Air Force and Navy Aviation: Actions Needed to Address Persistent Sustainment Risks
Fast Facts
Despite spending billions of dollars annually, the Air Force and Navy have struggled for years to maintain their aircraft due to the age of their fleets, a lack of parts, maintenance delays, and other problems. By the Air Force and Navy's own measures, aircraft readiness has worsened since fiscal year 2015.
Of particular concern is that neither service has completed required "sustainment reviews"—a critical tool to assess performance and help increase readiness throughout an aircraft's life cycle.
We recommend prioritizing and completing these reviews, then reporting to Congress on how identified problems will be fixed.
The Air Force and Navy aircraft in our review—including the F-22 Raptor shown below—totaled 1,355 aircraft that cost about $13.6 billion a year to maintain.
Highlights
What GAO Found
Mission capable rates—a metric used to assess the health and readiness of an aircraft fleet—and other related maintenance metrics trends have worsened since fiscal year 2015 for eight selected aircraft (see figure).
Average Mission Capable Rates, by Percentage, for Selected Air Force and Navy Aircraft, Fiscal Years 2015 and 2021
While the Air Force and Navy have initiatives to address unit-level maintenance challenges, neither service has mitigated persistent fixed-wing aircraft sustainment risks. A statute enacted in 2016 requires the services to conduct sustainment reviews for major weapon systems to assess their product support strategy and performance, among other things. GAO found, however, that the Air Force and Navy have not completed these sustainment reviews for all aircraft (see figure). Both the Air Force and Navy have plans to complete the required sustainment reviews by the end of fiscal years 2025 and 2035, respectively.
Estimated Timeline for Air Force and Navy to Complete Required Sustainment Reviews, as of October 2021
Without the Air Force and Navy prioritizing the completion of required sustainment reviews and updating their schedules to complete the reviews in a timelier manner, the services are missing opportunities to identify maintenance and other risks to aircraft availability. Further, neither the Air Force nor the Navy have completed mitigation plans to remedy maintenance challenges, risks, or related impacts identified in any sustainment reviews. As a result, the Air Force and Navy cannot fully address unit-level aviation maintenance challenges affecting aircraft availability required for training and operations. If Congress required the Air Force and Navy to submit mitigation plans to Congress related to maintenance challenges and risks to aircraft availability found in sustainment reviews, it would enhance the services' accountability for taking the necessary and appropriate actions to address persistent challenges to aircraft availability.
Why GAO Did This Study
The Air Force and Navy spend billions of dollars annually to maintain their aircraft. The ability of the Air Force and Navy to complete aircraft maintenance directly affects military readiness, as maintenance delays reduce the time during which aircraft are available for operations and training.
House Report 116-442 included a provision for GAO to examine unit-level aviation maintenance. Among other things, this report assesses (1) trends in mission capability rates and related maintenance metrics for selected aircraft since fiscal year 2015 (2) the extent to which the Air Force and Navy have mitigated sustainment risks.
GAO selected a non-generalizable sample of eight out of 31 Air Force and Navy fixed-wing aircraft and analyzed maintenance and staffing metrics from fiscal years 2015 through 2021; reviewed sustainment reviews and related DOD guidance; and interviewed DOD, military service, and unit officials.
Recommendations
Congress should consider requiring the Air Force and Navy to provide Congress plans to address risks to aircraft availability found in sustainment reviews. GAO is making four recommendations to the Air Force and Navy to prioritize and complete required sustainment reviews in a timelier manner and develop plans to remedy risks to aircraft availability. DOD generally concurred with the recommendations. The Navy did not agree to complete sustainment reviews in a timelier manner, citing resource limitations. GAO believes the Navy should complete these reviews with a greater sense of urgency.
Matter for Congressional Consideration
| Matter | Status | Comments |
|---|---|---|
| Congress should consider amending section 4323 of Title 10, U.S. Code to require the Air Force and Navy to submit to Congress mitigation plans related to identified maintenance challenges and risks to aircraft availability found in sustainment reviews based on a specific sustainment threshold. Such thresholds could include aircraft falling below their mission capable rate goal for consecutive years; an aircraft's mission capable rate declining by a specified percentage; or some other sustainment metric or metrics. (Matter for Congressional Consideration 1) | As of June 2025, we are continuing to monitor Congressional action that may address this suggestion. |
Recommendations for Executive Action
| Agency Affected | Recommendation | Status |
|---|---|---|
| Department of the Air Force | The Secretary of the Air Force should prioritize the completion of required sustainment reviews and update its planned schedule to complete the reviews in a timelier manner. (Recommendation 1) |
The Department of the Air Force concurred with this recommendation. As of June 2025, the Air Force plans to complete the required Sustainment Reviews by the end of fiscal year 2025. We will continue to monitor the Air Force's progress in completing sustainment reviews.
|
| Department of the Navy | The Secretary of the Navy should prioritize the completion of required sustainment reviews and update its planned schedule to complete the reviews in a timelier manner. (Recommendation 2) |
The Department of the Navy partially concurred with this recommendation and is prioritizing and executing sustainment reviews as delineated in 10 U.S.C. Section 4323 and promulgated by the Office of the Under Secretary of Defense (Acquisition & Sustinament) Memorandum, "Implementation of Sustainment Reviews", dated 2 June 2021, and Assistant Secretary of the Navy (Research, Development and Acquisition) Memorandum, "Gate 7 Sustainment Reviews", dated 27 Sept 2021. The Department of the Navy is conducting sustainment reviews for the 39 covered systems that have achieved IOC plus 5 years. As of June 2025, the Navy plans to complete the required Sustainment Reviews by the end of fiscal year 2026. We will continue to monitor the Navy's progress in completing sustainment reviews.
|
| Department of the Air Force | The Secretary of the Air Force should develop mitigation plans, with specific milestones, to remedy maintenance challenges, risks, or related impacts to aircraft availability identified in completed sustainment reviews. (Recommendation 3) |
The Department of the Air Force concurred with this recommendation and said it would take steps to implement it. The Department of the Air Force agrees the mitigation plans, with specific milestones, should be developed to remedy maintenance challenges, risks, or related impacts to aircraft availability identified in the completed sustainment reviews. Presently, completed sustainment reviews have not identified such maintenance challenges, risks, or related impacts to aircraft availability. The Air Force will continue to monitor future sustainment reviews to identify maintenance challenges requiring mitigation. As of June 2025, the Air Force estimated implementation to occur by the end of fiscal year 2025. When we confirm what actions the Department of the Air Force has taken in response to this recommendation, we will provide updated information.
|
| Department of the Navy | The Secretary of the Navy should develop mitigation plans, with specific milestones, to remedy maintenance challenges, risks, or related impacts to aircraft availability identified in completed sustainment reviews. (Recommendation 4) |
The Department of the Navy concurred with this recommendation and said it would take steps to implement it. As of June 2025, the Department of the Navy reported it has implemented several sustainment initiatives and management controls, including the Naval Sustainment System - Aviation (NSS-A) and Sustainment Program Baseline (SPB), to ensure development and implementation of mitigation plans to remedy maintenance challenges, risks, or related impacts to aircraft availability. When we confirm these actions, we will close the recommendation.
|