1956 United States Army aircraft designation system

List of designations and use

• AC-1 De Havilland Canada Caribou - became the CV-2 in the 1962 tri-service designation system.

• AO-1 Grumman OV-1 Mohawk - became the OV-1 in 1962.
• AO-2 Goodyear Inflatoplane
• AO-3 Goodyear Inflatoplane

• AU-1 Not used but reserved for the De Havilland Canada Otter - became U-1 in 1962.

• HC-1A Vertol Model 107 - became the CH-46 in 1962.
• HC-1B Boeing Vertol Model 114 - became the CH-47 in 1962.

• HO-1 Sud-Ouest Djinn
• HO-2 Hughes 269
• HO-3 Brantly B-2
• HO-4 Bell YOH-4 - became the OH-4 in 1962.
• HO-5 Fairchild-Hiller FH-1100 - became the OH-5 in 1962.
• HO-6 Hughes 369M - became the H-6 in 1962.

• HU-1 Bell HU-1 Iroquois - became the UH-1 in 1962.

• 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 XV-4 in 1962.
• VZ-11 Ryan VZ-11 Vertifan - became the XV-5 in 1962.
• VZ-12 Hawker Siddeley P.1127 - not used.