For example, F4U-1A referred to the first minor modification (A) to the first major subtype (1) of Chance-Vought's (U) fourth (4) fighter (F) design.
For the first few years after the system was introduced, the manufacturer's letter and the mission letter were sometimes reversed. If it was the manufacturer's first design for that particular mission, there was no number before the manufacturer letter.
The mission of the aircraft was designated by a one or two letter code. This code would also indicate whether the craft was a glider (L), helicopter (H) or lighter-than-air (Z). Duplicated codes were not in use at the same time.
In cases where an aircraft was its manufacturer's first design for a particular mission, the 1 would not be written. Thus the Consolidated Catalina patrol aircraft was the PBY, not PB1Y, and the McDonnell Phantom was FH, not F1H.
The codes used to denote manufacturers were not unique to a single company as they were reassigned, usually when the company had either ceased operations or had not produced an aircraft for the Navy for a considerable period of time. Additionally, aircraft built under license received a separate design number than the aircraft produced by the designing company. For example, Goodyear produced Vought's F4U as the FG and Grumman's TBF torpedo bomber was produced by General Motors as the TBM. Foreign aircraft generally did not receive a designation under this system unless they were to be built under license in the United States, or were built in Canada for use in the U.S.
Letters were occasionally appended after the design number, in the same place held for minor modifications to the subtype. Adding 'N' to the Grumman F6F-5 designated the radar equipped nightfighter version of that model: F6F-5N. There was no standarization with these codes.
End of the system
In 1962, the Department of Defense unified its aircraft designation systems along the lines of the Air Force's system. Many Navy aircraft then in service were redesignated. For many planes, the mission letters and design numbers were retained, as the AD Skyraider became the A-1 and the F4H Phantom II became the F-4. Some aircraft design numbers were not retained, like the North American Vigilante, which was redesignated from A3J to A-5.
A very similar system, the short system, was adopted by the Imperial Japanese Navy Air Service in the late 1920s that differed only in the use of the 1 for the first assigned type, and having letters assigned to match Japanese aircraft and manufacturers.