Actual availability of the F-35, time-on-target, and support costs. What changes do ALIS and ODIN bring? Figures, bottlenecks, and avenues for recovery.
In summary
The issue of the F-35’s availability rate remains sensitive because public figures vary depending on the source and the period. Recent data indicate “mission capable” rates of around half the fleet, well below the targets set by the armed forces, while “full mission capable” rates remain significantly lower. The causes are well known: maintenance delays in depots, parts shortages, wear and tear on the F135, and the complexity of the ALIS digital support system, which is currently being replaced by ODIN. Added to this are delays in the TR-3/Block 4 upgrade, which indirectly affect employment. “Time on target” therefore depends on the actual capacity to generate sorties at the requested slot, which combines availability, maintenance rate, and logistics. There are ways to improve the situation (industrialization of engine depots, ODIN cloud, performance contracts, spare parts stocks), but they require constant funding and rigorous technical governance to translate promises into measurable operational availability.
The context of the figures and what they mean
Before making any comparisons, it is important to distinguish between two indicators. Mission capable (MC) measures the proportion of aircraft capable of performing at least one mission. Full mission capable (FMC) indicates the proportion ready to perform all planned missions. Fleet targets typically range between 75% and 90% depending on the version, but recent public data show a significantly lower average MC. For the US Air Force, official figures for 2023 cite an MC of around 52% for the F-35A, while joint summaries mention MCs close to 60% for the F-35B and F-35C, without reaching internal targets. The FMC, which is more demanding, remains much lower and varies greatly with the age of the airframes and the condition of the avionics. At the same time, budget reports show a decline in availability as the fleet ages and lower-than-expected utilization, a sign that operations have had to adapt to the reality of support.
Ambitious goals faced with support constraints
Since 2018, the official trajectory has been aimed at a gradual increase. However, audit reports show stagnation or even a decline, despite increased support spending. The dominant factors are access to parts, scheduling of depot repairs, and the maturity of software chains. In this context, announcing an annualized MC is not enough: what matters to an air component commander is the window of availability “at time T” to maintain a support, interdiction, or defense suppression slot. It is this granularity that determines “time-on-target.”
The role of ALIS and the switch to ODIN
The ALIS system was supposed to automate maintenance, parts management, and part of the mission plan. In practice, it generated erroneous reports, delays, and administrative detours, increasing the workload for mechanics. Several audits pointed to incomplete or inaccurate data, which could ground perfectly healthy aircraft until manual verification. The transition to ODIN aims to migrate the infrastructure to the cloud, lighten the local hardware load, speed up the distribution of patches, and ultimately raise the MC. However, the first step is mainly to transfer the existing system to a more flexible architecture; the major gains will come from software upgrades and more refined integration of flows (maintenance, supply chain, planning).
Measurable impact on availability
In concrete terms, each “false positive” or delay in parts delivery immobilizes an aircraft. When a base operates around 20 aircraft, a deviation of 5 to 10 MC points can disrupt planning: reduced patrols, reprioritized targets, longer rotations. ODIN’s stated ambition is to reduce these frictions by shortening cycle times, improving data quality, and streamlining procurement. Program managers also point to a downward trend in cost per flight hour thanks to these upgrades. One thing remains constant: the effects on availability are only sustainable if software, depots, inventories, and spare parts budgets are aligned simultaneously.
Technical bottlenecks: F135, TR-3, and Block 4
The F135 has experienced module shortages, with queues at depots and historical underfunding of spare parts. In addition, the increased cooling and energy requirements of Block 4 functions place greater demands on the engine, resulting in increased wear and tear and associated workshop hours. TR-3 delays have disrupted delivery schedules and software standardization across the fleet, complicating maintenance and training. The impact is twofold: short-term availability reduced by downtime and projected support costs rising over the program’s lifetime.
What the budget trajectories say
Updated estimates now put the total cost of the program (development, production, and support) at over $2 trillion over its lifetime, due to the combined effect of fleet reconfigurations, reduced flight hours, and modernization re-baselines. However, the latest independent analyses highlight that operating costs per aircraft and per hour have stopped rising and are stabilizing, with more favorable comparisons for the F-35A compared to certain heavy fighters, but still unfavorable compared to older F-16s. Stabilizing costs is not enough: the challenge is to transform these expenditures into tangible availability.
“Time-on-target”: an operational interpretation
“Time-on-target” (TOT) is not a publicly disclosed indicator. However, it can be approximated by the ability to generate sorties exactly within the requested window. Two parameters dominate: the MC/FMC at the moment and the sortie generation rate. The reference documents set “sortie generation rate” (SGR) targets for each variant. As an indication, the CTOL version (F-35A) aims for around three sorties per day at a sustained rate, with average flight times of around 2.5 hours; the STOVL version has higher targets at peak rates, with shorter sorties. These figures are design targets, not a reflection of the actual status of a wing at a given time.
An example with figures to help understand
Let’s take a squadron of 12 F-35As. With an MC of 52%, there are 6 aircraft capable of at least one mission during the day. If the TOT window requires two waves spaced 3 hours apart, the theoretical SGR would allow the pace to be maintained, but the slightest unavailability (engine, sensors, software) could reduce the package by 1 to 2 aircraft. If an FMC (all possible missions) is required, availability drops even further: only airframes with no open faults on any critical subsystems will be available at time T. In practice, staffs compose packages combining FMC and MC aircraft, adapting roles (strike, ISR, SEAD) and adding margins. This reality explains why an average MC of around 50-60% results, on some days, in tighter TOT packages than expected.
Support costs and their effect on availability
The latest assessments indicate that operating and support costs have stabilized after a period of decline, but at a high level. Several factors explain this: a planned reduction in annual flight hours, which dilutes fixed costs less quickly; the expansion of depots and the gradual ramp-up of repair capabilities; and the replenishment of parts inventories. The armed forces emphasize the value of “performance-based” support contracts, which align industrial incentives with the objective of availability rather than the volume of activity. However, experience shows that these contracts only have a lasting effect if they are backed by concrete investments in parts and depots, and robust data governance on the ODIN side.
Where are the margins for improvement?
Three levers dominate. First, the complete industrialization of engine and avionics depots to reduce downtime. Second, the elimination of “false positives” via ODIN and the improvement of data quality; each unfounded alert consumes man-hours and disrupts schedules. Finally, TR-3/Block 4 standardization: a fleet aligned to the same software standard facilitates the exchange of aircraft between units, training, and spare parts management.
Operational feedback and the “peace/combat” differential
Several officials reported that, when deployed in operations, the F-35s achieved MCs higher than the annual averages, thanks to prioritized support and dedicated stocks. This does not invalidate the overall averages: it shows that concentrated logistics, additional personnel, and abundant parts push the curve upward. In other words, “theater” availability is a resource choice. The question is whether, for a fleet of nearly a thousand aircraft, the same levels are sustainable over time, and at what cost.
What could change the game between now and 2030
If ODIN achieves its objectives (reliable data, agile updates, supply integration), and if the F135 chain gains momentum in the depot, MC/FMC rates may rise back towards internal targets. The consolidation of TR-3 and the ongoing commissioning of Block 4 capabilities will also prevent fragmentation of standards. Conversely, any slippage in the software upgrade schedule or renewed pressure on critical parts will keep availability below targets. “Time on target” will remain the ultimate indicator: the ability to deliver the required number of aircraft, with the right sensors and weapon configuration, at the requested time slot.
A provisional verdict on “true” availability
Based on the most recent public data, the actual availability of the F-35 can be summarized as follows: an aggregate MC close to half the fleet, an FMC that is much lower and highly variable depending on the standard, and a “time-on-target” that is closely dependent on local planning, inventory, and software maturity. The budgetary trend suggests a stabilization of operating costs, but not yet a shift towards availability that is consistently in line with objectives. The difference will be made in the implementation of support reforms rather than in the announcement of plans.
The F-35 is now paying the price for unprecedented technical ambition: sensors, stealth, and software were supposed to combine to deliver lasting superiority; for years, they fragmented the support chain. The program is entering a decisive phase in which support, data, and depot engineering will be as important as aerodynamics. If ODIN delivers on its promises and the F135 supply chain absorbs the load, the fleet will be able to transform billions spent into hours actually available in the air. If not, there is a risk that availability rates will remain the most scrutinized—and most disappointing—statistic for an aircraft that is nevertheless formidable once it is lined up “at the hour H.”
War Wings Daily is an independant magazine.