21st Troop Carrier Squadron, Heavy and 21st Troop Carrier Squadron, Medium Unit 4

Constituted as 21 Transport Squadron on 7 Mar 1942. Activated on 3 Apr 1942. Redesignated as 21 Troop Carrier Squadron on 5 Jul 1942. Inactivated on 31 Jan 1946. Activated on 15 Oct 1946. Redesignated as: 21 Troop Carrier Squadron, Heavy, on 21 May 1948; 21 Troop Carrier Squadron, Medium, on 2 Feb 1951; 21 Troop Carrier Squadron, Heavy, on 1 Dec 1952; 21 Troop Carrier Squadron, Medium, on 18 Sep 1956; 21 Troop Carrier Squadron on 8 Dec 1966; 21 Tactical Airlift Squadron on 1 Aug 1967; 21 Airlift Squadron on 1 Apr 1992-.

Unit 4, a special detachment of the 21st Troop Carrier Squadron, activated in July 1950 on the Island of Kyushu, Japan (thus known as the "Kyushu Gypsies") only 8 days after the start of the Korean War. Under the operational command of the 374th Troop Carrier Wing, Heavy, it began flying spy missions which included night parachute drops behind enemy lines to spy and relay info to orbiting C-47s known as "Operation Aviary". The unit established a Special Air Missions detachment at Taegu AB to fly "white" missions by day, then "black" missions of low-level infiltration flights behind enemy lines at night.