Advanced Pilot Training: Formation Flying Overview

This rather short indroduction to Formation Flying training and basic techique is taken form: Royal Air Force Flying Training Manual, Part I - Landplanes, Air Publication 129, revised June, 1940, Air Ministry

CHAPTER V

FORMATION FLYING

FUNDAMENTAL PRINCIPLES

1. A formation of aeroplanes is two or more flying in company.

2. The primary objects of formation flying are

(i) To obtain concentration of power for offensive or defensive action as may be required in carrying out any form of air operations.

(ii) To afford mutual support. No aeroplane has yet been designed which possesses a uniformly efficient all-round field of fire ; but a formation should be so organized as to eliminate blind spots and enable fire to be concentrated in any direction.

(iii) To confer moral advantage. Both in attack and defence, the moral effect upon an enemy of a well-drilled formation is far greater than that produced by a number of isolated aeroplanes operating independently. Further, the confidence that aeroplane crews possess in their leader, and the consciousness they have of being supported by others upon whom they are accustomed to rely, increases their morale.

(iv) Formation flying is adopted also as a means to securing the best results in certain form of attack on particular types of land or water objectives.

3. The closest co-operation between the crews of a formation is necessary to efficient collective flying, and is attained only by continual practice.

4. An air formation should not be a heterogeneous assembly of aeroplanes flying together, but must be an organized unit composed of individuals accustomed to work together, operating their craft in definite positions relative to each other, their movements directed by a single leader and their whole formation capable of manoeuvring and operating with the closest cohesion.

5. The achievement of the objects of formation flying in war depends upon :

(i) Leadership.-Good leadership requires balanced judgment, initiative and courage, combined with unselfish devotion to duty.

(ii) Inter communication.-Efficient and speedy means of communication between the leader and other members of the formation is essential to obtain concerted action, and is beneficial to the morale of the individuals in the formation.

(iii) Discipline.-The practice of instant obedience to the directions of the leader and the habit of spontaneous action for the advantage of the formation rather than of the individual.

(iv) Drill.-Skill in combined manoeuvre, in retaining formation under difficult circumstances, and in re-forming rapidly after dispersal.

(v) Fire Tactics.-This comprises skilful control and direction of fire combined with careful aim and economy of ammunition by the formation.

Factors governing the disposition of aeroplanes in formation

6. Although the distribution of aeroplanes in a formation will vary according to the duties to be performed, the type or types of aeroplanes employed and other considerations, certain principles are fundamental, and must be strictly observed. These are:

(i) A formation is commanded and led by a pilot who is immediately responsible for its security, for the course flown, and for the tactics adopted.

(ii) The leader of a formation must be replaceable by a deputy leader, who flies in a definite and pre-arranged position relative to the leader, and must be prepared at any time to take the place and assume the responsibilities of leader.

(iii) The leader must fly in a position from which he can communicate with all his pilots, or, in large formations with leaders of all sub-formations.

(iv) The aeroplanes of the leader and the deputy leader must be marked by some device which can be easily recognised.

(v) No pilot should be stationed directly behind another, since in this position the slipstream of the aeroplane ahead would make it difficult for him to keep station, and his field of fire would be largely obscured.

(vi) The organization of the formation must be simple, easily adopted and easily retained, the fundamental principle being that, in the event of the leader or any other pilot becoming a casualty, his station can be filled with least disorganization and minimum delay by another pilot.

(vii) The formation must be flexible; capable of opening out or closing in on the leader, and of changing to a different formation when necessary.

Note.-The minimum interval and distance at which aeroplanes may be flown in formation in peace-time training practices is laid down in Appendix IV, para. 3. (see below)

Numbering of aeroplanes in formation

7. For the purpose of numbering, the aeroplanes of a formation are assumed to be in " V " formation, the leader being " Number I," the remainder being numbered from starboard to port of the leader, even numbers to starboard, odd numbers to port.

General principles

THE SUB-FORMATION

8. Whilst there may be occasions when two or more squadrons will be required to operate in close support of one another, the basic formation is the squadron, and such combined operations will not materially affect their internal organization. The following paragraphs show how the squadron which is the normal unit, is organized to meet tactical requirements.

9. The purpose of a formation of squadron, or similar strength, is to develop to the full, by concentrating all available aircraft in one composite unit, its power of offence or defence. It has the further advantage that, under the guidance of relatively few experienced leaders, a number of less experienced crews can be brought into action.

10. The size and composition of a squadron formation is governed primarily by the duties which it normally performs, and for which its aircraft are designed.

11. The principal qualities common to all such formations, but varying in importance with the type of operation, and also with its different phases are :

(i) Ease of Control.-The number of aircraft which in close formation can support each other in attack or defence greatly exceeds that which can be effectively controlled by one leader.

(ii) Power of Cohesion.-This calls for good station-keeping qualities. The greater the number of aircraft keeping station on one leader, the more are inadvertent movements at the head of the formation magnified at its extremities. This results in straggling, undue strain on pilots who are not adjacent to the leader, and a consequent reduction in the speed and endurance of the whole.

(iii) Power of Manouvre.-This calls for as much freedom of movement as possible for the leader, combined with instant response by followers to his directions. The greater the number of aircraft under one control, the more will they restrict the leader's movements, and the more sluggish will their response become.

(iv) Flexibility.-There are frequently occasions, as in fighter or torpedo attack, when success is dependent upon the concerted approach of a number of small, manoeuvrable units, from widely separated points in converging directions. In bombing it may also be necessary to deliver several consecutive attacks instead of one mass attack.

12. In order to satisfy the foregoing requirements, it is clearly necessary to divide the squadron into a number of sub-formations, the strength of which will again vary with the type of aircraft and duty it normally performs.

13. In deciding the strength and disposition of aircraft in subformations it should be borne in mind that power of cohesion and manoeuvre are of greater consequence than any other quality. It should be as small as is consistent with limiting the number of sub-formations in the parent formation to that which can be effectively controlled. It will rarely be necessary for its strength to exceed three aircraft, and there will be occasions when the necessary manoeuvrability can best be attained by employing sub-formations of two aircraft.

14. When a particular tactical or strategical object cannot be achieved by a small sub-formation, two or more such units can readily be combined.

"Close,"  "Open" and "Cruising" formations

15. The spacing of sub-formations, and of aircraft within sub-formations, will vary according to the type of aircraft, the duty upon which they are engaged and the tactical situation.

16. " Close " formation is that in which aircraft are separated by the minimum amount allowed by -regulations in peace or expedient in war.

17. Examples of tactical situations in which close formation confers an advantage are

(i) In Attack.

(a) When it is desired to confine the distribution of bombs or torpedoes, to a small space.

(b) To facilitate the co-ordination and concentration of machine-gun fire.

(ii) In Defence.

(a) To ensure the maximum concentration of supporting fire.

(b) To present as small a target as possible.

(c) To facilitate evasion by manoeuvre.

18. " Open " formation is the term applied broadly to any formation in which sub-formations or aircraft are not in "close" formation, and includes " cruising " formation.

19. Examples of situations in which " Open " formation may be resorted to are :

(i) When the primary task is observation of the air or ground.

(ii) When sub-formations separate to fly through clouds.

(iii) When sub-formations equipped with R/T are distributed both above and below cloud layers.

(iv) When it is desired to straddle a bombing objective with the object of minimizing the chance of missing.

20. Close formation flying calls for the unremitting attention of all the pilots, and for a precision in flying which if unduly protracted causes unnecessary strain. Whenever possible, therefore, flights and individual aircraft should open to " cruising " formation. In this formation aircraft should be sufficiently far apart for pilots to relax a little from their former state of vigilance. In " cruising " formation, sub-formation leaders should be able to study the ground, with a view to knowing their position if called upon to lead.

21. In air drill, pilots will be taught to form close formation from open and cruising formation, and vice versa, with rapidity and precision.

Air drill

22. Standard Instructions for Air Drill in The Royal Air Force are given in Appendix IV, and should be carefully studied by all pilots and crews under training in formation flying.

Ground instruction

23. Ground instruction forms the basis of elementary training, and should consist of lectures illustrated by drawings, models and photographs; it should include the following subjects:

(i) Discipline.-Discipline both on the ground and in the air, including punctuality and instant obedience to all commands of the leader.

(ii) Use of the throttle in maintaining position. One of the first essentials to success in formation-flying is that every pilot should thoroughly understand how to use his engine throttle. He will find it necessary to use it constantly throughout a flight, and must train himself to do so instinctively.

(iii) Types of formation. The pilot should be taught the types of formations laid down in the Standard Instructions for Air Drill, see Appendix IV.

(iv) Choice of Position. The advantages and disadvantages of various stations in formation should be examined by means of models. Two rules which are of general application are :

(a) Pilots within formation must always be in a position to see the aeroplane which is acting as their guide.

(b) Pilots must not fly, in the slipstream of other aircraft in the formation.

(v) Intercommunication (see paras. 59-65 of this Chapter). -Pilots should be taught all elementary signals, methods of communicating by signal cartridge, and the use of the wireless telephone. It should be pointed out how essential it is to avoid all unnecessary communications, and that all signals should be given clearly and precisely.

24. Before attempting to carry out an evolution in the air, pilots should be thoroughly acquainted with the various phases of the movement. With this object in view the instructor should place the pilots of the formation he is instructing in positions on the ground similar to those they will adopt in the air, and cause them to carry out, as far as possible on the ground, with a standard infantry pace and step, the movements they will be called upon to execute with their aeroplanes. In this manner pilots become familiar with their positions and more" readily fall into place" in the air.

General principles of air training

25. Training in formation flying should be directed towards teaching the pilot how to work in combination with others, and to develop in him such a high state of efficiency in flying that, in the stress of battle, whilst flying and maintaining his station, he will at the same time be able to devote full attention to the use of his weapons, and to manoeuvring according to the directions of his leader. This requires careful training and constant practice in air drill to produce cohesion and the habit of instant obedience to a leader.

26. Instructors should bear in mind that a formation, though apparently perfect when manoeuvring over the aerodrome, will have its cohesion put to a severe test when flying under heavy fire, or when re-forming after a long and punishing engagement.

27. The preliminary training of pilots should aim at developing

(i) Confidence to fly in close proximity to other aeroplanes.

(ii) Ability to maintain station.

(iii) Vigilance, i.e., the faculty of observing the leader's signals, and at the same time observing the approach of any other aeroplane and recognising it.

(iv) Efficiency in flying drill, since in the air, as on the ground, the basis of successful co-operation is drill.

When satisfactory progress has been made in these essentials, pilots should be taught how to apply what they have learnt to the varied conditions which they may encounter in war.

Sub-formation training

28. Training should be progressive, beginning with the training of the smallest sub-formation and continuing with the, training of the successively larger formations.

29. In his initial stages an inexperienced pilot should practise formation flying in an open sub-formation until proficient. He should then receive instruction in flying in close sub-formation of two or three. When he has overcome the disinclination to fly in the vicinity of other aeroplanes, and has acquired the habit of conforming instantly to their movements, he may be permitted to take his place in larger formations.

30. As pilots progress, the instructor, acting as leader, should occasionally vary his speed until pupils can maintain their correct station under varying conditions. Straggling should never be allowed, even during the initial stages of training, as efficiency in the attack and security in defence depend on the maintenance of station by each pilot. A pilot who lags behind the remainder of the formation not only runs the risk of being cut off himself, but endangers the lives of others by greatly adding to the difficulties of the leader.

31. Towards the end of a pupil's early training the petrol consumption of his engine should be checked and compared with that of the instructor. This should be done especially when high flying is being practised, since accurate use of the altitude control will reduce petrol consumption and thus lengthen the working range of a patrol.

Changing direction

32. When proficiency in keeping station while flying on a straight course has been acquired, the instructor should explain the procedure adopted in turning, and demonstrate any cautionary signals he may use before altering course.

33. Instruction should begin with gentle turns which should be carried out without a change in the relative positions of pilots. No change of direction should be initiated by the leader without first giving a cautionary signal so as to allow the formation to close up. A simple turn is carried out in the following manner: The leader gives the cautionary signal as in para. 64 (iii) and, after allowing the formation time to close up, turns in the required direction. Pilots flying on the inner flank of the turn, throttle down and reduce their speed while pilots on the outer flank accelerate and maintain their station (see para. 45). The leader should continue to fly at normal cruising speed until the turn is completed and the formation closed up (see Fig. 85).

34. When pilots have attained proficiency in keeping station through all simple manoeuvres, the number of pilots taking part in the formation may be increased, and exercises in diving and climbing, and in breaking up and re-forming, should be begun.

FLIGHT AND SQUADRON TRAINING

General

35. Training should now be directed so as to render flights, squadrons and larger formations capable of manoeuvre in battle.

36. The instruction of individuals in flying, air fighting and in elementary air drill should not be considered as limited to certain definite periods; advantage must be taken of any opportunities which may arise during advanced collective training to raise the standard of efficiency of pilots by individual tuition. Special attention should be paid to the training of subordinate commanders.

37. Drill should commence in flight formation, each flight commander instructing and leading his own flight; it should aim primarily at developing discipline, cohesion and the habit of instant obedience to the signals of the leader.

38. Practical training in leading sub-formations is of supreme importance, and, with this object in view, a sub-formation should be regarded as a distinct unit, commanded throughout its advanced training by its own leader. The flight commander is, however, responsible that all the pilots of his flight receive ample practice in leadership to qualify them to take his place if necessary.

39. When flights have become efficient in elementary drill, they should be trained in the more complicated, manoeuvres required in war; this training should include :

(i) Taking-off in formation, and keeping station during a climb up to high altitudes with full war-load.

(ii) Diving in formation.

(iii) Opening and re-forming close formation.

(iv) Flying through clouds.

40. Concurrently with this stage of training in the air, lectures should be delivered on the following subjects

(i) Use of patrols.

(ii) Co-operation in the air.

(iii) -Advantage and disadvantages of different formations

Getting into formation

41. The methods of forming up vary according to circumstances, but may be classed under two headings

(i) Taking-off in formation, and

(ii) Forming up in the air.

42. " Taking-off in formation " is the most satisfactory method, especially for single-seater aeroplanes, and is comparativelv easy, provided the aerodrome is not surrounded by obstacles. Pilots taxi to their allotted positions head to wind, and, as soon as they are ready to take-off raise their arm vertically as a signal and look towards the leader. The leader waits until he receives the " readiness " signal from the whole formation ; he then raises his arm vertically as a signal to " Prepare to take-off " (see para. 64 (i) ). On dropping his arm he opens his throttle and takes-off, the remainder of the formation following suit. The leader should fly straight ahead, and should throttle down as soon as he has reached a few hundred feet in height in order to allow the formation to close up before he attempts a change in direction.

43. The method of " forming up in the air " is used for large aeroplanes or when the aerodrome in use is small or surrounded by obstacles, or when some of the pilots are not considered sufficiently experienced to take-off in formation. The leader takes off at the time appointed for the start and, having gained sufficient height, throttles down and flies in large circles round the aerodrome. The remaining pilots take-off in succession and gain their pre-arranged position in formation as rapidly as possible. As soon as the formation is satisfactory, the leader makes off in the desired direction, throttling down at first, if necessary, to allow any stragglers to close up.

44. A similar procedure to the foregoing is adopted when circumstances do not permit of the whole formation taking-off together, but do permit of the sub-formations doing so. The leading or pivotal sub-formation will take-off first and circle round the aerodrome until the other sub-formations have gained their relative position.

Station-keeping

45. Although the rate at which a leader should fly varies according to the requirements of the moment, it will necessarily be limited to the speed of the slowest aeroplane in the formation. The leader should never reduce his speed to such an extent that pilots flying astern of him will have difficulty in maintaining their stations without overshooting. Deceleration, following the closing of the throttle, in aircraft possessing low drag characteristics is slow. Caution must be exercised in the use of the throttle. Pilots on the inside of a turn must throttle down early to avoid over-shooting. The leader should give his pilots due warning of any change of course and never turn more suddenly than is necessary. A pilot accelerating to regain position in formation must throttle back early to avoid over-shooting. It is important that a leader should himself have had experience of flying in all the various positions of the formation so that he may realise the difficulties of his pilots. Frequent discussions should take place at which the leader should explain his reasons for adopting various formations, and should encourage other pilots to make alternative suggestions.

Breaking formation

46. The following will be the normal procedure adopted by aircraft when breaking formation :

(i) " V " formations will break up as follows

(a) Formation leader will make executive signal for breaking formation as laid down in para. 64 (vii).

(b) The leader will maintain his course and speed throughout.

(c) The aircraft on either side of the leader in the extreme flank positions will immediately turn outwards. When these aircraft are clear, the movement will be repeated by the aircraft then on the flank, and so on until the formation is broken up.

(ii)    Formations of two or more flights or sub-flights, each being in " V " formation on its leader, will break formation as follows.

(a) Formation leader will make executive signal for breaking formation as laid down in para. 64 (vi).

(b) The subordinate flight or sub-flight leaders will open out their flights or sub-flights from the formation and, when clear, will cease flying in formation on the leader.

(c) The flights or sub-flights will then break formation as in para. (i) above.

(iii)   In the case of Fleet Air Arm aircraft, when formation has been broken preparatory to " landing on" in a carrier, all aircraft will circle the carrier anti-clockwise, keeping well clear of aircraft actually landing on.

Landing after formation flying

47. Where circumstances are favourable as regards size and suitability of the aerodrome and prevailing weather conditions, landing in squadron formation will be carried out. When conditions are unsuited to squadron landings, it will be carried out by flights in succession. In order to avoid confusion and consequent risk of collision, the order in which sub-formations or individual aircraft are to land must be previously arranged.

48. Unless specific orders to the contrary have been given by the formation leader, formations approaching an aerodrome at which it is intended to break formation before landing, are to form echelon to the right in accordance with Appendix IV before entering the circuit zone.

49. Sub-formations are to land in the sequence of their disposition in echelon. Unless contrary instructions have been given, each sub-formation on breaking off to land is itself to form echelon to the right, and ultimately individual aircraft are to land in the sequence of their position in the flight echelon formation.

Formation leadership

50. The usefulness and ultimate success of a formation depends to a large extent on the skill and conscientiousness of its leader and on the Confidence he inspires. The power of good leadership can be acquired, to some extent, by practice and experience; and it is therefore of the utmost importance that instructors should frequently arrange to be replaced by other pilots during a flight. Thus, while the pupil gradually acquires the experience and confidence necessary to good leadership, the instructor without actually taking part in the formation can fly in its vicinity so as to be able to criticise the leaders' manoeuvres.

51. It should be explained that the responsibilities of a leader do not end with placing himself in front, for others to follow, but combine the duties of a commander with those of a guide. He is responsible, not only for maintaining direction and for deciding when to return, but for regulating his speed by flying and manoeuvring judiciously, so that the formation will have no difficulty in maintaining its cohesion. he should keep constant watch over his formation and regulate his speed by that of its slowest member.

52. Intimate co-operation between the leader and his pilots is essential to success, and is best assured by the development of that mutual confidence which springs from constant practice and association together. The growth of mutual confidence will be expedited if the leader

(i) keeps constant watch over his pilots

(ii) always issues a cautionary signal before initiating a fresh manoeuvre ;

(iii) never loses his way; and if the remaining pilots of the formation

(i) always watch for the leader's signals

(ii) carry out all orders promptly;

(iii) keep station.

53. Perfect co-operation can only be attained after a great deal of practice; no opportunity should, therefore, be neglected of training a unit under conditions resembling, as nearly as possible, those of war.

54. The first duty of a leader is to appoint a deputy leader whose aeroplane will bear distinctive markings. The deputy leader must be familiar with the duties and intentions of the leader, so that, in the event of the latter becoming a casualty, the formation will be able to continue its work without loss of efficiency. The actual position of the deputy leader in the formation with relation to the leader will depend largely on the disposition of the remaining pilots; the fundamental principle being that, if the leader is compelled to fall out, the deputy leader should be able to reach his new station as rapidly and as easily as possible. Any consequent alteration necessitated in the respective stations of other pilots should be reduced to a minimum.

ADVIATION TRANING

Preparation for a flight in formation

55. Before starting on a flight in formation, the leader should collect all pilots and explain clearly and precisely to them

(i) The object of the flight.

(ii) The time at which pilots are to have their aeroplanes in position with engines running. (This will usually be five minutes before the time of start ; but will depend on the type of engine and method of getting away.)

(iii) The method of taking-off.

(iv) The position of individual aeroplanes for taking-off.

(v) The type of cruising formation to be adopted in the air and the exact position of each aeroplane in it.

(vi) Special signals to be employed.

56. Discipline on the ground during preparations for a start is just as necessary as it is in the air. Even in the initial stages of instruction, definite orders should invariably be issued giving the time of start and composition of the formation so that pilots and crews may cultivate the habit of punctuality. The hour detailed for the start must be the time at which the leader is actually to leave the ground; at that time the remainder of the formation must be in their respective positions ready to take off. The time required to complete the necessary preparations for a flight will vary according to the circumstances, but pilots and crews should be on the aerodrome at least half-an-hour before the time detailed for the start-, so that they may :

(i) Carry out a final inspection of their aeroplanes.

(ii) Check their armament and ammunition.

(iii) Prepare maps and equipment and put on flying clothing.

(iv) Check their radio-telephony or other signalling apparatus and any other special apparatus such as oxygen cylinders.

Operational exercises

57. When individual pilots are sufficiently trained in air drill and in the elementary principles of air fighting, flight, squadron and wing formations should be sent into the air to carry out definite schemes to illustrate various phases of air warfare. Each scheme should exemplify some particular principle, and be designed to teach some definite lesson, which should be explained beforehand at a short conference held on the ground. Simplicity is essential, since complicated manoeuvres are liable to fail in action. Each pilot should be given definite instructions, as in para. 55 above. Special attention should be paid to the training of leaders in grasping and dealing rapidly with situations, and to the re-forming of formations after they have become disorganized and their leaders incapacitated. These exercises should approximate, as far as possible, to service conditions; and pilots should not be allowed to employ, during peace operations, methods which would be impossible in war.

58. At the conclusion of each flight, a conference should be held at which it should be shown how far the principles, referred to in the preliminary conference, have been successfully applied to each situation, where these principles have been violated, and how faults can be avoided in future.

INTERCOMMUNICATION

General

59. The value of an efficient method of intercommunication between the aeroplanes of a formation is manifest.

60. Detailed procedure for the operation of radio-telephony communication is contained in Chapter XXI-R.A.F. Signal Manual, Part III, and its employment in training in Air Drill is illustrated in Appendix IV.

61. For use in emergency, or when radio-telephony is unavailable or its employment undesirable, visual signals may be used in certain types of aeroplanes and under suitable conditions. These signals may be made by means of firing cartridges or by the pilot manoeuvring his aeroplane and signalling with his arms. A simple code has been standardised and is given below. For a complete list of Air Signals see Appendix IV.

Appendix IV, para. 3

3. Station Keeping

(i) Describing the relative positions of aeroplanes, or sub-formations, in a formation

(a) When two or more aeroplanes or sub-formations are flying in company they are said to be separated by "intervals" which, for ordinary purposes, may be measured between the nearest adjacent points of aeroplanes or sub-formations, thus :

When necessary, intervals may be more exactly described by the method given in sub-para. (b) below.

(b) The interval separating an aeroplane or sub-formation from another may be exactly indicated in the following terms, denoting the three dimensions :

Lateral interval

The shortest measurement horizontally between vertical planes drawn through adjacent wing-tips of adjacent aeroplanes and parallel to the direction of flight (see Fig.9).

2. Fore and aft intervals

The shortest measurement horizontally between vertical planes drawn through the centre of the wings of adjacent aeroplanes and at right angles to the direction of flight (see Fig. 10).

3. Vertical interval

The shortest measurement vertically between horizontal planes drawn through-the centre of the wings of adjacent aeroplanes (see Fig. 11).

(c) Intervals are measured and described in terms of spans of the aeroplane or sub-formation concerned. But vertical intervals may be expressed in feet if greater exactitude is required.

(d) In describing a formation, the word " echelon " is used with reference to the horizontal plane only.

(a) In the vertical plane, the word " stepped " is used followed by the word "upwards" or "downwards " to indicate whether the subordinate aeroplanes or sub-formations are disposed at a vertical interval above or below the leader.

f) In describing a formation, or in an order given by radio-telephony, the point of reference is always the leader of the formation. For instance, " flight echelon port " means that all aeroplanes of a flight are in echelon to port of the leader, " flight line astern " indicates that the aeroplanes are in line astern of the leader.

(ii)    Standard Instructions for station-keeping for aeroplanes flying in formation

(a) The observance of regulations laying down the minimum intervals which may be maintained between aeroplanes flying in formation must be strictly enforced. Such regulations must be included in all station and unit flying orders and all flying personnel are to sign as having seen and understood them.

b) Aeroplanes are not to fly in formation so disposed that the interval between the nearest points of adjacent aeroplanes are less than one span of the aeroplanes engaged. Exception to this rule is made only in the case of single-engined aeroplanes when disposed in echelon, as, for example, in flight or squadron " V ". In this type of formation the intervals between nearest points of adjacent aeroplanes may be not less than half a span of the aeroplanes engaged (see Fig. 7). Permission may also be granted by A.O.C. for Fighter aircraft to fly in formation at less than half span interval subject to the provisos that the authority is to be granted very sparingly and only for specific displays and practices therefor; also that only thoroughly experienced and specially selected pilots are to receive the authority for this type of flying.

Note.-In this connection discrimination is made between single-engined and multi-engined aeroplanes on account of the relative manoeuvrability of the types at present in service. In the event of more manoeuvrable multi-engined aeroplanes being employed, A.O.s.C. should apply to higher authority for permission to modify these instructions accordingly.

(c) Aeroplanes flying in formation are to be so disposed that each pilot can see the aeroplane which is acting as his guide.

(d) Sub-formations are not to fly in formation so disposed that the intervals between, nearest points of adjacent sub-formations are less, when in " V " or' Echelon," than half the total span of the sub-formations engaged ; or when in line astern less than one and a quarter total spans of the sub-formations concerned. This rule will not apply to squadron and wing formations in which aeroplanes are disposed individually (see Fig. 8).

(a) The above rules prescribe the utmost proximity at which aeroplanes axe permitted to fly. In no circumstances are they to fly closer to each other, either in formation or in the course of changing formation. A.O's.C. should, however, issue instructions that greater distances than the above must be maintained between aeroplanes in formation should the standard of ability of pilots, special peculiarities of the type of aeroplane (vide note to para. 3 (ii) (b) above), or other considerations render such action desirable. Corresponding alterations must be made in the measurements given in the Air Drill Detail, since these are based upon the minima.

(iii) Line of bearing from leader

The line of bearing from the leader upon which aeroplanes or subformations are to be stationed when in " V " or Echelon formation is not laid down. Compliance with sub-para. 3 (ii) (b) and (d) above and the use of minimum intervals will necessitate a line of bearing depending upon the proportions of the wings and elevators of the aeroplanes concerned.

(iv) Leading unit forms datum point

In Air Drill Detail it is laid down that the leading unit of a formation shall maintain a constant speed and course with the object of providing a relatively fixed datum point upon which other units may take station, but it may be found desirable, when using aeroplanes which have not a large speed range, for the leading unit to increase speed up to approximately 10 per cent., in order that the following units may change station or disposition more readily. But this practice should be avoided wherever possible since it is obviously safer if manoeuvres are performed with reference to a relatively constant datum point provided by the leading unit maintaining a constant speed and course.

(v) Station-keeping in "V" formation

In all " V " formations the port units are to conform in station keeping to the station maintained by the starboard units.