Boeing F-15 variants outperform F-35 and F-22 in combat readiness evaluation

The U.S. Air Force operates one of the most formidable air fleets globally, reflecting decades of strategic investment and innovation that have ensured the security of American and allied airspace. As of February 2025, the service manages around 5,000 aircraft, which includes a diverse range beyond just its advanced fighter jets.

This extensive fleet features bombers like the B-52 Stratofortress, refueling aircraft such as the KC-135 Stratotanker, transport planes like the C-17 Globemaster III, and an expanding selection of unmanned aerial vehicles. With a budget surpassing $188 billion for fiscal year 2025, the Air Force maintains a comprehensive arsenal aimed at projecting power on a global scale.

However, beneath this facade of strength lies a concerning situation. A report from the Government Accountability Office in late 2024 highlights issues with aircraft readiness, revealing that the fleet is facing maintenance challenges and operational deficiencies. Notably, the F-15 variants—C, D, and EX—are unexpectedly outperforming the more advanced F-22 and F-35 in terms of mission capability.

The GAO’s analysis provides a detailed look at the operational readiness of the U.S. fighter jets, yielding some surprising findings. The F-15C, a single-seat air superiority fighter developed in the 1970s, recorded a mission-capable rate of 52.9% in fiscal year 2023, a significant improvement from just 33% the year before. Its two-seat counterpart, the F-15D, achieved an even higher rate of 63.7%, up from 55%.

These improvements are the result of a strategic initiative by the Air Force to phase out the oldest and most maintenance-intensive aircraft, resulting in a more streamlined and dependable fleet. The standout performer is the F-15EX Eagle II, Boeing’s updated version of the classic model. With only eight units currently operational, it boasts an impressive mission-capable rate of 83.13%, a remarkable achievement for a platform still in its early stages.

This metric, which indicates the percentage of time an aircraft is capable of executing at least one of its primary missions, underscores the F-15EX’s advantages in terms of reliability and maintenance simplicity. In contrast, the fifth-generation F-22 Raptor experienced a significant drop in readiness, plummeting from 52% to 40.19%. The Government Accountability Office (GAO) attributes this decline to aging systems and a congressional decision to delay the retirement of its Block 20 jets until 2028.

Meanwhile, the F-35A, Lockheed Martin’s stealth aircraft, improved slightly to 51.5% from a previous low, aided by enhanced spare parts availability, yet it still falls short of the program’s goal of 65%. Throughout fiscal 2023, the Air Force allocated $4.9 billion for fighter sustainment—$1.2 billion over budget—yet these advanced stealth aircraft remain grounded more frequently than their older models.

Despite their advanced technology, the F-22 and F-35 are hindered by numerous sustainment issues, as detailed by the GAO. The challenges facing the F-22 are varied: its stealth coatings deteriorate over time, necessitating labor-intensive repairs, and its supply chain is impacted by the disappearance of vendors that previously supplied essential components.

Depot maintenance, intended to refurbish these aircraft, averages 180 days per jet, significantly surpassing the Air Force’s target of 120 days. The F-35’s issues are even more severe, with a lifetime cost now estimated at $1.7 trillion for nearly 2,500 jets, and the program is grappling with a repair backlog of over 10,000 components, some of which may wait up to a year for service.

The GAO identifies a significant lack of technical data as a primary issue, noting that maintainers frequently do not have access to the comprehensive manuals necessary for repairs. This situation is exacerbated by the Pentagon’s heavy dependence on Lockheed Martin for maintenance support. Additionally, organizational maintenance conducted at military bases is further hindered by insufficient training and a lack of necessary support equipment.

In 2023, only 30% of F-35 maintenance tasks were completed within the established timeliness standards, a decrease from 35% in 2022. These challenges have tangible effects: the F-35 fleet managed to fly only 55% of its scheduled hours last year, compelling the Air Force to rely more heavily on older aircraft such as the F-15.

The bomber fleet, crucial to the United States’ long-range strike capabilities, is also facing difficulties. The GAO report highlights three aging platforms that are struggling to maintain operational status. The B-1B Lancer, which can achieve supersonic speeds, increased its mission-capable rate to 46%, still below the halfway mark, but only after retiring its most fatigued units.

The B-2 Spirit, a stealth bomber with a staggering price tag of $2 billion per aircraft, experienced a decline in readiness to 39%, a drop of 1.5 points from 2022, due to the complex nature of its systems requiring specialized maintenance that depots are often unable to provide. Meanwhile, the B-52, a veteran of over 70 years of service from the Cold War era, saw its readiness decrease to 41%, down from 42.5%, despite a $10 billion investment in upgrading its engines and avionics.

In 2023, the Air Force achieved only 67% of its planned flight hours, a deficit attributed by the GAO to shortages in parts and an overextended maintenance workforce. The B-52, for example, depends on engines that were last manufactured in the 1980s, and the initiative known as “Drive to 55,” which aims for a 55% readiness rate, has faltered due to diminishing supplier support.

These bombers are essential, especially since the B-21 Raider, the upcoming stealth bomber, will not be operational until later in the decade, leaving the Air Force to manage with aging aircraft.

Amid these challenges, Pete Hegseth, who was confirmed as Defense Secretary in January 2025, is tasked with reevaluating Pentagon expenditures. With the defense budget limited to $849.5 billion as per the 2023 Fiscal Responsibility Act, Hegseth has already halted the Air Force’s “Re-Optimization for Great Power Competition” initiative, a $30 billion project designed to counter China.

The GAO has reported that sustainment costs for fighter jets surged by 24% above the 2018 projections from 2018 to 2023, leading Hegseth to suggest reducing the procurement of new F-35s from 48 to 42 in FY25 and F-15EXs from 24 to 18. He is instead reallocating funds to enhance readiness, proposing $75.6 billion for operations and maintenance in FY25, an increase of 1.7%, asserting that a smaller, more effective fleet is preferable to a larger, dysfunctional one.

Critics, including members of the Senate Armed Services Committee, express concerns that this situation may lead to a loss of technological advantage, particularly as the flyaway cost of the F-15EX [$89.8 million] approaches that of the F-35A [$85.8 million] when fully equipped.

Hegseth argues that the GAO’s findings, which highlight a gap between expenditure and operational readiness, support his position. Nevertheless, with $37.7 billion allocated for research and development on initiatives such as the B-21 and NGAD fighter, the Air Force’s future relies on effectively balancing innovation with the maintenance of current aircraft.

At the same time, China’s air power is advancing rapidly, necessitating scrutiny. The Pentagon’s 2024 China Military Power Report, which aligns with the GAO’s assessment, estimates that the People’s Liberation Army Air Force operates over 2,400 combat aircraft—an inventory surpassed only by the U.S. and Russia.

The J-20 stealth fighter, approaching 200 units, competes with the F-22 in terms of quantity, while the J-16 multirole jet contributes more than 100 new airframes each year. The J-10C, a lightweight fighter, further strengthens the fleet with additional units annually, and the J-35, inspired by the F-35, is poised to enhance China’s naval aviation capabilities.

The H-20 bomber, which remains classified, is expected to offer stealth and range comparable to the B-2. In 2024, China conducted joint bomber operations with Russia near Alaska, indicating a transition from a focus on regional defense to a broader global strategy. The PLA’s stockpile of 600 nuclear warheads, an increase of 100 since 2023, along with a developing air-launched ballistic missile capability, suggests the evolution of a more sophisticated nuclear triad.

Analysts highlight China’s emphasis on developing indigenous engines, such as the WS-15 for the J-20, alongside a commitment to “actual combat” training. This approach resulted in PLAAF pilots accumulating 20% more flight hours in 2023 compared to the previous year. With production capabilities significantly surpassing those of the U.S. — evidenced by the F-35 program delivering only 98 jets in 2023 — China’s total fleet of 3,150 aircraft presents both a numerical and increasingly qualitative challenge.

As the U.S. engages in discussions regarding budgets and maintenance, Beijing’s continuous military expansion reveals a critical truth: America’s air superiority can no longer be taken for granted.