1924 United States Army Air Service aircraft designation system

In 1924 problems with the previous designation system led to a general revamping of the designation system used by the United States Army Air Service. This system was to remain in effect with the U.S. Army Air Corps, the U.S. Army Air Forces and the independent U.S. Air Force, as well as those aircraft remaining in the U.S. Army after 1947; and with some minor changes, became the basis of the 1962 when a unified tri-service designation system for all services came into effect.

The designation given to a particular aircraft can be broken down to provide information about that specific aircraft. A hypothetical example shows a typical designation, and what each section is. Tables below indicate possible codes used for each section, what their meanings were, and the time period in which they were used – not all codes were in use at the same time, and some codes, such as P for pursuit were changed to F for fighter for a given aircraft while they were in service, so that the Lockheed P-80 was redesignated as the Lockheed F-80. The portion of the designation after the subtype may be omitted in normal use. The hyphen before the block number may be replaced with the word "block", and in some cases the block number may be omitted. This information, along with the name of the service (USAAC, USAAF, USAF), the base (if permanently assigned) and the serial number was painted on the forward fuselage side under the cockpit.

(generally applied only to specific aircraft)

Used when an aircraft has been modified for a different role from originally designed.

In theory each new design in a specific Mission category is numbered in sequence starting at 1, so that succeeding designs are numbered 2,3,4 etc. however numbers were occasionally skipped.

Minor modifications to a basic design are usually given a sequentially assigned letter denoting the particular subtype, starting with A and continuing with B, C, D, etc. In general, no additional meaning can be deduced from the sub-type letter.

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