1956 United States Army aircraft designation system

The United States Army designation system was introduced by the United States Army in 1956 to replace the designation system used by the United States Army Air Corps which had become the United States Air Force in 1948. it was used until the unified tri-service designation system for all services came into effect.

List of designations and use

 * AC - Airplane, Cargo
 * AC-1 De Havilland Canada Caribou - became the CV-2 in the 1962 tri-service designation system.
 * AO - Airplane, Observation
 * AO-1 Grumman Mohawk - became the OV-1 in 1962.
 * AO-2 Goodyear Inflatoplane
 * AO-3 Goodyear Inflatoplane
 * AU - Airplane, Utility
 * AU-1 Not used but reserved for the De Havilland Canada Otter - became U-1 in 1962.
 * HC - Helicopter, Cargo
 * HC-1A Vertol Model 107 - became the H-46 in 1962.
 * HC-1B Boeing Vertol Model 114 - became the H-47 in 1962.
 * HO - Helicopter, Observation
 * HO-1 Sud-Ouest Djinn
 * HO-2 Hughes 269
 * HO-3 Brantly B-2
 * HO-4 Bell 206 - became the H-4 in 1962.
 * HO-5 Fairchild-Hiller FH-1100 - became the H-5 in 1962.
 * HO-6 Hughes 369M - became the H-6 in 1962.
 * HU - Helicopter, Utility
 * HU-1 Bell HU-1 Iroquois - became the H-1 in 1962.
 * VZ - VTOL research
 * VZ-1 Hiller VZ-1
 * VZ-2 Vertol VZ-2
 * VZ-3 Ryan VZ-3 Vertiplane
 * VZ-4 Doak VZ-4
 * VZ-5 Fairchild VZ-5
 * VZ-6 Chrysler VZ-6
 * VZ-7 Curtiss-Wright VZ-7
 * VZ-8 Piasecki VZ-8
 * VZ-9 Avro Canada VZ-9
 * VZ-10 Lockheed VZ-10 Hummingbird - became the V-4 in 1962.
 * VZ-11 Ryan VZ-11 Vertifan - became the V-5 in 1962.
 * VZ-12 Hawker Siddeley P.1127 - not used.