The Air Force is running out of airplanes ....
Aircraft retirements, due to age or to budget cuts, have far outstripped new aircraft procurement since the early 1990s.
Let's take a look at the particulars:
F-15A/B/C/D - The Eagle is the air superiority fighter for the USAF. A late '60s design, first production examples reached the front line in 1975. Almost all A and B models have been retired. Most C and D models have been retired. The last air superiority Eagles were built in the mid '80s. After the next round of retirements, coming this next year, less than 200 of these will be operational in USAF and ANG service. This aircraft's direct replacement is the F-22 Raptor.
F-15E - Strike fighter version of the Eagle, was built in the late '80s and early '90s. These aircraft are not being retired yet, but they are not numerous. The operational force hovers around 200-225 aircraft. There is no direct replacement for the Strike Eagle on the boards, though the F-35 is supposed to take over some of its missions.
F-16A/B/C/D - the Fighting Falcon is a mid-70s design. All A and B models have been long since retired. Most C and D models have been retired. Appx. 300 more will be retired in the next year or so. The last USAF Falcons were produced in 1994. Due to its numbers, the Falcon has been the backbone of USAF/AFRES/ and ANG fighter strength for almost 3 decades. The F-35 is to replace the F-16.
A-10 - The Thunderbolt II has risen in importance since the first Gulf War. It was thought to be on its way to the junkyard in the late '80s, but the need for a dedicated close air support platform resurrected it. Multiple upgrades have been performed to extend service live and lethality - the Hog is now expected to serve well into the 2020s. About half of the original production run has been lost or retired, but the remainder is a highly thought of, highly used asset. There is no direct replacement on the board, though some tout the F-35 as its followon.
C-130 - the Venerable Hercules has been around since the early 1950s, and still provides the military with the majority of its theater level transport capabilities. The latest model, the J, continues in slow production, in spite of Pentagon efforts to kill it off. Hundreds of Hercs have been retired, hundreds more will need retirement in the coming decade. There is no replacement on the boards.
C-5 - the largest transport plane in the USAF, the Galaxy comes in two basic models - A and B. the A models were built in the late '60s and early '70s. They are maintenance nightmares, and their in service capability is miserable. The B models were built in the mid-80s, and provide an important long haul capability for large cargo. Numerous attempts to upgrade the C-5s have been proposed over the years, and all of them have been stalled by budget cuts. As a result, the USAF is seeking congressional permission to retire all the A models. There is no replacement for the Galaxy on the boards.
C-17 - The Globemaster III is the current mid-level transport for the USAF. It has filled a critical need for moving cargo, and is still in low rate production, in spite of Pentagon attempts to kill it off. The USAF will end up with a fleet of around 200 of these critical aircraft, far less than needed if the C-5 and C-130 retirements planned come through. There is no replacement for the C-17 on the boards.
KC-135 - the primary (and only) aerial refueling aircraft in the USAF/AFRES/ANG. Hundreds of this workhorse were built by Boeing, with the last ones coming off the production lines in 1964. Hundreds of A and E models have been retired due to age. Hundreds more A models have been rebuilt as R models, and will continue to serve for decades to come. I have seen estimates that tsome of these aircraft will reach 80 years old by the time they are finally retired. Strange as it may seem, aerial tankers are the most important aircraft in the USAF - without them, the Air Force could not function. Replacement has been a hot project for years now, but is not decided. Competition between Boeing and Airbus to produce its replacement has been marred by corruption, political fighting, changing specifications, and international gamesmanship between the companies. The contract for development still has not been awarded.
B-52 - The Old Fort has been around for over 50 years. The newest one off the production line was purchased with FY 1961 money! The only model still in service is the H, and it is seen as a critical component of worldwide force projection. Less than a hundred of them still serve. Upgrades are constant. Projections see the last of them being retired in 2040!
B-1 - The USAF has several times tried to get rid of the BONE. 100 were originally produced, about 60 remain in service today. Numerous upgrades have kept the airplane current - it is a great bomb truck. Will it continue, who knows - it seems there is a new effort to get rid of them about every 5 years or so.
B-2 - This wonderplane is a '80s design. Less than 20 of them are operational at any given time. They are a powerful force, but their lack of numbers would make them ineffective in a prolonged major war.
There are other, more minor aircraft in the mix, but those are the main players.
In addition, in the late '80s and '90s, several aircraft types were retired out of the inventory, with little or no replacement: C-141, KC-135A/E, F-4C/D/E/G, RF-4, A-7, F-111A/D/E/F, EF-111, B-52G, SR-71.
It's a sad state of affairs ... The USAF is running out of aircraft, and the few replacements that have been identified are years away from being available.