Home > Browse tags > Aerial warfare and related concepts

Aerial warfare and related concepts

Entries are listed alphabetically. The first line (in bold) is the term used to describe the subject, which is also a hyperlink to every item in the IBCC Digital Archive described with that tag. The second line (in italics) contains alternative forms, such as spelling variants, abbreviations or colloquialisms. Each entry is supplemented with a definition, background information, applicability, and links to related concepts.

Indentations are used to denote a parent/child structure, in which the main entry is a broad category followed by sub-categories. This allows for users to either narrow or expand the focus of their searches.

aerial photograph
Used for: air-to-air photograph

Aerial photographs were used for three main purposes during the war: reconnaissance photographs were used to identify targets and evaluate damage whilst target photographs were taken by the individual attacking aircraft after dropping its bombs to assess their accuracy.   

reconnaissance photograph
Used for: recce

Aerial reconnaissance photographs were first widely used during World War One as an aid for Armies. The British Army retained responsibility for photographic reconnaissance until 1938 with the result that the RAF commenced World War Two with no specialised aerial photographic aircraft, equipment or techniques for interpretation. All combatant air forces in World War Two used reconnaissance photographs which had two main purposes; target identification before attacks and assessment of damage done after attacks. The RAF established Photographic Reconnaissance Units using Spitfires and Mosquitos. The Allies also used P-38s and P-51s. Photographs were analysed, often using stereoscopic images, at RAF Medmenham. Notable Allied reconnaissance photographic successes included the first identification of V-weapons at Peenemünde, the attacks on V-weapon launch sites in 1944 and the preparations for the Normandy campaign.

target photograph

Target photographs were taken thirty seconds after the bombs were released to show where they fell. The aircraft had to fly straight and level until the photo was taken. A flash was used for night-time operations. The photographs are often annotated with useful information that may include a reference number, the take-off station, the focal length, height, heading, time, target, bomb load, drop time in seconds, pilot’s rank and name, aircraft’s call sign and squadron. The photographs were used to check whether the aircraft had bombed the target effectively and encouraged crews to avoid ‘creep-back’ in which bombs were released short of the target. Some squadrons used target photographs as a competitive ‘bombing ladder’ to motivate crews to achieve more accurate bombing results.

Air Sea Rescue

In 1939 only a small fleet of rescue launches based at Coastal Command stations existed for the rescue of ditched aircrews; no aircraft were used until Lysanders were introduced in July 1940. In 1941 a Directorate of Air Sea Rescue Services was formed with senior RAF Coastal Command and Royal Navy Commanders. The service used high speed RAF and Navy launches coupled with dedicated air sea rescue aircraft including Ansons, Walruses, Lysanders, Hudsons, Spitfires and Warwicks aided by operational Sunderlands and Catalinas. In 1940 ditched aircrew stood little chance of being rescued but by 1944 their chances had improved to 60%. More than 13,000 lives were saved by Air Sea Rescue, of which 5658 were Allied aircrew.

Air Transport Auxiliary
Used for: ATA

A British wartime service tasked with the delivery of aircraft from factories to operational units: aircrew were civilians exempt from wartime service due to health, age and gender. Pilots from 30 countries served in the ATA of which 1152 were men and 166 were women. They delivered over 300,000 aircraft but were not trained for instrument flying or used radios so were subject bad weather risks. 149 ATA pilots were killed, including 20 women.

anti-aircraft fire
Used for: Flak, ak-ak, aa, A.A., archie, flaming onions

To fire weapons or artillery at an enemy aircraft. German anti-aircraft fire was commonly known as flak. Heavy anti-aircraft batteries comprised four or six 88 mm guns and light batteries had twelve 20 mm or 37 mm guns. Anti-aircraft batteries were either fixed in areas most frequently attacked or mobile to be moved to where needed most. Anti-aircraft batteries co-ordinated with searchlights. In Germany by 1945 there were over 20,000 anti-aircraft guns and over a million people were used manning them or searchlights.  

bale out
Used for: bail out

To jump out of an aircraft with a parachute in an emergency. Many Bomber Command aircrew lives were saved by the act of baling out from their aircraft. The Caterpillar Club is an association of people who have saved their lives by baling out and parachuting to safety from a disabled aircraft. By 1945 it had 34,000 members.

bomb disposal
Used for: defusing

A process whereby an explosive device is rendered safe. Not every bomb exploded on impact. Some were faulty and others had delayed action fuses. All unexploded bombs disrupted everyday life until they were dealt with. In Britain in 1940 bomb disposal teams were created as part of the Royal Engineers to deal with the increasing number of cases. Not only did they have to deal with unexploded German bombs but also Allied bombs at crash sites or that had been jettisoned. More than 750 British Bomb Disposal men were killed during the war.

bomb struck

Aircraft dropping a bomb on another over a target. Being bomb struck was always a risk in a bomber stream. To get as many aircraft as possible over the target is as little time as possible required aircraft to fly at different heights. Some aircraft, such as the Stirling, had lower operational ceiling heights than Halifaxes or Lancasters increasing their, albeit small, chances of being bomb struck.


The sustained aerial attack carried out by bombs dropped by aircraft. During the war the Luftwaffe was mainly used as a tactical air force and used bombing to support ground offensives. Following daylight bombing losses during the Battle of Britain in 1940 the Luftwaffe resorted to night bombing during the Blitz. Bomber Command initially tried daylight operations but switched to night attacks following heavy losses and was used mainly in a strategic bombing role. The Eighth United States Army Air Force operated from England from 1942 onwards in a daylight strategic bombing role which, together with Bomber Command, created the combined Allied strategic bombing offensive. During 1944 Bomber Command and the USAAF were also used in tactical roles in the preparation for and support of the Normandy campaign. Throughout the strategic bombing campaign there were tensions between those advocating area attacks and those who supported precision attacks on specific targets.

bombing up

To load an aircraft with bombs and/or incendiary devices. Bombing up was performed by armourers. Bombs were fitted with either nose or tail fuses depending on the type of detonation required. Bombs were taken to individual aircraft at their dispersals from the bomb dump on bomb trolleys pulled by tractors. Bombs were winched into the bomb bay and switches selected to reflect the order in which they were to be dropped. The bombs were armed shortly before take-off. Bombing up accidents did occasionally occur with aircraft destroyed and ground crew killed.

bouncing bomb
Used for: Highball bouncing bomb, Upkeep bouncing bomb

An explosive device designed to bounce to a target across water, then exploding in a fashion similar to a naval depth charge. See also: Eder Möhne and Sorpe operation (16–17 May 1943), 617 Squadron, Gibson, Guy Penrose (1918-1944), Wallis, Barnes Neville (1887-1979). The bouncing bomb was developed by Barnes Wallis for the Eder, Möhne and Sorpe operation. He showed that a bouncing bomb would skip across the water and roll down the face of the dam before exploding. The bomb, known as ‘Upkeep’ and weighing 9250 lb (4200 kgs), was carried under modified Lancasters by 617 Squadron. A smaller anti-ship bouncing bomb, known as ‘Highball’, weighed 1200 lb (544kgs) was to be carried by Mosquitos but never used operationally.


A meeting intended to secure a coordinated or unified effort before a bombing operation, especially an oral dissemination of information about weather, defences, and nature of the target. See also: debriefingPilots, navigators, bomb aimers and wireless operators often had their own specialised briefings before the target was revealed to all aircrew at the general briefing. Section leaders outlined topics such as the route, timings, secondary targets, bomb loads, wireless frequencies, defences, target indicators and taxiing procedures. Squadron and station commanders also spoke to boost morale.

Caterpillar club

The Caterpillar Club is an association for all people who have saved their lives by parachuting to safety from a disabled aircraft. As parachutes were originally made of silk it became known as ‘The Caterpillar Club’. Leslie Irvin of the Irvin Parachute Company agreed to give a certificate and a golden caterpillar badge to all those who were saved by parachutes. Other parachute manufacturers followed suit and by 1945 there were 34,000 members of the Caterpillar Club.

Cook’s tour
Used for: Thompson's tour, Baedecker's tour

A post-war, day-time sightseeing flight for ground personnel and/or civilians to view bombed targets. In the summer of 1945 aircrew took ground personnel on flights to Germany to show them the results of the strategic bombing campaign to which they had all contributed. Named after the holiday company six passengers at a time were flown across places like the Ruhr Valley. Aircrew could see at 500 feet in daylight what they hadn’t been able to see at night from 20,000 ft. Many were awed by the scale of destruction.


An accident in which aircraft uncontrollably hits the ground or a body of water. Aircraft crashes can occur for a variety of or combination of reasons. These include mechanical problems, weather, navigation error, pilot error, mid-air collisions, running out of fuel or in times of war by enemy action or being bomb struck. Crashes can occur through all stages of aircrew proficiency from initial training to experienced crews and from all stages of a flight from take-off to landing.

Take-off crash

Take off was always a time of increased risk for a Bomber Command aircraft. The aircraft was fully loaded with fuel and bombs and the engines were under maximum thrust. An engine failure could destabilise the aircraft. Some aircraft, such as the Stirling, were known to ‘swing’ on take-off causing extra difficulties for the pilot. When a take-off crash did occur it could put the runway out of action preventing the remaining aircraft from taking off.

crewing up

To join a crew, especially upon completion of basic training. At Operational Training Units the required number of each aircrew categories were assembled in a large room or hangar and simply told to ‘get on with it’. Crews would come together through a process of human chemistry and trust. Crews formed this way often came from different backgrounds and different countries. Although it seemed haphazard the process of crewing up often formed crews that remained closely bonded throughout their tour of operations and, for some, life-long friends.


To question aircrew about a completed operation. See also: briefing. On returning from a raid all aircrews were immediately debriefed to build up an immediate ‘picture’ of how the attack had gone and what had worked and what hadn’t. Usually given hot tea laced with rum whole crews were questioned by intelligence officers with a series of questions ranging from overall impressions of the attack to very specific questions regarding weather, marking, accuracy, navigation, night fighter and anti-aircraft defences and sightings of aircraft losses.


The aircrew knowingly make a controlled emergency landing on water. Many Bomber Command aircrew had to ditch in the sea when damage to the aircraft from operations prevented them from reaching land. Bombers were equipped with a dinghy and lifejackets, also known as Mae Wests. Aircraft about to ditch sent Morse code messages or released pigeons to alert the Air Sea Rescue services of their position. Crews who survived ditching became members of the Goldfish Club.


Escaping from a prisoner of war camp. RAF aircrew were provided with escape kits. Those shot down and captured became prisoners of war. Escape from captivity was achieved by some. Escapes ranged from the mass breakouts by tunnelling, such as ‘The Great Escape’ from Stalag Luft 3, to individual attempts to escape either from camps or whilst in transit. Escaped prisoners were sometimes able to contact Resistance organised escape lines. Most of the 2803 RAF aircrew that returned from Europe were evaders, the rest had escaped captivity.


Evading capture, usually after being shot down and baling out. RAF aircrew were provided with escape kits. Those shot down often hid during daylight and moved at night. Many RAF evaders made contact with organised escape lines; the Comet and Pat Escape Lines linked Belgium and northern France through to Spain and Gibraltar whilst the Shelburne Line took evaders to the Brittany Coast. Most of the 2803 RAF aircrew that returned from Europe were evaders, the rest had escaped captivity. Many Resistance members lost their lives helping Allied evaders.

forced landing
Used for: prang, write-off, crash landing

Abruptly bringing an aircraft to the ground or the surface of water in an emergency with elements of a normal landing outside the pilot’s control. Reasons for forced landing can include mechanical problems, weather, running out of fuel or damage to the aircraft from mid air collisions or, in times of war, from enemy action or being bomb struck.


To resupply an aircraft with fuel. Bomber Command aircraft were fuelled at dispersal by ground crew using petrol bowsers. Ground crews often formed an idea of the likely target for an operation by the amount of fuel being used. In-flight refuelling trials had commenced for the Tiger Force before that was abandoned. Flight engineers were responsible for managing the fuel systems during flight.

Gee and Gee-H
Used for: Gee H, G-H, GH

Hyperbolic navigation system used operationally by Bomber Command. The Gee cathode ray receiver in the aircraft measured the radio wave time differences between one ‘master’ and two ‘slave’ widely spaced ground transmitters. Navigators plotted the readings onto special charts with overlapping hyperbolas, each representing a master-slave pair. Gee was introduced operationally in 1942. However the system was limited in range by the curvature of the earth, became more inaccurate with distance and was susceptible to German jamming. In a further development Gee-H was developed as a blind bombing system that could be used by a number of aircraft at the same time. Gee-H came into operational use in July 1944 and was used especially by 3 Group which could then operate independently from the Pathfinders of 8 Group.  During daylight operations non Gee-H aircraft formatted on Gee-H leaders and dropped bombs at the same time. For night attacks Gee-H aircraft acted as markers.


The Gneisenau was a battleship in the German Kriegsmarine. Gneisenau entered service in 1938 and was 771 ft. (235 m) long, displaced over 38,000 tons, had nine 11 inch (28 cm) guns and a speed of 31 knots (36 mph, 57 kph). Gneisenau and its sister ship the Scharnhorst operated together in the Atlantic and the Norway campaigns when they sunk the aircraft carrier HMS Glorious. A Bomber Command attack on Kiel docks in February 1942 damaged Gneisenau sufficiently to end its active service.

Goldfish Club

Association of aircrew who were rescued from the sea after ditching and survived by using either a rubber dinghy or their lifejacket, also known as a Mae West. The company that made the dinghies and lifejackets formed the Goldfish Club in 1942 to allow ditched aircrew to share their mutual experiences. By 1945 the club had over 9,000 members.

Grand Slam
Used for: 22000lb bomb, earthquake bomb

A bomb deployed against massive and hardened structures. The 22,000 lb (9980 kgs) Grand Slam bomb was 25 ft. 5 in (7.5 m) long and the most powerful non-nuclear bomb used in the Second World War. It was designed by Barnes Wallis to explode at depth creating an earthquake effect. It could also penetrate thick concrete. Targets including railway viaducts and submarine pens. 617 Squadron was the only squadron to use them using specially modified Lancasters. 41 Grand Slams were dropped during March and April 1945.


An imaginary mischievous creature that causes faults in aircraft or other machinery, frequently used as generic synonym for difficult-to-track-down, recurring malfunction. First identified during the 1920s the mythical creatures became a popular source of blame for things-that-went-wrong in the RAF during World War Two. Gremlins became part of the folklore of the RAF and were expressed in poetry and art where they were often depicted as goblins, imps, elves or sprites with some painted as nose-art on bombers. Gremlins became more widely known beyond the RAF after 1943 when Roald Dahl collaborated with Walt Disney and wrote a book about them which became popular.

Guinea Pig Club

Social club and mutual support network for British and allied aircrew injured by burns and operated on by Archibald McIndoe at East Grinstead in the Queen Victoria Hospital using pioneering plastic surgery. A group of patients formed the Guinea Pig Club in light of the experimental methods. Initially there were 39 patients, mainly fighter pilots. By 1944-45 80% of patients were from Bomber Command and membership reached 649. Sir Archibald McIndoe also encouraged patients to socialise normally with local people.

Used for: BN, Blind Navigation

Airborne ground scanning radar system used operationally by Bomber Command from January 1943 to aid navigation and bombing. A rotating dish aerial was located in a housing beneath the fuselage and returning signals ‘painted’ a picture of the landscape below on the navigator’s cathode ray tube. Although the system could not be jammed the Germans could detect H2S signals enabling the whole main force to be tracked and individual aircraft to be attacked by night fighters.

incendiary device
Used for: firebomb

A bomb designed to start a fire. Incendiary devices were used by all combatant air forces during World War Two. The 4 lb (2 kg) magnesium incendiary bomb was one of the main weapons used by Bomber Command during World War Two and 80 million of them were dropped. Initially they were packed into small bomb containers but these were difficult to aim as the incendiaries scattered downwind. From 1943 incendiaries were packed into 500 lb (227 kg), 750 lb (341 kg) or 1000 lb (454 kg) cluster projectiles. A typical 14,000 lb Lancaster bomb load comprised two-thirds high explosive and one-third incendiary, although higher proportions of incendiaries were also used.

killed in action
Used for: killed in air operations, KAO, KIA

The death of a combatant at the hands of hostile forces. The term is often abbreviated to KIA. During World War Two of the almost 58,000 people who died whilst serving with or supporting Bomber Command more than 47,000 were killed in action or missing, presumed dead.

lack of moral fibre
Used for: LMF

A punitive designation used by the Royal Air Force during the Second World War to stigmatise aircrew who refused or were unable to fly operations. The term ‘Lack of Moral Fibre’ (LMF) came into use in March 1940 when the RAF considered what to do with a member of aircrew who, for non physical medical reasons, refused to fly or otherwise ‘lost the confidence of his Commanding Officer’. Aircrew had volunteered to fly but couldn’t volunteer not to. A case depended on how much operational stress the man had been subjected to and his predisposition to stress. Accordingly, although cases were referred to Medical Officers and even neuropsychiatry specialists, the Commanding Officer was always involved and the classification of LMF was not a medical diagnosis. Cases of LMF were rare and resulted in loss of the flying badge and reduction in rank. Individuals were often removed quickly to avoid the perceived risk of contagion to squadron morale. The threat of being stigmatised as LMF was, in effect, used as a euphemism for cowardice and therefore a deterrent.


The extrajudicial killing by a group, often used to denote public executions by a mob in order to punish aircrew who baled out on enemy territory. Particularly from 1943 Nazi leadership speeches and circulars created the conditions for such acts in Germany and occupied territories. It has been estimated that one-in-twenty captured RAF aircrew and one-in-eighty captured American aircrew were either shot, hung, beaten or pushed to their deaths. Some of those responsible, whether civilian or military, were later tried for war crimes.

master bomber
Used  for: controller, director, MC

An experienced pilot tasked to coordinate the combined effort of aircraft over the target. The master bomber stayed in the target area for the entire attack and directed the Pathfinder marking and main force bombing, issuing encouragement, instructions and corrections by radio. The first use of a master bomber involving the main force was a 5 Group operation by 60 aircraft in June 1943. In August 1943 a master bomber controlled a full scale Bomber Command operation for the first time for the attack on Peenemünde. The use of a master bomber was not always successful. Problems could occur due to poor radio communications, weather, strength of defences and type of target.

mid-air collision

An accident in which two or more aircraft come into contact during flight. The risk of a Bomber Command mid-air collision was always present in crowded air spaces such as the landing circuit and over the target. The bomber stream concept of putting as many aircraft as possible over the target is as little time as possible did increase the risk of mid-air collisions even though statistically it was small. Aircrews were briefed to be accurate with timings and heights in order to minimise the risk although collisions did still occur.

mine laying
Used for: gardening

To deploy sea mines carried out by aircraft. Bomber Command dropped thousands of mines in shipping lanes throughout the war. Aerial mines were referred to as ‘vegetables’ and the operational dropping of mines was referred to as ‘sowing’ while the mining operations were referred to as ‘gardening’. Aircraft mines were cylindrical, approximately 17 inches (43 cms) in diameter and 9 feet (3 m) long. The weight averaged 1,500 lbs. (680 kg) of which 750 lbs. (340 kg) was explosive. A small parachute attached at the end would facilitate vertical entry into the water. The mine would then sink to the sea floor awaiting non-contact detonation by acoustic sound signature, magnetic field signature or period delay mechanisms. Mines sunk almost 500 ships and approximately 400 Bomber Command aircraft failed to return from ‘Gardening’ operations.

missing in action
Used for: MIA

Bomber Command aircrew who did not return from operations were initially categorised as ‘missing in action’. Subsequently they could be re-categorised as ‘killed in action’, ‘prisoner of war’, ‘missing-death presumed’ or simply remain missing. In December 1944 the RAF Missing Research and Enquiry Service was established to try to trace all those still missing in action and their work continued until September 1949 with remaining searches subsequently carried out by the casualty branch of the Air Ministry..

Morse-keyed wireless telegraphy

Sending and receiving messages via a Morse key and a radio telegraphy link using different combinations of dots and dashes for different letters of the alphabet.  Bomber Command aircrew included a wireless operator to maintain communications links with the aircraft. During World War Two morse-keyed wireless telegraphy, often using secret codes, was a vital communication tool in all armed forces, including the Special Operations Executive.

Navy, Army and Air Force Institutes
Used for: NAAFI

A company running recreational establishments needed by the British Armed Forces, and to sell goods to servicemen and their families. The Navy, Army & Air Force Institute, universally known as the NAAFI, started trading in 1921 as a not-for-profit organisation. It expanded overseas and, at its peak during World War Two, it had 110,000 employees and nearly 10,000 trading outlets. It also controlled the Entertainment National Services Association known as ENSA, the forces entertainment organisation.

nose art

Nose art is a painting or design on the front of the fuselage of a military aircraft. The number of operations each aircraft completed or how many enemy aircraft it had shot down was recorded by painting symbols below the cockpit. Operations to Italy were sometimes symbolised by the depiction of an ice-cream cone. Some aircraft were given their own character, name or a mascot, and painted with nose art. As a form of folk art, they were painted by an artistic member of the aircrew or ground crew with comical cartoons, risqué pin ups or quotes. Nose art expressed the individuality of a particular aircraft and could become a good-luck charm.


Aerial blind bombing system based on radio transponder technology. A ground station, known as ‘cat,’ transmitted radar pulses which triggered transponders in the aircraft to send back pulses. The aircraft navigated along an arc from the ‘cat’ station, controlled by Morse dots and dashes. Signals from another station known as ‘mouse’ controlled the release point. Because Oboe could only control one aircraft every 10 minutes and was limited by the curvature of the earth it was almost exclusively used by Pathfinder and Mosquitos.


Squadrons tasked to locate and accurately drop target indicators, to increase the accuracy of the main bomber force. The Pathfinder Force was formed in August 1942 under the command of Donald Bennett. The Pathfinders flew ahead of and guided the main force by using route markers and target indicators. Master bombers directed attacks. The Pathfinder Force became 8 Group in January 1943. Aircrews volunteered to be Pathfinders, flew tours of 45 operations, had their own badge and had a temporary promotion and associated pay increase.

perception of bombing war

Judgement about the bombing war, legitimacy of targets, moral dilemmas etc. The bombing campaigns of World War Two, whether by the Axis Powers or by the Allies have been controversial, both during and since the war. The ethics and morality of the campaigns continue to be debated. Perceptions will always be subjective and differ depending on the particular perspective from which the bombing campaigns are viewed or the questions asked. Such perspectives and questions include participant or victim, area or precision, strategic or tactical, gain versus cost and ends versus means.

Photographic Reconnaissance Unit
Used for: PRU

A unit tasked with reconnaissance for a military or strategic purpose that is conducted by using reconnaissance aircraft. RAF Photographic Reconnaissance Units (PRUs) were first established in 1939 under Fighter Command control but from 1940 they were based at RAF Benson under Coastal Command control. Mainly flying unarmed Spitfires and, from 1942, Mosquitos PRU aircraft depended on speed and altitude to avoid enemy fighters with most sorties being flown above 25,000 ft. (7620 m) and some as high as 44,000 ft. (13,400 m). Reconnaissance photographs were interpreted at RAF Medmenham which included the Bomber Command Damage Assessment Section.


To award servicemen a higher rank because of service length or deeds in combat; includes commissioning. There were four types of promotion in the RAF during World War Two. Substantive promotion was limited to officers with permanent commissions. Time-based promotions saw pilot officers promoted to flying officers after 6 months and, 18 months later, to flight lieutenants. Temporary promotions were also possible, such as Pathfinder aircrews. Acting rank promotions were made pending the arrival of an officer of the required substantive rank.

Used for: Nickel, Nickels

Information used to promote a political cause, or a specific point of view, especially when involving dropping of printed material on enemy territory. During the early months of World War Two Bomber Command were not allowed to bomb civilian areas but they did drop propaganda leaflets over occupied Europe and Germany. Theses raids were known as ‘nickel’ raids. Whilst their military value has been questioned these sorties did provide aircrews with experience of operating and navigating by night.

Used for: Radio Detecting and Ranging

A detection system that uses radio waves to determine the range, angle, or velocity of objects. The reflection of radio waves from objects is the basis of what was originally called ‘radio detection and ranging’, now known as radar. Robert Watson-Watt led the British development of radar and by 1940 a chain of radar stations proved crucial during the Battle of Britain. Radar systems developed during the war included the Oboe blind bombing system and the H2S navigation aid both used by Bomber Command. Airborne radar was used by both Luftwaffe and RAF night fighters. Radar was also used to control searchlights and anti-aircraft fire.

Royal Observer Corps
Used for: ROC

A British civil defence organisation intended for the visual detection, identification, tracking and reporting of aircraft over Great Britain. The Observer Corps was under RAF control but comprised civilian volunteers who manned observation posts and reported in to command centres. During the 1940 Battle of Britain the Observer Corps were the only means of tracking Luftwaffe aircraft once they had crossed the coastal radar stations. Their reports were a vital part of the Dowding System to direct Fighter Command. King George VI conferred the ‘Royal’ prefix to the Observer Corps in 1941.


The Scharnhorst was a battleship in the German Kriegsmarine. Scharnhorst entered service in 1939 and was 771 ft. (235 m) long, displaced over 38,000 tons, had nine 11 inch (28 cm) guns and a speed of 31 knots (36 mph, 57 kph). Scharnhorst and its sister ship the Gneisenau operated together in the Atlantic and the Norway campaigns when they sunk the aircraft carrier HMS Glorious. In December 1943 Scharnhorst was sunk by the Royal Navy.

shot down

To cause to fall by enemy action, e.g. night fighters or anti aircraft fire. Bomber Command lost just under 9000 aircraft in World War Two, many of which were shot down. They were either hit by anti-aircraft fire or by Luftwaffe fighters. Some aircrew survived by baling out and, if over occupied territory, either became evaders or prisoners of war.

Special Operations Executive
Used for: SOE

A British organisation tasked to conduct espionage, sabotage and reconnaissance in occupied Europe against the Axis powers, and to aid local resistance movements. The Special Operations Executive (SOE) was formed in 1940 and volunteers came from different countries and from both military and civilian backgrounds. Agents were trained in combat and Morse code skills before mainly being dropped by parachute or landed by aircraft from RAF Tempsford. Many SOE agents, including some women, lost their lives.


Attacking ground targets from low-flying aircraft using aircraft-mounted automatic weapons. When the Allies gained air superiority in the European theatre, strafing became widespread: trains, isolated vehicles, troop concentrations, watercrafts and other targets of opportunity were attacked in a vast number of small-scale actions. Civilian informants describe being strafed as one of the most traumatic wartime experiences. Unlike bombing, no warning was usually given and strafing could take place even where people feel they were safe owing to the obvious lack of any relevant target nearby. Additionally, survivors frequently came to see strafing as both personal and hatred-driven because it was carried out at close range.


As an underwater weapon of war, the German Kriegsmarine submarines (U-boats) posed a major threat during World War Two, in particular to the surface vessels of the Royal Navy and the merchant ships in the North Atlantic and Russian convoys. The Royal Navy and RAF Coastal Command worked closely together in overcoming the submarine threat and Coastal Command aircraft were involved in sinking over 200 German submarines. Bomber Command also attacked submarine construction yards and pens.

Used for: 12000lb bomb, earthquake bomb

A bomb deployed against massive and hardened structures. The Tallboy bomb was designed by Barnes Wallis to explode at depth creating an earthquake effect. It could also penetrate thick concrete. Targets included submarine pens, V-weapon sites, railways tunnels and viaducts. The Tirpitz and Lützow capital ships were also sunk. Tallboys required specially modified Lancasters and were used by 617 Squadron from June 1944 and, later, by 9 Squadron. Tallboys were 21 ft. (6.5 m) long and weighed 12,000 lb (5440 kgs). 877 Tallboys were dropped on operations including those that missed or were jettisoned: 578 by 617 Squadron and 299 by 9 Squadron.

target indicator
Used for: marker; TI; marker flare; flares; Christmas tree; Weihnachtsbäume

Target indicators were devices developed for Bomber Command and used by the Pathfinders to mark the target aiming point for the main force. As the raid progressed the target could be remarked using distinct colours, which could be red, green or yellow. The target indicators were usually 250 lb (113 kg) but 1,000 lb (454 kg) and larger were developed. When dropped from the aircraft the casing of the target indicator would fragment at the selected height and pyrotechnic candles would be ejected and burn for about three minutes. There was an extended burn variant that lasted seven minutes at a lesser intensity.


The Tirpitz was a battleship in the German Kriegsmarine. It entered service in 1941 and was 824 ft. (251 m) long, displaced over 50,000 tons, had eight 15 inch (38 cm) guns and a speed of 30 knots (35 mph, 56 kph). The Tirpitz was based in Norway from where it was feared it would be used against Allied Atlantic convoys. The Tirpitz was attacked on a number of occasions including by mini-submarines, the Fleet Air Arm and by Bomber Command before being sunk in November 1944 in Operation Catechism by 617 Squadron and 9 Squadron both using Tallboy bombs.


A process intended to establish and improve the capabilities of military personnel to fulfil their respective roles. All new Bomber Command recruits attended basic training at Initial Training Wings. Pilots, observers and navigators then attended Elementary and Service Flying Training Schools. Many of these were located in Canada, Australia, South Africa, South Rhodesia (now Zimbabwe) as part of the British Commonwealth Air Training Plan, or Empire Air Training Scheme. Wireless operators, air gunners, bomb aimers and flight engineers received specialist training, the latter at RAF St Athan. Most crew members were brought together at Operational Training Units for the process of crewing up. Flight engineers joined the crews at Heavy Conversion Units before the crew moved to operational squadrons. Later in the war Lancaster Finishing Schools completed the training process.

Initial Training Wing
Used for: ITW

More than 35 Initial Training Wings (ITW) were established around the UK during World War Two to provide basic service training for new aircrew recruits. Many ITWs were located in seaside resorts using requisitioned hotels including RAF Bridlington, RAF Paignton and RAF Torquay. Training courses lasted 8 – 12 weeks. Classroom courses included flight theory, airmanship, navigation, meteorology, maths, Morse code and aircraft recognition; the pass mark was 80%. Four hours a day were also spent on drill and physical training.

Flying Training School
Used for: FTS

333 Flying Training Schools were used during World War Two, just under half of which were in the UK and the rest overseas as part of the Empire Air Training Scheme, notably in Canada, Australia and Southern Africa. Pilots received their basic training at Elementary Flying Training Schools (EFTS). Aircraft used were Tiger Moths, Magisters, Stearmans and Cornells. Graduating to Service Flying Training Schools (SFTS) pilots were subsequently trained on more powerful Yales and Harvards.

Air Observers School
Used for: AOS

Air Observers Schools (AOS) were established to provide specialist training for observers and navigators. UK based AOSs include RAF Bishops Court, RAF Dumfries, RAF Halfpenny Green, RAF Millom and RAF Wigtown. Others were based overseas as part of the Empire Air Training Scheme. Aircraft types used included Ansons, Bothas and Whitleys.

Bombing and Gunnery School
Used for: BAGS

Bombing and Gunnery Schools (BAGS) were established to provide training for observers, navigators, bomb aimers and air gunners as part of their overall training. UK based BAGSs include RAF Dumfries, RAF Millom and RAF West Freugh. Other schools were established overseas as part of the Empire Air Training Scheme. Aircraft used included Battles, Bolingbrokes, Ansons and Bothas.

Air Gunnery School
Used for AGS

Air Gunnery Schools (AGS) were established to provide specialist training for air gunners. UK based AGSs include RAF Barrow in Furness, RAF Bishops Court, RAF Evanton, RAF Llandwrog, RAF Pembrey and RAF Stormy Down. Other schools were established overseas as part of the Empire Air Training Scheme. Aircraft used included Lysanders, Defiants, Ansons, Blenheims, Wellingtons, Battles and Whitleys.

Advanced Flying Unit
Used for: AFU

Advanced Flying Units were established as an intermediate stage of training between Flying Training Schools and Operational Training Units. Pilots destined for Bomber Command were introduced to multi-engined aircraft at AFUs, typically Oxfords and Ansons. Navigators and bomb aimers also went through their own AFUs using Blenheims, Bothas, Oxfords and Ansons. UK based AFUs include RAF Bishops Court, RAF Dumfries, RAF Hixon, RAF Millom, RAF Ossington, RAF Shawbury and RAF West Freugh. Other AFUs were established overseas as part of the Empire Air Training Scheme.

Operational Training Unit
Used for: OTU

A training establishment that prepared aircrew for operations on a particular type or types of aircraft or roles. Following their individual specific trade training programmes aircrew members came together at Operational Training Units to form crews and to learn how to work together. After crewing up they embarked on an 80 hours, 10 week programme. Exercises included night time navigation, bomb aiming and fighter affiliation. The combination of inexperienced crews often flying ex-operational aircraft resulted in high accident rates. OTUs were initially controlled by 6 Group and 7 Group but from May 1942 by 91, 92 and 93 Groups.

10 OTU
11 OTU
12 OTU
13 OTU
14 OTU
15 OTU
16 OTU
17 OTU
18 OTU
19 OTU
20 OTU
21 OTU
22 OTU
23 OTU
24 OTU
25 OTU
26 OTU
27 OTU
28 OTU
29 OTU
30 OTU
81 OTU
82 OTU
83 OTU
84 OTU
85 OTU
86 OTU

Heavy Conversion Unit
Used for: HCU

A training unit that prepared aircrew for operations on heavy bombers. When four-engined bombers came into service training problems became apparent in that aircrews entering squadrons had no experience of such aircraft. Crew composition was also changing with the introduction of flight engineers coupled with second pilots no longer being needed. Heavy Conversion Units (HCUs) were created in each Bomber Command group with courses lasting five weeks plus squadron conversion flights. From October 1942 squadron conversion flights were discontinued with all final training being done in HCUs or Lancaster Finishing Schools. 7 Group controlled HCUs from September 1944.

1651 HCU
1652 HCU
1653 HCU
1654 HCU
1656 HCU
1657 HCU
1658 HCU
1659 HCU
1660 HCU
1661 HCU
1662 HCU
1663 HCU
1664 HCU
1665 HCU
1666 HCU
1667 HCU
1668 HCU
1669 HCU
1674 HCU
1678 HCU
1679 HCU
1699 HCU
1957 HCU
1958 HCU
1974 HCU

Lancaster Finishing School
Used for: LFS

A training establishment tasked to provide additional Lancaster experience to aircrews who had finished their training at a Heavy Conversion Union prior to posting to an operational squadron. The shortage of Lancasters for training in mid-1943 led to the formation of Lancaster Finishing Schools (LFS). These enabled crews to complete the last 10 hours of their training on the aircraft in which they were to fly operationally. 1 Group LFS formed at RAF Hemswell, 3 Group LFS at RAF Feltwell, 5 Group LFS at RAF Syerston and 6 Group LFS at RAF Ossington.

physical training
Used for: PT

Activities intended to achieve the ability to perform service activities. See also sport. The Royal Air Force School of Physical Training was established in 1918 and was responsible for training physical instructors across the service. Informal activities on squadrons and stations included football, cricket, rugby and cross-country running. Physical training was a very important activity in prisoner of war camps for keeping fit and maintaining morale.


The German V-Weapons were used operationally 1944-1945. The V-1 was a flying bomb powered by a pulse-jet, launched from ramps with a range of 160 miles (250 kms). The V-2 was a liquid propelled rocket with a range of 200 miles (320 kms). The V-3 was a multi-barrel gun with each barrel 430 ft. long (130 m) and a range of 100 miles (165 km); it never became operational. The V-1 and V-2 weapons were being developed at Peenemünde which was attacked by Bomber Command in August 1943 delaying their deployment. Production was moved to underground facilities at Nordhausen. 20,000 forced labourers died during their production, more than the number of people killed by V-weapon attacks. V-weapons were used to attack targets in England, Belgium, France, Netherlands and even Germany in areas by then taken by the Allies.

Used for: V1, V-1 bomb, buzz bomb, flying bomb, FZG-76, V-1 rocket, Vergeltungswaffe 1, doodlebug, Kirschkern, Maikäfer

The V-1 was a flying bomb powered by a pulse-jet and launched from ramps. It had an explosive charge of 1870 lb (850 kgs), speed of 400 mph (640 kph) and a range of 160 miles (250 kms). The V-1 was being developed at Peenemünde which was attacked by Bomber Command in August 1943 delaying their deployment. Almost 30,000 V-1s were built. Launched from the Pas-de-Calais area in France the first V-1 landed in Britain in June 1944 and the last in March 1945. Despite sustained Bomber Command attacks on launch sites over 9200 were launched at England, at times 100 a day. Just under 2500 reached London, killing over 6000 people. 1800 V-1s were shot down by anti-aircraft fire, 1800 brought down by RAF fighters and 200-300 by barrage balloons. Almost 2,500 V-1 attacks were also made against targets in Belgium.

Used for: V2, V-2, V-2 rocket, Aggregat-4, Vergeltungswaffe 2

The V-2 was a liquid propelled rocket 46 ft. (14 m) long with a warhead of 2200 lb (1000 kg), a speed of 3580 mph (5760 kph) and a range of 200 miles (320 kms). It reached an altitude of 55 miles (88 kms) on a long range trajectory. The V-2 was being developed at Peenemünde which was attacked by Bomber Command in August 1943 delaying their deployment. 5200 V-2s were built. Initially they were to be launched from fixed sites at Watten and Wizernes but these were disabled in June 1944 by Tallboys dropped by 617 Squadron. Mobile launching sites for V-2s were subsequently used. About 1500 V-2s were launched against England, the first in September 1944 and the last in March 1945 in total killing about 2800 people. 1700 V-2s were also launched against Belgium, 76 against France, 19 against the Netherlands and 11 against Allied troops at Remagen in Germany.

Used for: V3, London cannon, Vergeltungswaffe 3, Hochdruckpumpe, HDP, Fleißiges Lieschen, Busy Lizzie

The V-3 weapon was a multi-barrel long range gun battery buried underground at Mimoyecques in the Pas-de-Calais area. Each barrel was 430 ft. long (130 m) and secondary charges boosted the fin stabilised shell’s velocity as it proceed along the smooth-bore barrel. It had a range of 100 miles (165 km) and was aimed at London. Originally it was intended to have ten groups of five barrels but this was reduced to five groups of five barrels supported by a complex of underground tunnels. The guns were to fire a projected rate of up to 300 shells per hour through gaps in the only structure visible on the surface which was a concrete slab measuring 70 m x 30 m. 617 Squadron successfully attacked the site on 6 July 1944 with Tallboys and the V-3 site never became operational.

Used for: chaff

Radar countermeasure consisting of thin pieces of aluminium swamping the screen with multiple returns. See also: radar. By 1942 the German defences had developed radar guided searchlights, anti-aircraft guns and night fighters. In early 1942 research indicated that aluminium foil or paper with an aluminium coating with specific dimensions dropped from aircraft disrupted radar displays. It was code-named Window. German radar only used three main frequencies enabling the dimensions and quantities of Window required to be calculated. Window was first used in the bombing of Hamburg in July 1943 and proved effective. Aluminium foil is still used to degrade radar.