Starting in July of 1921 (the beginning of FY 1922) a new system was adopted based on procurement within each Fiscal Year. For example, airplane 22-1 was the first aircraft ordered in FY 1922, 23-1 was the first example ordered in FY 1923, etc. This system is still in use today.
It is important to recognize that the serial number reflects the Fiscal Year in which the order for the aircraft is placed, NOT the year in which it is delivered. Nowadays, the difference between the time the order is placed and the time the aircraft is actually delivered can be as much as several years.
Following the passsage of the Lend-Lease Act in 1941, USAAF serial numbers were allocated to US-built aircraft intended for service with Allied air forces during the Second World War. This was done strictly for administrative purposes, even though these aircraft were never intended for USAAF service. Later, during the Cold War, aircraft supplied to US allies under the Mutual Aid Program or the Mutual Defense Assistance Program were assigned USAF serial numbers for record-keeping purposes, even though they never actually served with the USAF.
Not all the aircraft which served with the US Army Air Force were issued USAAF serial numbers. The best-known examples are those aircraft acquired abroad by the US Army during the Second World War. In most cases, they operated under their foreign designations and serials. For example, the Spitfires acquired in the UK under "Reverse Lend-Lease" were operated under their British designations and their British serial numbers.
Occasionally, USAF aircraft are extensively remanufactured to bring them up to modern standards or to fulfill completely new roles for which they were not originally designed. In many cases, these aircraft are re-serialed with new numbers relevent to their year of re-manufacture. However, this rule is not always followed--re the rather grotesque modifications inflicted on some C-135 aircraft which did not result in new serial numbers.
The US Navy and the US Marine Corps have an entirely different serial numbering scheme, based on numerically progressive numbers allocated by the Bureau of Aeronautics. Occassionally, aircraft are transferred from the Navy to the USAF, and they are given USAF serial numbers constructed by adding additional numbers at the end of the block of the year in which they were originally ordered by the Navy. Aircraft temporarily transferred to the USAF from the Navy usually retain the Navy serial number even though painted in USAF markings, but it sometimes happens that aircraft loaned by the Navy are assigned brand-new USAF serials. Unfortunately, the system is not always consistent.
In recent years, the assignment of USAF serial numbers has not always been in strict numerical order within the FY. Furthermore, an aircraft is sometimes listed in a given FY block when it was actually ordered in a different FY. This is most often done for reasons of special convenience. For example, the serials of the two "Air Force One" VC-137s (62-6000 and 72-7000) might indicate that they were ordered ten years apart, whereas the actual difference was only seven years. The Presidential VC-25s were ordered in FY 1986 under the serials 86-8800 and 86-8900, but these numbers were changed to 82-8000 and 92-9000 by special order to create a series following the two earlier VC-137Cs. When some civilian aircraft have been acquired by the USAF, either by purchase or by seizure, serial numbers have sometimes been assigned out of sequence, with their numbers deliberately chosen to match their former civilian registration numbers. Other times, serial number allocation is done for reasons of secrecy, to conceal the existence of classified aircraft from prying eyes. For example, the serial numbers of the F-117s were initially assigned in strict numerical order, but they were sprinkled among several different fiscal years.
During the 1950s and 1960s, it was common practice to include missiles and unmanned aircraft in USAF serial number batches. Consequently, it is not always possible to determine the total number of aircraft ordered by the USAF simply by looking at serial number ranges.
Following the splitoff of the USAF from the US Army, the Army continued to use the same serial number system for its aircraft, with the serials for Army and Air Force aircraft being intermixed within the same FY sequence. Beginning in FY 1967, the Army began using serials beginning at 15000 for each FY, so Army aircraft could usually be distinguished from USAF aircraft by their high serial numbers. In FY 1971, the Army went over to a new serial series, which started at 20000 and had continued consecutively since then. Within each FY, the US Army numbers are much higher than the USAF numbers are ever likely to get, so there is not much danger of any overlap.
Fiscal year serials with individual numbers less than 100 are filled up with zeroes to bring them up to 3 digits. So 37-52 is written as 37-052. However, for individual serial numbers greater than or equal to 100, there are no zero fills at all. So 48-172 is written as 48-172, not as 48-0172. This is an official regulation which has not changed over the years, no matter how much the actual presentation of the number on the tail or in documents has varied.
The following is a list of serial numbers for US Army and USAF aircraft from 1922 onward. It is incomplete, with numerous gaps. If I know the disposition of a particular aircraft, or if the aircraft has some special historical significance, this information is listed here too. Enjoy yourself brousing through these lists--there are lots of neat historical interludes provided here. These lists are by no means complete or error-free and I would appreciate hearing from anyone who has additions or corrections.
There are a lot of people who want to know about the operational history or ultimate disposition of a particular aircraft referred to in this database, but about which I have little or no information. If you have a specific question about the history of a particular USAAF/USAF aircraft, you might try the
Air Force Historical Research Agency
which is located at Maxwell AFB, Alabama. They have cards on virtually every aircraft ever owned or operated by the USAAC/USAAF/USAF, and they might be able to answer your question fairly quickly. However, you are always welcome to e-mail me in any case and I will see if I can dig up something.
MAIL comments and/or suggestions to:
jbaugher@worldnet.att.com
