How do F-35 mission-capable and sortie-per-aircraft metrics compare across services (USAF, USN, USMC) and partner nations?
Executive summary
Mission-capable (MC) and sortie-per-aircraft metrics for the F-35 show a mixed picture: U.S. Air Force F-35As have operated at roughly half of the time mission-capable in recent years, U.S. services and watchdogs point to a much lower “fully mission capable” (FMC) share, and published analyses tie lower availability to parts, maintenance and aging that depress flying hours per aircraft [1] [2] [3]. The Navy and Marine Corps report pockets of better performance against Joint Program Office goals, and Lockheed delivery rates are improving capacity, but public data on partner-nation MC and sortie rates are sparse or inconsistent in government reports [4] [5] [6].
1. U.S. Air Force: roughly half-time MC, flying hours falling
The Government Accountability Office and service-reported figures placed the Air Force F-35A mission-capable rate near 51.9% in fiscal 2023—a decline from prior years and a significant driver of overall fleet readiness concerns [1]. Defense News and the Air Force’s own reporting show that these lower MC rates contribute heavily to a downward trend in fleet-wide readiness and fewer available aircraft to fly daily, which in turn reduces average flying hours per aircraft [7] [8]. Congressional analysts quantify use in flying hours per aircraft and show availability and use fall as jets age, underscoring that reduced MC correlates with lower sortie-generation capacity over time [3] [9].
2. Navy and Marine Corps: pockets of success, variant-specific shortfalls
The F-35C (Navy) and F-35B (Marine) variants have struggled with full mission availability, with the Congressional Budget Office noting that only the newest B and C airframes have generally exceeded a full-mission-availability threshold above 10%—a stark measure because FMC requires the jet be capable of all assigned missions, not just one [3]. Still, operational commanders report progress: Navy wings have told reporters they already surpassed Joint Program Office goals for MC in some squadrons, and the JPO has set a target profile (64% MC, 21% NMC due to supply, 15% NMC due to maintenance) that some Navy units claim to meet [4]. That contrast highlights variation by unit, variant, and localized supply-chain fixes.
3. Fleet-wide FMC vs. MC: two metrics, two stories
Watchdog reporting stresses the gap between the commonly cited MC rate (can execute at least one mission) and the more demanding full mission capable rate (can execute all missions); DOT&E and advocacy groups flag a fleet-wide FMC figure near 30% in recent reporting, a far weaker indicator of combat readiness than headline MC statistics [2]. The GAO and CBO both emphasize that MC can mask important shortfalls—aircraft counted as “available” may lack systems required for full combat employment—so sortie-generation expectations should be tempered by the FMC picture [6] [8].
4. Sortie-per-aircraft: constrained by parts, sustainment, and aging
Analysts and the CBO calculate sortie capacity via flying hours per aircraft, and they find that operating tempo per plane has declined as availability drops and as aircraft age; sustainment bottlenecks and high O&S costs further depress sorties per airframe [3] [9]. The Joint Program Office’s “War on Readiness” and service-level improvisations aimed to raise MC by addressing supply-chain wait times and maintenance practices, with some uplift reported in specific wings—yet GAO and other watchdogs indicate sustainment costs have risen while MC has fluctuated, leaving overall sortie potential below program expectations [4] [10].
5. Partner nations: limited public metrics, heterogeneous outcomes
Government reports list many partner countries as F-35 operators but do not provide comparable, publicized MC or sortie-per-aircraft metrics for those foreign fleets in the same detail as U.S. services; GAO and DOT&E datasets enumerate foreign sales and deployments but stop short of consistent readiness metrics for partners, limiting conclusive comparison [6] [11]. Thus, claims about partner fleets’ sortie rates or MC performance cannot be robustly validated from the cited sources; public evidence instead shows heterogeneity in outcomes driven by variant mix, age, and national sustainment arrangements [6] [11].
6. Competing narratives and implicit incentives
Defense officials and program managers stress improvement plans and cite unit-level successes and increased deliveries—Lockheed reported accelerated deliveries in 2025—which boost fleet size and provide raw capacity for sorties [5] [4]. Critics and watchdogs counter with GAO, DOT&E and CBO findings that emphasize persistent low FMC, rising sustainment costs, and variable MC across variants and services [2] [6] [3]. Both perspectives carry incentives: services want operational narratives that sustain budgets and recruitment, while oversight bodies highlight problems to drive reform and Congress to act.