining to the pilot notes as well as those related to the previous briefings.

As far as the flight itself is concerned, remember the need to regularly perform checks of oil pressure, oil temperature, fuel quantity and any other peripheral instruments. Recall the need for look-out. Recall the need for proper trimming during any climb, cruise or descent condition.

Besides the preflight inspection, the various checks and the taxi, you will perform the takeoff, climb initially at Vx then, upon request of the instructor, at Vy until reaching the predetermined cruising altitude.

While climbing at Vy, left and right turns will be carried out towards specified compass headings (D.G. covered). Upon level off, you will proceed at normal cruising speed, maintaining the altitude and the last assigned compass heading for a little while.

The instructor will then request you to steer another few compass headings, always turning by the shortest way.

On the last assigned heading, you will be requested to reduce the speed initially to the lowest limit of the green arc plus 5 to 10 kts (the stall warning will probably sound), while maintaining the altitude. At this speed, perform a level and shallow turn of 90° to the left using an external reference. Rollout and engage immediately in a 90° shallow turn to the right. During this exercise, notice the reduced efficiency of the ailerons and the significant difference in rudder input to maintain the ball centered.

Rollout, maintain the heading using now both external references and the compass. Select the flaps to full down (and extend the landing gear if retractable), maintain altitude and heading and reduce speed to the lowest limit of the white arc, again plus 5 to 10 kts. Note that the additional drag due to the full flaps (and the landing gear) will already cause the aircraft to slow down by itself: adjust the airspeed with the throttle lever, and remember that quite some thrust will be necessary to maintain level flight at such low speed, particularly with the additional drag due to the landing configuration.

Still maintaining altitude and heading, apply full power (retract the gear) and raise the flaps initially to approach configuration (about 10° to 20°), and let the airspeed build up to normal cruise value. Retract the flaps fully when the airspeed approaches the upper limit of the white arc, and stabilize in straight & level flight at normal cruising speed.

With regard to the stalls, momentarily maintain normal cruising speed, the heading and the altitude, and perform the SLIMOPALC checklist in a loud and clear voice. When coming to the L for "Look out, initiate a 360° medium turn to the left using an external reference, roll out and engage immediately in a 360° medium turn to the right, and roll out again: this combines the practice of correct medium turns with the need to look out for other aircraft, particularly below (note that clearing turns are normally fairly steep, and are essentially a safety precaution whereby the look-out is the primary purpose; nonetheless, they should be performed as accurately as possible).

As soon as the SLIMOPALC checklist is completed, reduce power to idle, maintain the altitude by gradually applying back pressure on the stick, keep the wings level and maintain the ball centered by adequate rudder input: don't worry, you will be actively assisted by the instructor during these first attempts. Notice the increasingly higher nose up attitude, notice the buffeting (which is not always very marked on light aircraft) I notice the stall warning activation. Continue applying back pressure on the stick until it is fully aft and, for this first exercise, KEEP IT THERE EVEN WHEN THE STAL OCCURS!!! Assuming that a wing drops, apply full opposite rudder!

The instructor will take over and maintain the aircraft in stalled condition in order to give you the opportunity to relax and to observe the low airspeed value on the ASI, as well as the rate of descent on the VSI. As soon as you have noticed these parameters, he will recover by moving the stick forward (possibly by releasing it altogether), apply full power and, if needed, zoom rapidly back to the minimum safe altitude (this latter manoeuvre might feel a little like an aerobatic, but is the fastest way to regain altitude).

As soon as the aircraft is back in normal cruise flight, you will take over the controls again for a second identical "power off" stall, except for the fact that you will now perform the recovery yourself AFTER the nose has DEFINITELY pitched down, by simultaneously moving the stick towards neutral, possibly applying rudder opposite to the dropping wing, and applying full power. Resume straight & level flight as soon as possible (without climbing) and notice the altitude loss.

You will now repeat the maneuver, but this time starting the recovery procedure AS SOON AS THE STALL OCCURS, so as to keep the altitude loss to a minimum.

The next stall exercise will be initiated as previously but will be carried out in landing configuration. To this purpose, lower the landing gear and extend the flaps to full down when the airspeed reads within the white arc. Start once more the recovery procedure AFTER the nose has DEFINITELY pitched down. However, in this case, be careful not to exceed Vfe: immediately after having moved the stick forward and applied full power, raise the flaps to approach configuration, raise the landing gear, resume straight & level flight and retract the flaps completely.

Be aware that stalls can occur in any flight condition and configuration. More will be learned about them in lesson 28. However, as a demonstration, the instructor will show you what is likely to happen in a poorly coordinated turn (too low speed in combination with too much rudder and the ball showing a skid) with the aircraft in landing configuration: be warned that this demonstration might result in a spin, or at least an incipient spin, which is always rather impressive first time. Nonetheless, as the demonstration is always initiated at a safe altitude, no danger whatsoever is involved.

On the way back to base (and despite all the previous exercises and manoeuvres, you should still be able to determine its general direction), you will perform a last stall exercise, this time in clean configuration with "power on": to this purpose, reduce speed while maintaining heading and altitude, and continue to do so, gradually increasing power when approaching the critical angle of attack in order to maintain the altitude despite the fact that, once the critical angle of attack is exceeded, the lift developed by the wings rapidly decreases: notice the much lower stalling speed . . . . . and an increased possibility for a dropping wing because of the propeller effects.

Time permitting, the previous exercise may be repeated, this time with the aircraft in landing configuration with full flaps . . . . . and fully retracting them when the aircraft is at the verge of Vso.

Notes: - When stalled from level flight, some aircraft have the tendency to start sinking without a distinct pitch down, and loose altitude while merely oscillating somewhat around their pitch and roll axes. If such is the case, a cleaner stall can usually be obtained by pulling the nose some 20° or more above the horizon.

- Some individuals are likely to feel unwell during these first repetitive stall exercises. There is no shame about this. If it happens to you, you should not hesitate to notify your instructor: the session will be either momentarily interrupted until you feel better or, if necessary, the return to base will be initiated. In this latter case, the session will be repeated at a later opportunity.

C. - QUESTIONARY  (You can print the PDF file at the beginning of this lesson to answer the questions in writing, than correct it with your instructor)

01. - What do you understand by a laminar airflow?

02. - State the cause of the buffeting which is likely to develop shortly before the stall occurs.

03. - When at its critical angle of attack, the wing: a) develops the maximum lift, b) develops the maximum drag, c) both a and b, d) stalls.

04. - The basic cause of the stall is: a) too low speed, b) too high angle of attack, c) too little thrust.

05. - Upon stalling, the nose usually has a tendency to pitch down despite the fact that the elevator is fully up. Why?

06. - What do you understand by center of pressure?

07. - A wing in itself is: a) stable, b) unstable.

08. - Despite the fact that the nose pitches down at the stall, the aircraft remains in stalled condition as long as the stick is kept fully aft. Why?

09. - When the aircraft is in stalled condition, the ASI reads: a) an increasing airspeed, b) a decreasing airspeed, c) oscillating around the stall speed.

10. - State your various actions to recover as rapidly as possible from a stalled condition

11. - State four indications of an impending stall.

12. - Due to some inadvertence, you suddenly notice one of the four indications of an unwanted impending stall. What should you do at once to correct this situation?

13. - Upon stalling, the left wing drops. How do you react? Why?

14. - Upon stalling, the left wing drops. You instinctively react by applying stick to the right. What is likely to happen?

15. - What do you understand by wingtip washout? What is its advantage?

16. - What do you understand by the angle of incidence of a wing? What is its use? What is its average value?

17. - What is the purpose of stall strips?

18. - State six factors which are likely to affect the stalling speed.

19. - A forward center of gravity increases the stall speed. Why?

20. - State the influence of a forward center of gravity on the fuel consumption. And on the longitudinal stability?

21. - The stall speed is lower with "power on" than with "power off". Why?

22. - The aircraft stalls at a higher speed when it is banked. Why?

23. - (POH) The published clean configuration stall speed of your training aircraft is __________. For landing configuration, it is __________

24. - State the conditions for which the stall speeds published in the POH are valid.

25. - State the mnemonic applicable before initiating a stall or serie of stalls. What is the meaning of each item?