By Lieutenant Colonel Ronald J. Brown
U.S. Marine Corps Reserve, Retired
During the Korean conflict, the Navy Bureau of Aeronautics used designation systems that conveyed a lot of information about its squadrons and aircraft in a concise manner.
The Bureau recognized three aircraft squadron types: lighter than air (Z); heavier than air (V); and helicopter (H). In addition, Marine aircraft squadrons were identified by the insertion of the letter “M” between the aircraft type and the squadron function. In general, a three letter prefix followed by up to three numbers was used to identify individual Marine aircraft squadrons. The first letter (a “V” or “H”) identified the primary aircraft type used by the squadron, the second letter (“M”) identified it as a Marine aviation unit, and the third (“O” indicating observation and “R” for transportation) identified the squadron’s primary mission; the numbers in the suffix sometimes identified the squadron’s unit affiliation and always noted its precedence order.
Thus, VMO-6 was the sixth heavier-than-air Marine observation squadron formed. The single digit indicated that the squadron was not specifically affiliated with a particular aircraft wing (observation squadrons were attached to ground units). On the other hand, HMR-161 was the first Marine helicopter transport squadron assigned to the 1st Marine Aircraft Wing (the first “1” indicating initial assignment to the wing, numbers above “6” were used for non-fixed wing aircraft, and the last “1” signifying it was the first squadron formed).
Individual aircraft designations used a similar identification system. The Bureau of Aeronautics gave each naval aircraft a mixed letter and number designation. Except for experimental or prototype helicopters, the first letter was an “H” indicating rotary-wing status; the second letter indicated its primary purpose (“O” for observation, “R” for transport, or “T” for trainer); a number (except in the case of the first model) indicated the manufacturer’s sequence for producing that specific aircraft type; the next letter identified the manufacturer (“L” for Bell, “P” for Piasecki, or “S” for Sikorsky); and the number following a dash indicated a sequential modification of that aircraft model.
Thus, the HO3S-1 was Sikorsky Aircraft’s third model observation helicopter with one modification; the HRP was Piasecki’s first transport helicopter; the HTL-4 was the fourth modification to Bell Aircraft’s original trainer helicopter; the HO5S was Sikorsky’s fifth observation model; and the HRS-1 was Sikorsky’s first transport helicopter.
The Bureau’s system was a good one that remained in use for four decades, but there were a few problems. First, aircraft were often used for roles other than those assigned. For example, the HO3S-1 was actually a utility aircraft that during field service performed many tasks other than observation, a task that actually became a seldom-used secondary mission in Korea. Second, the proliferation of missions and manufacturers as time passed led to confusing duplication of letters (“T” was variously used to indicated torpedo, trainer, and transport aircraft). Third, lack of inter-Service consistency produced confusion (the Navy HO3S-1 was an H-5F to the Air Force and Army). The naval aircraft designation system was replaced by a joint aircraft designation system in 1962, but the Bureau’s squadron designation system remains in effect.