Tail code Tail codes are the markings usually on the vertical stabilizer of U . S . military aircraft that help to identify the aircraft ' s unit and / or base assignment and occasionally other information that is not unique . This is not the same as the serial number , bureau number , or aircraft registration which provide unique aircraft identification . U . S . Air Force . U . S . Air Force uses multiple codes that relate to the aircraft . Since 1993 , all USAF components , including Air Force Reserve and Air National Guard ( ANG ) , utilize this system . Two large letters identify the home base , or in some organizations , an historic legacy , such as " FF " ( " Fighting First " ) for the 1st Fighter Wing or " WP " ( " Wolf Pack " ) for the 8th Fighter Wing . Air National Guard units usually use the two - letter state abbreviation as a tail code , though there are exceptions , such as the 110th Airlift Wing using " BC " ( " Battle Creek " ) instead of the " MI " used for other Michigan Air National Guard units . Individual aircraft are further identified by three smaller numerals that are the last three digits of the airframe ' s serial number , usually preceded by two smaller digits that indicate the fiscal year that the aircraft was ordered . All aircraft of all types assigned to a unit , or in the case of ANG units , the entire state , use a common code . In some instances , such as Air Force installations in Alaska ( AK ) and Hawaii ( HH ) , all aircraft of all components share a common code . Typically , units of different commands co - located at the same base use different codes . For example , the 509th Bomb Wing at Whiteman AFB , Missouri , uses " WM " while the 442nd Fighter Wing of the Air Force Reserve at the same base uses " KC " ( " Kansas City " ) . Air Mobility Command markings . Air Mobility Command ( AMC ) aircraft do not use two - letter identification codes , but instead have the name of the base written inside the tail flash . AMC aircraft also use a different standard to identify the aircraft serial number . They use a 5 - digit number in which all 5 digits are the same size . In most cases , the first digit represents the last digit of the fiscal year ( FY ) and the remaining digits identify the 4 - digit sequence number . In cases where more than 10 , 000 aircraft were ordered in a single year ( 1964 , for example ) , the complete 5 - digit sequence number - without FY identification - is used . U . S . Navy . U . S . Navy Aircraft tail codes are used to organize an aircraft in Carrier Air Wings , support units not deployed on an aircraft carrier or not deployed overseas , and training commands . In Carrier Air Wing tail codes , the first letter denotes which fleet the Air Wing deploys from ; A for Atlantic Fleet and N for Pacific Fleet . Tail codes in this category are organized as follows : There are slight exceptions to this rule , as Fleet Replacement Squadron s for carrier based aircraft use the CVW style tail codes for the side of the country the unit is based from AD signifying a unit based in the Eastern U . S . and NJ from the Western US . Also , the US Naval Reserve ' s Tactical Support Wing ( formerly Reserve Carrier Air Wing 20 ) uses tail code AF . Training Command aircraft , used for training prospective Naval Aviators and Naval Flight Officers use a single - letter tail code , which denotes the aircraft ' s parent training wing and , as such , home port . Aircraft not assigned to the two above categories fly with any one of a number of unique tail codes that are assigned depending on specific unit and the unit ' s role / home port , etc . U . S . Marine Corps . U . S . Marine Corps tail codes tend to remain the same for the entire history of the squadron no matter where the home base . However , like U . S . Navy aircraft , Marine aircraft have been specially assigned to a carrier group and their tail codes have changed during those assignments .