United States military aircraft serials In the United States , all military aircraft display a serial number to identify individual aircraft . These numbers are located on the aircraft tail , so they are sometimes referred to unofficially as " tail numbers " . On the Northrop Grumman B - 2 Spirit bomber , lacking a tail , the number appears on the nose gear door . Individual agencies have each evolved their own system of serial number identification . History . United States Army Signal Corps . In 1908 , the United States government purchased its first heavier than air aircraft . The aircraft , a Wright Model A , was used by the aviation section of the United States Army Signal Corps , and was issued with serial number 1 . Subsequent aircraft were numbered in sequence . United States Army Air Service . In 1918 , the aviation section of the Army Air Service became the United States Army Air Service ( USAAS ) , but the sequence of numbers started in 1908 continued without change . In 1920 , the USAAS became independent from the Signal Corps , and by 1921 the sequence had reached 68000 . On 1 July 1921 , a new serial system was introduced that was based on the United States Fiscal Year , which continues to the present day . For example , the first aircraft to be procured with fiscal year 1960 funds was a Boeing B - 52H serialed " 60 - 001 " . United States Army Air Corps . In 1926 , when the USAAS became the United States Army Air Corps ( USAAC ) , the sequence continued unchanged . United States Army Air Forces . In 1941 , when the USAAC became the United States Army Air Forces ( USAAF ) , the sequence continued unchanged , and the displayed number , normally shown on the fixed vertical stabilizer ' s sides , usually omitted the first digit of the year of the contract issuance . United States Air Force . In 1947 , when the USAAF became the United States Air Force ( USAF ) , the sequence continued unchanged . Although USAF was independent from the Army , Army aircraft continued to be allocated in the same numeric sequence until 1967 . United States Army . In 1967 , the United States Army continued to use the fiscal year serials , but the numeric element was started at 15000 for each year . In 1971 , the sequence was started at 20000 , and was not restarted with each fiscal year . United States Navy and Marine Corps . In 1911 , the United States Navy ( USN ) purchased its first aircraft , a Curtiss Triad pusher floatplane . The Navy allocated a prefix for each manufacturer , and the first aircraft was serialed " A - 1 " , with A allocated to Curtiss . Different letters were also allocated to the same manufacturer , but for different types of aircraft , for example Curtiss amphibians were allocated E . In early 1914 , the system was changed to a two - letter type / sub - type system , with each having a sequence starting from 1 . A was allocated for heavier - than - air types for example AB was a flying boat and AX was an amphibian . All surviving aircraft from the original system were reserialled . In 1917 , the individual number sequences were stopped , and a combined sequential numerical system was started at number 51 . Prefix letters were retained for a short time , but in 1917 they were replaced with single letter A for aeroplane . The numbers were official " designating numbers " , but became known as Bureau Numbers ( BuNos ) due their assignment by the Navy Bureau of Aeronautics . In 1930 , the service ceased using the A prefix ; the last such serial was A - 9204 . In 1935 , when the sequence reached 9999 , the sequence was restarted at 0001 . At the start of the 1940s , so many aircraft were purchased that surviving aircraft from the first sequence could be confused with second - series aircraft , and the sequence was stopped at 7303 . In 1940 , the third sequence was started at 00001 ( with five digits ) . When the third sequence reached 99999 , it continued with six digits which continues to date . United States Coast Guard . In 1926 , the United States Coast Guard purchased its own aircraft , and they were assigned one or two digit serial numbers . In 1934 , the system was changed to a three - digit number with the first digit indicating an aircraft type . In 1936 , this was changed again , and all aircraft ( including those withdrawn from use ) were allocated serials starting with V101 . In 1945 , the V prefix was removed and replaced with digit 1 to make four - digit serial numbers , which continues to the present . Since 1969 , executive aircraft operated for the Secretary of the Treasury were assigned their own sequence beginning with " 1 " . Presentation ( Army / Air Force ) . The early Army aircraft had large black serials marked on the fin or rudder , and in 1917 it was usual to prefix the serial with SC for signal corps , or later AS for aerial service . Later , the prefixes were not always marked , and were eventually dropped . From 1942 , the serial number was applied to the fin ( or boom if a helicopter ) , and the first digit of the fiscal year would be removed . The serial would not be allowed to be less than four digits ( for example B - 45 serial number 47 - 007 was marked " 7007 " ) , but there was no upper limit ( for example YP - 59A 42 - 108783 was marked as " 2108783 " ) . When the original fiscal year of a serial became ten years earlier than the current fiscal year , the tail number was often prefixed with a zero , for example 0 - 16717 instead of 16717 for UH - 1H fiscal serial 66 - 16717 . This was for disambiguation purposes , to avoid confusion with tail numbers for later fiscal years . The practice was generally abandoned in the 1980s . The notion that it was O for Obsolete is a widespread myth . In 1956 , the fin serials were changed from a minimum of four digits to five digits and in 1957 all serials were limited to five digits ( for example KC - 135R 58 - 0001 is marked as " 80001 " ) the system is still in use . In 1969 , camouflaged tactical aircraft were marked with modified presentation with the fiscal year followed by the last three digits of the serial number . Also , the letters AF were often added as a prefix or nearby . Whatever the serial presentation on the fin , the full fiscal serial is always presented in a technical data block , which is normally on the port ( left ) side near the cockpit . Often a portion of the aircraft serial number is also painted on the aircraft nose ( as is done with helicopters ) or on the nose landing gear door ( as is done on fighters and bombers ) to help ground and air crew personnel speedily identify a certain aircraft as it approaches while taxiing into or out of parking spots or elsewhere around an airfield . Presentation ( Navy ) . Each Navy aircraft normally has its serial plus the type designation marked in small letters on the rear fuselage . Sometimes the last four digits of the serial are painted on the fuselage or fin . Sometimes the last three digits are used as the side codes , but on operational aircraft this is normally a squadron assigned code instead of a shortened serial number .