Royal Naval Air Service in the context of "History of the Royal Air Force"

The Royal Air Force (RAF) is the air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the First World War on 1 April 1918, on the merger of the Royal Flying Corps (RFC) and the Royal Naval Air Service (RNAS). Following the Allied victory over the Central Powers in 1918, the RAF emerged as the largest air force in the world at the time. Since its formation, the RAF has played a significant role in British military history. In particular, during the Second World War, the RAF defeated the German Luftwaffe's efforts to establish air superiority over England during the Battle of Britain, and played a key role in the Combined Bomber Offensive alongside the USAAF.

The RAF's mission is to support the objectives of the British Ministry of Defence (MOD), which are to "provide the capabilities needed to ensure the security and defence of the United Kingdom and overseas territories, including against terrorism; to support the Government's foreign policy objectives particularly in promoting international peace and security". The RAF describes its mission statement as "... [to provide] an agile, adaptable and capable Air Force that, person for person, is second to none, and that makes a decisive air power contribution in support of the UK Defence Mission". The mission statement is supported by the RAF's definition of air power, which guides its strategy. Air power is defined as "the ability to project power from the air and space to influence the behaviour of people or the course of events".

The Fleet Air Arm (FAA) is the naval aviation component of the United Kingdom's Royal Navy (RN). The FAA is one of five RN fighting arms. As of 2023 it is a primarily helicopter force, though also operating the F-35B Lightning II carrier-based stealth fighter jointly with the Royal Air Force.

The RAF was formed by the 1918 merger of the RN's Royal Naval Air Service with the British Army's Royal Flying Corps. The FAA did not come under the direct control of the Admiralty until mid-1939. During the Second World War, the FAA operated aircraft on ships as well as land-based aircraft that defended the Royal Navy's shore establishments and facilities.

The Royal Flying Corps (RFC) was the air arm of the British Army before and during the First World War until it merged with the Royal Naval Air Service on 1 April 1918 to form the Royal Air Force. During the early part of the war, the RFC supported the British Army by artillery co-operation and photographic reconnaissance. This work gradually led RFC pilots into aerial battles with German pilots and later in the war included the strafing of enemy infantry and emplacements, the bombing of German military airfields and later the strategic bombing of German industrial and transport facilities.

At the start of World War I the RFC, commanded by Brigadier-General Sir David Henderson, consisted of five squadrons – one observation balloon squadron (RFC No 1 Squadron) and four aeroplane squadrons. These were first used for aerial spotting on 13 September 1914 but only became efficient when they perfected the use of wireless communication at Aubers Ridge on 9 May 1915. Aerial photography was attempted during 1914, but again only became effective the next year. By 1918, photographic images could be taken from 15,000 feet and were interpreted by over 3,000 personnel. Parachutes were not available to pilots of heavier-than-air craft in the RFC – nor were they used by the RAF during the First World War – although the Calthrop Guardian Angel parachute (1916 model) was officially adopted just as the war ended. By this time parachutes had been used by balloonists for three years.

Flight lieutenant (Flt Lt or F/L) is a junior officer rank used by some air forces, with origins from the Royal Air Force. The rank originated in the Royal Naval Air Service (RNAS) in 1914. It fell into abeyance when the RNAS merged with the Royal Flying Corps during the First World War but was revived in 1919 in the post-war RAF. The rank is used by air forces of many countries that have historical British influence.

Flight lieutenant is immediately senior to flying officer and immediately below squadron leader. It is usually equivalent to the rank of lieutenant in the navy and of the rank of captain in other services.