The United States Air Force (USAF) is in the midst of a watershed moment as its first sixth-generation stealth bomber comes online while also rapidly investing in low-cost uncrewed platforms. As the world’s largest military air power is contending with the dual threat axis of asymmetric and near-peer adversaries, it is also facing a recruiting shortfall that leaves many pilot billets vacant. Meanwhile, its intake of new planes is falling short of a replacement rate as decades-old aircraft reach the end of their serviceable life.

The USAF is divesting legacy platforms to make room in the budget and on the flight line for next-gen aircraft, but it is sunsetting airframes at triple the rate that it is procuring new ones. The disparity in the retire-to-buy rate has put the service under an inventory of 5,000 airframes in total for the first time. The cause primarily stems from a trifecta of chronically troubled deliveries with two of the latest planes, prolonged development of advanced drones, and the late start of the Next Generation Air Dominance program.

Operation Epic Fury earlier this year revealed the importance of greater investment in low-cost platforms which directly contradicted the funding increase after Boeing was awarded the contract for the NGAD in early 2025. Even deliveries of the Boeing F-15EX Eagle II have been slow due to supply chain disruptions and a labor dispute at the company’s largest defense manufacturing plants. With many jets already retired, forced readiness and aircraft availability have dropped precipitously, with capability gaps being filled by older jets for years longer than anticipated.

Divest-To-Invest: Replacing Tired Iron On The Flightline

Credit: US Air Force

The baseline explanation behind the US Air Force dropping down to a roughly 4,900-strong fleet is intentionally cutting legacy platforms that are no longer financially viable or survivable in high-end modern conflicts.

“We’re protecting the current force’s capabilities at what we think is an acceptable level of risk,” Secretary of the Air Force Frank Kendall told Air & Space Forces Magazine in 2024.

Freeing up funding from the sustainment of older planes allows it to be redirected into modernization programs.

The USAF currently has the smallest fleet since it was formally established 78 years ago, and the average age of its planes stands at 32 years old. The combination of weary warbirds and malfunctioning replacement aircraft saw mission-capable readiness rates plunge to a low of 62% in 2025. That breaks down to just under 2,000 airframes lacking full combat capabilities at any given time. For comparison, the Air Force average airframe age was 17 years old in 1994 with readiness at 73%, according to Defense News.

Air Force Chief of Staff General David Allvin commented on the numbers to the Air and Space Force Association’s AFA Warfare Symposium in March 2025.

“You wouldn’t know this on the front lines because of the miracles that are going on from our maintainers and those who are sustaining [the planes]… We’re eating into whatever margin we had.”

As maintaining legacy planes, or ‘tired iron,’ eats up a larger percentage of the defense budget, less money remains available to buy new jets. This forces the Air Force to fly its remaining old planes even harder, wearing them out faster and accelerating the cycle. To break away from the financial burden of managing old planes, the Air Force has been executing its aggressive divest-to-invest strategy. Even with the future fleet plans, this historic drop in capacity has caused alarm among military analysts and lawmakers.

The Cold War Fleet Heads To The Boneyard

Credit: US Air Force

The Air Force has been aggressively retiring planes this year, as it did in 2025, and while it will slow down the pace next year, the service is still planning to send many older aircraft to the boneyard. One of the reasons the Air Force divestment rate is higher than its procurement rate is that the defense industrial base can’t accommodate the volume of USAF orders, which is outstripping production. General John Lamontagne told Air and Space Forces Magazine in June that the demand can be challenging to address.

“It’s [about] how quickly can industry respond to our demand signal? And right now, I’d say our demand signal is outstripping their ability to produce quality airplanes on schedule, on time. It takes them a while to facilitize, to be able to either stand up another line or to produce more airplanes over time. Candidly, we probably had some more opportunities

to buy, but industry can’t quite respond that quickly to what we’d like to do.”

In response, the service is extending the service of a small number of the highest performing legacy aircraft. Subsequently, the number of planes expected to be sunset next year will be about half of those planned through the rest of 2026. Below is a side-by-side comparison between last year, this year’s expectations, and current plans for next year:

Particularly noteworthy is the situation of the A-10 Warthog. The venerable old tank buster has proven to be a cost-effective and rugged drone killer in Operation Epic Fury against Iran’s asymmetric tactics. In the budget originally proposed in December 2025, the Air Force wanted to send the entire remaining fleet of 162 examples to the boneyard, as shown in the divestment schedule above. Instead, they have been blocked by Congress, and the type’s retirement will slow down significantly, with dozens expected to continue flying until 2030.

Building The Air Force Of The Future

Credit: US Air Force

The Lockheed Martin F-35 Lightning II fighter program has experienced significant technology hurdles since entering service. This year, the Department of Defense released a damning report that showed fleet readiness drop as low as 25% in 2025 and despite testing throughout the year, the technology refresh 3 block 4 package failed to produce any new capability. As a result, deliveries have been significantly reduced this year.

Meanwhile, Boeing had its share of production issues as well. Its KC-46A Pegasus air-to-air tanker aircraft has also had chronic technology problems like the F-35. Deliveries have been slashed as a result until its three-dimensional camera system and refueling boom can be updated to correct deficiencies. F-15EX deliveries are ramping up now that the strike by machinists is over but the labor dispute also slowed down progress on the F/A-18E/F Super Hornet fighter jet line for the Navy and the upcoming T-7A Red Hawk trainer jet being built in collaboration with Saab.

Keeping American Air Power Combat-Ready

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Two of the best-performing programs right now are the Northrop Grumman B-21 Raider stealth bomber, which is the world’s first sixth-generation aircraft, and the Lockheed C-130J Super Hercules.

Most headlines and attention are devoted to the fighter jets, which have consistently fallen below the 72 annual delivery rate the USAF aims for, but autonomous aircraft are receiving a massive amount of investment as well. The Air Force eventually wants to procure 1,000 examples of the collaborative combat aircraft, also known as the loyal wingman drones. The drones are expected to be ‘attritable’ as a kind of cannon fire to protect the ‘exquisite’ airframes like the Boeing F-47 NGAD. Both the General Atomics FQ-42A Dark Merlin and Android Industries FQ-44A Fury are entering low-rate production now.

F-47: The $300 Million Math Problem

Credit: US Air Force

The F-47 is built to be a hyper-advanced platform, but its cost actively prevents the Air Force from rebuilding its numerical mass. Its first flight is optimistically anticipated by the end of 2028. The program has been fast-tracked since Boeing was officially awarded the contract in March 2025, with the first aircraft claimed to have already begun production. However, due to technological roadblocks in developing its variable-cycle jet engines, it may already be as much as four years behind.

The revolutionary powerplant designed to give it long range, the Next-Generation Adaptive Propulsion engine, will not complete prototype manufacturing until 2031. This means early F-47s will have to fly on older, legacy engines. The Pentagon projects the unit cost of a single F-47 to hit $300 million per airframe. For context, one F-47 costs as much as three F-35A Joint Strike Fighters. Because it is so expensive, the Air Force can only afford to purchase a limited fleet of 185 to 200 F-47s.

Ultimately, the F-47 highlights the Air Force’s central paradox. The service is forced to invest billions into an incredibly expensive, low-volume weapon system to win a high-end technological war, while simultaneously leaving itself vulnerable to a severe shortage of aircraft across the globe.