Douglas A-1 Skyraider AD-4W

The AD-4W was the airborne early warning version of the Skyraider derived from the AD-4, and the most numerous of its kind: 168 were built. It had no offensive armament and carried a crew of three. Its distinguishing feature was the large ventral radome housing the AN/APS-20 search radar, the same radar family already fitted to the AD-2W in its AN/APS-20A form. The Skyraider's early warning line had begun with the three-seat XAD-1W prototype, and in the US Navy these aircraft replaced the Grumman TBM-3W Avenger in the task of watching the fleet's surroundings from the air. In the Korean War, early warning Skyraiders were part of the range of versions, day and night attack, countermeasures and early warning, that the Navy used in the conflict. In American service the early warning Skyraider was eventually replaced by the Grumman E-1 Tracer.

The AD-4W's most distinctive career was British. In 1951 the Royal Navy received 50 AD-4Ws through the Military Assistance Program under the Mutual Defense Assistance Act, and the Fleet Air Arm designated them Skyraider AEW.1. At first 778 Naval Air Squadron was responsible for training the crews at RNAS Culdrose in Cornwall, until July 1952. On 7 July 1952, 849 Naval Air Squadron was re-established there as the airborne early warning squadron, commanded by Lieutenant Commander J. D. Treacher, and every British AEW.1 served with it. Its job was to give the fleet early warning of potential attacks by ships and low-flying aircraft. The Headquarters Flight trained aircrew before they joined the operational flights of four aircraft that periodically embarked in the fleet carriers.

In November 1952 'A' and 'B' Flights were established; 'A' Flight was the first to go to sea, aboard HMS Eagle in January 1953, while 'B' Flight moved to RNAS Hal Far in Malta. In the following years 'C', 'D' and 'E' Flights were formed, reorganised several times and rotated between the carriers Eagle, Glory, Ark Royal, Bulwark, Albion, Victorious and Centaur. In November 1956 'A' Flight, still in Eagle, took part in the Suez operation, flying continuous barrier patrols around the fleet and the Egyptian coast, during which it located two E-boats that were subsequently destroyed; aircraft embarked in HMS Albion also took part in the crisis. The squadron's last sea deployment with Skyraiders began in Albion in February 1960.

From 1960 the Fairey Gannet AEW.3, fitted with the same AN/APS-20 radar, replaced the British Skyraiders: 849 Squadron gave up the type in December 1960 and the last ones were retired in 1962. The radar outlived the airframe, because in the late 1960s the AN/APS-20 sets removed from the Skyraiders were installed in the Royal Air Force's Avro Shackleton AEW.2s, which provided airborne early warning coverage until they were finally retired in 1991.

There was one last chapter. Fourteen ex-Royal Navy Skyraider AEW.1s were sold to Sweden, where Svensk Flygtjänst AB operated them between 1962 and 1976. All military equipment was removed and they served as target tugs supporting the Swedish Armed Forces, a civilian life that stretched the AD-4W's career to almost three decades after it entered service.