Allied Air Power Doctrine: Royal Air Force War Manual; Volume I - Chapter 11: Employment of Air Forces with the Navy
General Considerations
1. Aircraft may be used directly against the sea power of an enemy in four ways :
(i) By attacking its fleet either at sea or in harbour from shore bases.
(ii) By attacking harbours, dockyards, and fuel reserves. Operations of this nature are similar in principle to other bombing attacks and are described in Chapter VIII,
(iii) By reconnaissance from coastal or land bases.
(iv) By operating with the fleet itself. This is the particular province of the Fleet Air Arm.
2. Most naval formations are dependent on aircraft for the efficient performance of certain services, and with the development of aircraft this dependence is likely to assume greater importance.
3. Considerable assistance may be given to naval forces by the co-operation of shore-based aircraft, particularly in the protection of sea communications and trade routes, and in the defence of naval bases and commercial harbours. This is the case whether the enemy is attacking by sea or from the air.
4. In general, however, the air requirements of the fleet at sea are met by the Fleet Air Arm, the aircraft of which are allotted by the Admiralty to the commander-in-chief of the principal fleets. The Fleet Air Arm is trained, organized and developed for use in fleet operations, and provides a definite tactical weapon to be used against an enemy fleet.
5. It is therefore proposed to examine the subject under two main headings :
(i) Operations by shore-based aircraft.
(ii) Operations by the Fleet Air Arm.
6. Attention is drawn to Chapter IV, paragraphs 2 to 12, in which the functions of the Navy are briefly described.
Operations by Shore-based Aircraft
7. In certain circumstances, any unit of the air force may be required to operate against an enemy's naval forces, but under normal conditions the greater part of such work will be done by units equipped with flying boats, floatplanes, or torpedo-bombers.
8. Shore-based aircraft will not normally be required to do the duties proper to the Fleet Air Arm, although all available aircraft would be employed against enemy ships if a fleet action were fought within range of their bases.
9. The principal duties which fall to shore-based aircraft are as follows :
(i) Anti-submarine patrols.
(ii) Convoy escort.
(iii) Reconnaissance.
(iv) Bombing and torpedo attack.
The manner in which these duties are carried out is described in the Flying Training Manual, Part IV (Air Publication 1256), and only the broad principles will be given here. Some of the statements made in the following paragraphs are applicable also to the section of this chapter dealing with the Fleet Air Arm. Where necessary, the various problems are discussed in both sections, but from somewhat different points of view.
Anti-submarine patrols
10. Aircraft provide one of the most valuable means of counteracting submarine attacks. In favourable circumstances they are able to bomb and destroy a submarine, but their value is largely due to their ability to force the submarine to dive, thus reducing its mobility and range of vision.
11. In order to understand the effectiveness of aircraft patrols, it is necessary to have a knowledge of the limitations of the submarine. When on the surface, this type of vessel is driven by internal combustion engines, but owing to the large quantity of air required by these engines it is impossible to use them whilst submerged. Electric motors are therefore used for propelling the vessel below the surface. The motors are run from batteries which frequently require recharging, but which give sufficient power for the submarine to move at slow speed for considerable periods. If forced to use full speed, however, their endurance is reduced in most cases to as little as one hour. The submarine must come to the surface to recharge batteries. This is usually done during the night so as to avoid detection. Submarines are also likely to be found on the surface at dawn checking their position. They will often endeavour to check their position by sighting some well-known landmark or buoy.
12. Patrols should not be arranged with undue regularity. Unless sufficient aircraft are available to maintain a continuous watch on an area, irregular patrols are more likely to be successful. After undergoing a series of surprise attacks in a particular area, submarines working in the vicinity will spend much of their time submerged with consequent reduction in mobility and vision, and may ultimately abandon the area as being unsuitable for effective operations.
Convoy escort
13. A convoy consists of a fleet of merchant ships escorted by sufficient naval forces, which may include Fleet Air Arm aircraft, to protect it against probable attack by surface raiders and submarines. When possible a convoy is composed of a number of ships capable of steaming at approximately the same speed. Thus there are fast and slow convoys, the average speed being between about 8 knots for a slow convoy and 12 knots for a fast convoy. The size of the convoy depends on the means available to control and protect it at sea.
14. A convoy is assembled in protected waters, and generally sails from the assembly area so as to pass through danger areas at night. The areas where shipping becomes most numerous, termed " focal " and " terminal " areas, constitute the danger zones.
15. The object of aircraft escort is to co-operate with the surface escort by giving warning of the approach of enemy ships, submarines, or aircraft, and by attacking them.
16. The distance to which it is possible to escort out-going convoys, or at which to meet incoming convoys, depends on the number and type of aircraft available. Various types of aircraft may be used for convoy escort, each having its special advantages. The most suitable type is the flying boat, which possesses considerable endurance and good sea-keeping qualities. Small airships possess the qualities of good station-keeping, endurance, and range, but are at a disadvantage in windy weather, are vulnerable to gunfire and air attack and are slow in attack when compared with other aircraft.
17. When escorting a convoy the pilot and observer must remember that the main object is to get the convoy through safely. For this reason, the air escort must not allow itself to be drawn away from the vicinity of the convoy. All submarines sighted should be immediately attacked and reported, with the object of destroying them or forcing them to remain submerged until the convoy has passed out of range.
18. Aircraft should search up to a distance of about 15 miles ahead and 10 miles on either side of a convoy. The submarine may possibly be on the surface some miles ahead, observing the masts and smoke of the convoy, so as to be able to manoeuvre into a position from which to make an attack.
19. Before dark the aircraft should also search astern for submarines which, if there, are in a good position to close the convoy on the surface during the dark hours.
Reconnaissance
20. Shore-based aircraft may he employed on reconnaissance duties such as the following :
(i) Local reconnaissance in the vicinity of a port or coastline, usually in co-operation with other defence forces.
(ii) Distant reconnaissance to obtain information on some specific point, such as the position of a hostile force, or the presence of enemy vessels in a distant harbour.
21. The duty of escorting the main fleet into and out of harbour will, wherever possible, he carried out by shore-based aircraft. This will relieve the aircraft carriers of the task, and conserve the Fleet Air Arm for its proper functions. Should enemy forces be located, Fleet Air Arm aircraft would be flown off and undertake the duties described in subsequent paragraphs.
Bomb and torpedo attacks
22. Opportunities for the employment of shore-based aircraft to attack enemy ships with bombs or torpedoes may occur whenever enemy ships are within range. The following circumstances will, probably, particularly favour attack by shore-based aircraft :
(i) When enemy ships attempt to pass through narrow waters within range of an aircraft base.
(ii) When enemy vessels are lying in a harbour or anchorage within range.
(iii) On the approach of a hostile expeditionary force, or of a force intending to bombard the coast.
Reconnaissance to locate and keep in touch with the enemy will be important. Otherwise the attacking air-craft will spend valuable time searching for their objectives.
23. Torpedo attacks on ships in harbour require tactics differing from those employed against ships at sea. Torpedoes often dive considerably below their set depth, and depth of water must therefore be considered when planning a harbour attack. Consideration must also be given to the nature of the surrounding country, the presence of shore-based fighters, and the existence of any system of detecting the approach of aircraft. The main effort of the attacking forces should be directed against the enemy capital ships, but in exceptional circumstances the most effective policy may be to attack the fleet auxiliaries. For example, at the moment of attack the enemy fleet may be approaching harbour to refuel, heavily screened by destroyers and presenting a difficult target. The oilers on which the fleet depends for its future movements will probably be lying at anchor offering an easy target, and their destruction may in the long run achieve more decisive results than an attack on the hostile battle fleet. It sometimes happens that the latter will place auxiliaries alongside as a protection against torpedo attack. In this case it may be preferable to attack with bombs.
24. Enemy vessels engaged in bombarding will frequently employ smoke screens to protect themselves from shore batteries. Defending aircraft may be able to make use of these screens when making their attacks on the bombarding vessels. In every case it is important that aircraft should report the movements of the bombarding force.
Combined operations
25. The employment of air forces in opposing or assisting a landing is described in Chapter XIII.
Co-operation at night
26. The difficulties of sighting and identifying ships at night are considerable. At present it is only in very favourable conditions of light and visibility that aircraft will be able to operate with naval forces at night. Considerable help will be given, however, if it is possible to illuminate enemy vessels with parachute flares, and thus enable our own naval forces to attack. Moreover, if the enemy forces are in harbour, or their position is other-wise known with sufficient accuracy, flares will provide an opportunity for night attacks by aircraft. So long as the target can be clearly seen, bombing attacks by night should be very nearly as accurate as those by day, and the attacking forces will derive considerable assistance from the concealment afforded by darkness.
Operations by the Fleet Air Arm
27. Without special facilities, aircraft are unable to operate over the open sea for more than a limited period. Their fuel endurance is small, and it is usually quite impracticable for seaplanes to alight and refuel except in sheltered waters. These considerations have led to the introduction and development of the aircraft carrier, a vessel which fulfils the role of a mobile aerodrome for aircraft with land undercarriages.
28. The aircraft requirements of the main fleet are considerable, whilst the size and number of aircraft carriers are limited by economic restrictions and inter-national agreements. It follows that, in a war with another maritime power, all the available carriers will normally be required for fleet operations.
29. The wide distribution and supreme importance of our trade routes necessitate a dispersion of cruiser strength, and it is most desirable that these vessels shall not be deprived of the services of aircraft. Since carriers can seldom be spared for the purpose, it is the policy to fit cruisers to carry aircraft on catapults. The use of float undercarriages makes it possible in favourable circumstances to hoist the aircraft on board again without damage. Although there are serious limitations to this arrangement, it is considered that they are outweighed by the advantages to be gained.
30. In local operations it will frequently happen that carrier-borne aircraft can be brought to the scene of action at an early stage. Examples of this include an expedition against a minor power, involving some form of combined operation. The principles of the employment of aircraft in these operations are similar to those described elsewhere in this manual, particularly in paragraphs 29-43 of Chapter XIII. No further mention will be made of them in the present chapter.
31. Fleet aircraft operate in relation to moving objects. The vessels from which they work are always in motion, and most of the flying takes place over the sea out of sight of land. Accurate navigation is therefore essential. Single-seater aircraft cannot be navigated with the necessary degree of accuracy. Unless they are accompanied to their objectives by other aircraft, their operations are usually restricted to a relatively small area.
32. Aircraft carriers are vulnerable to attack by air and sea forces. Moreover, aircraft can only land on the deck of a carrier when the latter is steaming into wind. It follows that the movements of carriers are governed by the strength and direction of the wind, by the number and type of aircraft to be flown off and subsequently landed, and by the position of enemy forces. If the wind is light, a carrier may get seriously out of position in a few hours. Other factors affecting the ability of a carrier to operate its aircraft include the size and number of its decks and hangars, the speed and number of the aircraft lifts, and the speed of the ship herself. In general, it may be assumed that aircraft can be operated in any reasonable weather,
33. Aircraft can fly off a carrier during darkness without any serious difficulty. Landing-on at present requires considerable illumination of the deck, which is undesirable if enemy vessels are likely to be in the vicinity. At present the difficulty of locating and identifying ships at night is so great that aircraft are unlikely to be of much value during darkness. By taking off before dawn, however, they may be in a suitable position to commence operations when the light permits.
34. The characteristics of ship-borne aircraft are given in para. 24 of Chapter IV. Certain departures from normal design are involved, and this adds somewhat to the structural weight, with a corresponding reduction in performance. The tendency is for these disadvantages to disappear. The majority of aircraft for ship's use are designed to take alternative sea or land undercarriages. A land undercarriage, however, is lighter and considerably more durable, and render aircraft much quicker to handle in a hangar or on the deck.
35. Aircraft carriers cannot provide the total number of aircraft required in a fleet action. Battleships, battle cruisers, and the cruisers accompanying the fleet will therefore carry aircraft on catapults. The heavier ships will generally be provided with one spotter-reconnaissance aircraft and one fighter aircraft. The cruisers will carry one single-seater or two-seater fighter aeroplane. Fighting aircraft working from independent and perhaps widely scattered points of departure will not possess so high a tactical value as formations operating from carriers. Aircraft can be launched from catapults in most conditions of wind and sea, but their recovery during a fleet action must necessarily be uncertain.
36. The main duties of the Fleet Air Arm are summarised below :
(i) Reconnaissance before and during an action.
(ii) Offensive action against enemy vessels.
(iii) Observation during an action.
(iv) Gunnery observation.
(v) Detection of submarines.
(vi) Laying smoke curtains.
37. The following types of aircraft are employed :
(i) Single-seater fighter.
(ii) Two-seater fighter.
(iii) Spotter-reconnaissance.
(iv) Torpedo-bomber.
38. The duties of the fleet single-seater fighter are similar to those of any other fighter. Their principal task is to deny the use of the air to enemy aircraft.
39. The two-seater fighter is at present in the experimental stage.
40. Spotter-reconnaissance aircraft are three-seaters with considerable range, equipped with appropriate facilities for navigation and communication. They are defensively armed, and are of a type suitable for carrying a moderate bomb load.
41. Torpedo-bombers are two-seater aircraft carrying a torpedo or its equivalent weight in bombs. They are defensively armed.
42. The aircraft described above are distributed throughout the fleet, the large majority being concentrated in the carriers. They are organised in flights of six. The distribution of the flights is such that any one carrier can provide aircraft for all the normal purposes of naval warfare.
43. The torpedo-bombers form a striking force which can be launched to the attack of enemy vessels at a moment selected by the commander-in-chief.
44. The commander-in-chief issues instructions for the employment of his aircraft in exactly the same way as for any other units of the fleet. The numerous problems inherent in the handling of aircraft make it necessary, however, for the detailed interpretation of his instructions to be left to the captains of carriers. For example, the departure and arrival of each flight of aircraft must be thought out in relation to the previous and subsequent movements of other aircraft. If this is not done, confusion will inevitably occur on the flying-decks and in the hangars.
45. Aircraft in ships other than carriers will be flown off by order of the senior officer of the squadron concerned. The time of launching these aircraft will be governed as much by the tactical needs of the naval action as by the air requirements of the moment.
Reconnaissance
46. Reconnaissance is of great importance in fleet operations. The speed and elusiveness of aircraft render them of the greatest value in the early stages of an action, and in normal circumstances they can obtain information of a more comprehensive nature than that secured by surface vessels. The latter invariably have to fight for any information of value, whereas it is very improbable that the enemy will be able to prevent preliminary reports of his strength and disposition being made by aircraft.
47. The commander-in-chief will be particularly anxious to get information of the enemy battle fleet. Early reports of its position, strength and course will be of the greatest value. Until these particulars are obtained, reconnaissance aircraft should not concern themselves with less important matters.
Offensive action against enemy vessels
48. The striking force of torpedo-bombers affords a means whereby the fleet can deliver a formidable blow from outside the range of its gun armament. In certain cases an attack so delivered may be the only means of bringing an enemy to action. If one or more of his battleships are damaged, a retreating enemy will almost certainly be forced to turn and fight.
49. The objective of the striking force will depend on the situation and on the plan of action of the commander-in-chief. The degree of concentration to be employed against the enemy ships selected for attack, and the correct moment for launching the attack, are matters requiring considerable judgment. For example, an attack which is launched too early will fail to find its objective, and many of the aircraft may be unable to get back to the carriers before running out of fuel. On the other hand, if the striking force is kept in hand for a decisive blow, hostile aircraft may arrive over the carriers and bomb the flights whilst they are ranged up on deck.
50. In certain circumstances it may be of the greatest importance to cripple the enemy's air activities at the earliest moment. In this case the striking force may be sent to attack the enemy carriers. It should be remembered, however, that the latter will probably be more distant than their battle fleet, and may therefore be more difficult to find.
51. There are three methods of using aircraft against capital ships :
(i) Torpedo attack.
(ii) High altitude bombing attack, with heavy armour-piercing bombs.
(iii) Low flying attack, with machine guns and light bombs.
52. The elements of torpedo attack are given in the Flying Training Manual, Part IV (Air Publication 1256, Chapter H). The following factors are of importance in making a successful torpedo attack :
(i) A good tactical plan skilfully executed.
(ii) A determination to come in to decisive range.
(iii) Surprise, including the use of clouds or other atmospheric features.
An attack on a fleet actively engaged will meet much less opposition than one in which the enemy is free to turn all his attentions to the attacking aircraft.
53. All torpedo and spotter-reconnaissance aircraft are fitted to carry bombs and an adequate number of bombs is held by all aircraft carriers for this purpose. The tactics of high bombing are included as part of the peace training of all reconnaissance and torpedo flights.
54. Low flying attacks with bombs and machine guns may be carried out by single-seater and two-seater fighters. This form of attack is suitable against the following objectives :
(i) Flying decks of carriers.
(ii) Bridges and torpedo tubes of destroyers.
(iii) Gun control positions.
55. Low flying attacks can be effectively made by fighters only. The value of such attacks against armoured ships has not yet been proved.
Observation during an action
56. Aircraft can provide the admiral with valuable information about the composition and movements of the enemy fleet immediately prior to and during the action.
Spotting for gunfire
57. Aircraft are used for spotting the fall of shot of the firing ship. Aircraft spotting suffers from several defects, and it will always be necessary to retain the normal spotting organisation of the firing ship. In the confusion and heat of an action, the observer may lose touch with the vessel for which he is spotting, or with the target at which the latter is firing. W/T communication may be interrupted, visibility may deteriorate, or an enemy fighter require driving off. Once an observer loses his grasp of the situation, he may not find it easy to resume his reports.
Detection of submarines
58. Aircraft are of considerable value against sub-marines. Their speed gives them the power of surprising a submarine on the surface, and of bombing it unobserved. Submarines will be reluctant to remain on the surface when aircraft are known to be in the vicinity. They will, therefore, find it difficult to pick up their targets or to get into suitable position for torpedo attack. The presence of aircraft does not disclose the position or movements of the fleet. Aircraft are capable to a limited extent of detecting submarines submerged. It is necessary for the observer to be nearly vertically overhead at the time, and much depends on the clearness of the water and the speed of the submarine. At periscope depth, however, the hull of a submarine is always liable to be seen by a vigilant aircraft.
59. The principal duty of aircraft employed on anti-submarine patrol is to force submarines to dive before the latter can sight and report the advance of the fleet, and also to report the presence of the submarines and attack them with bombs. A submarine on the surface should normally he attacked first and reported afterwards.
60. Aircraft can provide a close screen to watch the comparatively small area within which hostile sub-marines can deliver an effective torpedo attack on the fleet. The duty of such aircraft is to attack any sub-marine at sight. Aircraft may be employed in this manner on any occasion when a fleet or convoy is steaming through waters where enemy submarines are likely to he met. During an action it is unlikely that aircraft will be available for the purpose.
Laying smoke curtains
61. Aircraft can lay a smoke curtain rapidly and in positions which cannot be reached by surface vessels. The length and effectiveness of a smoke screen laid by aircraft is very dependent on the humidity of the air and on atmospheric conditions generally. Furthermore, accurate timing of the screen is essential. The employment of aircraft for this purpose should therefore be considered in relation both to the advantages it is expected to produce, and to possible alternative employment of the aircraft required.
62. Curtains may be laid on the following occasions :
(i) Offensively, to cover an attack by torpedo aircraft or destroyers. Smoke is of doubtful value in the former case, as it gives away the factor of surprise, which is of the utmost value in this form of attack.
(ii) Defensively, to cover vessels bombarding a shore objective, or to conceal the withdrawal of an inferior force. For the latter purpose, however, the use of funnel smoke is generally much more effective. On the other hand, for the protection of a bombarding force aircraft may provide the only suitable means of laying a screen.
Aircraft with detached forces
63. If carrier-borne aircraft are available for use with detached forces, they will be employed in much the same manner as if they were with the main fleet. Owing to the small number of aircraft available and the nature of the operations, it will generally happen that reconnaissance and anti-submarine patrols will be the most important of their functions.
64. In the absence of aircraft carriers, detached forces must rely on the aircraft they carry themselves. As explained before, these will usually consist of fighter or reconnaissance seaplanes mounted on catapults. Such aircraft are necessarily carried in exposed positions subject to the effects of climate, weather and gun-blast. Moreover, it is only in favourable conditions that they can be picked up undamaged after a flight. The sea must be smooth and the ship virtually stopped.
65. The presence of seaplane carriers, having no landing deck and usually carrying a small number of aircraft, may be of assistance to detached forces, but it is not usually considered economical to provide such vessels in time of peace.
66. Cruisers on the trade routes will usually be engaged in searching for enemy vessels interfering with commerce, and their aircraft will be employed mainly on reconnaissance duties.
