Lympne Airport /ˈlɪm/ was a military and later civil airfield (IATA: LYM, ICAO: EGMK), at Lympne, Kent, United Kingdom, which operated from 1916 to 1984. The airfield was built out of necessity in the First World War. During the First World War RFC Lympne was originally an acceptance point for aircraft being delivered to, and returning from, France but was later designated as a First Class Landing Ground, RAF Lympne. It became a civil airfield in 1919 and saw the operation of early air mail services after the 1918 armistice. It was one of the first four airfields in the United Kingdom with customs facilities.

Lympne was also involved in the evolution of air traffic control, with facilities developing and improving during the 1920s and 1930s. A number of record-breaking flights originated or ended at Lympne. During the 1920s Lympne was the venue for the Lympne light aircraft trials from which a number of aircraft types entered production. Air racing was also held at Lympne.

Just before the Second World War, Lympne was requisitioned by the Fleet Air Arm. It was named HMS Buzzard and renamed HMS Daedalus II three months later, before being transferred to the Royal Air Force in May 1940. During the war Lympne was a front-line fighter base, RAF Lympne. It was heavily bombed during the Battle of Britain in 1940 and put out of action for a number of weeks. It was too close to the coast to be used as a squadron base, but squadrons were detached there on a day-to-day basis. Lympne was also to have been the landing place for a German aircraft used in a plot to kidnap Adolf Hitler, with preparations made by the Royal Air Force for his arrival.

Lympne returned to civilian use on 1 January 1946. In 1948, the first air ferry service was inaugurated at Lympne by Silver City Airways. Problems with waterlogging of the grass runway and the refusal of the Ministry of Transport and Civil Aviation to upgrade the airfield led to Silver City transferring operations to Lydd (Ferryfield) in 1954. By 1956, the airport's ownership had passed to Eric Rylands Ltd, the Skyways holding company. Skyways operated a coach-air service between London and Paris, flying passengers from Lympne to Beauvais. This service operated until 1974 (1955–1958: the original Skyways; 1958–1971: Skyways Coach-Air; 1971–1972: Skyways International; 1972–1974: Dan-Air Skyways). Following the cessation of commercial operations in October 1974, Lympne continued to be used as a General Aviation airfield until about 1984. The site is now an industrial estate.

Work began on creating a landing ground at Folks Wood, Lympne, in the autumn of 1915. This site soon proved unsuitable and another site was sought. Lympne was established in March 1916 as an Emergency Landing Ground for the Royal Flying Corps (RFC) home defence fighters defending London against Zeppelins and Gothas. No. 1 Advanced School of Air Gunnery operated from Lympne during January and February 1917. In January 1917 it was designated as No. 8 Aircraft Acceptance Park for delivery of aircraft to, and reception from, France. On 25 May 1917 Lympne was bombed by Gotha G.IV bombers of Kagohl 3 who dropped 19 bombs on the airfield.

In 1918, Lympne was designated a First Class Landing Ground and the Day and Night Bombing Observation School was formed here in May. The RFC and the Royal Naval Air Service (RNAS) were merged to form the Royal Air Force (RAF) in April 1918. From 17 July 1919, No. 120 Squadron RAF flew air mail services between Lympne and Cologne, Germany, using de Havilland DH.9 aircraft fitted with Beardmore Halford Pullinger engines. This service ended on 1 September 1919 when 120 squadron moved to RAF Hawkinge. Hawkinge and Lympne lay within a few miles of each other and as the Air Ministry could not justify keeping the two bases open following the end of the war, they decided to retain Hawkinge. In August 1919 the RAF moved out of Lympne and it was turned over to civilian use, although 120 Squadron did not depart until 21 October.

In May 1919, Lympne was one of the first four customs and excise "Appointed Aerodromes" in the United Kingdom; along with Hadleigh in Suffolk, Hounslow Heath in Middlesex and New Holland in Lincolnshire. Although Lympne had a customs clearance point there was no permanent customs officer there; a telephone call to Folkestone Harbour was needed to clear customs. On 1 May the ban on civilian flying was lifted and a Sopwith Gnu was flown from Hounslow Heath to Lympne carrying a cargo of newspapers during that first day. In September, Sir Philip Sassoon purchased an Avro aircraft in which he commuted between London and his Lympne residence. In October the Air Ministry announced that searchlights would temporarily be displayed to assist aircraft to find certain airfields. Lympne was to be identified by three searchlights arranged in a triangle, their beams shining vertically. In November a Notice to Airmen was issued advising that radio telephony was in use at Hounslow Heath and Lympne, using the 900-metre wavelength. The practice of using the aircraft registration as a callsign was instigated. In December 1919 two Westland Limousine aircraft bound for the Paris Aero Show were delayed at Lympne by fog. Conditions later improved so that both aircraft were able to fly to Le Bourget, where G-EAJL was dismantled and transported to the Grand Palais where it was exhibited to the public. The other aircraft remained at Le Bourget where it gave pleasure and demonstration flights.

The North Sea Aerial and General Transport Co. used a Blackburn Kangaroo on its short-lived Leeds-Lympne-Amsterdam service from 6 March 1920. The customs facilities at New Holland had been withdrawn on 28 January, necessitating the roundabout route. It was estimated that the extra costs involved in taking this route amounted to one-third of the total costs. Flight called for customs facilities to be established to enable direct flights to be made from the north of England to the continent. Starting from 2 August, hourly weather forecasts were broadcast from Lympne and other airfields. A system of ground signals advising pilots of the weather conditions at Biggin Hill and Croydon was also introduced about this time. During August, Aircraft Transport and Travel took over air mail flights, using DH.9A aircraft. In November a Notice to Airmen was released announcing that searchlights would be in use at Lympne for two hours after sunset to assist pilots in landing their aircraft. Arrangements could be made in advance for this facility to be made available after the notified hours. In December, it was announced that an "aerial lighthouse" was to be installed at Lympne as the one installed at Croydon had proved to be of benefit to pilots arriving after dark.