At a Glance
In this report, the Congressional Budget Office analyzes patterns in the availability and use of aircraft by the U.S. Army from 2000 to 2023. CBO looks at availability—a measure of the percentage of time aircraft can be flown for training or missions—and flying hours, both in total and per aircraft.
Here are CBO’s findings about the fleet’s size, availability, and use:
- Size. As of 2023, the Army had about 3,900 manned aircraft, most of which were helicopters. The service had an additional 700 large unmanned aerial systems (commonly called drones). Since 2000, the number of manned Army aircraft has generally declined.
- Availability. Unlike the Air Force and the Department of the Navy, the Army experienced an upward trend in the availability of its aircraft from 2000 to 2023. In 2023, the Army’s average availability rate for manned aircraft was 68 percent—that is, those aircraft were in the possession of operational squadrons and capable of being flown for missions for 68 percent of total possible hours. Since 2005, availability of H-60 Black Hawk helicopters (the Army’s largest fleet) has generally been increasing.
- Use. The Army used its helicopters more during the conflicts in Iraq and Afghanistan than at other times over the 2000–2023 period. Total flying hours for manned aircraft peaked in 2008 (at 1.22 million), and average flying hours per aircraft peaked in 2011 (at 302). In 2023, manned aircraft flew for 0.77 million hours, and the average aircraft flew for 198 hours.
- Recent changes. Aircraft availability rates Army-wide increased during the initial months of the coronavirus pandemic, whereas flying hours markedly declined. Both availability and use returned to near-normal levels by early in fiscal year 2021.
Notes
All years referred to in this report are federal fiscal years, which run from October 1 to September 30 and are designated by the calendar year in which they end.
All data in this report come from the GCSS-Army Enterprise Aviation data system.
On the cover: The drawing depicts, from top to bottom, an H-47 Chinook, an H-60 Black Hawk, and an AH-64 Apache.
The Congressional Budget Office has previously published several reports on related subjects, which are listed below (starting with the most recent) for ease of reference:
Availability and Use of the F/A-18E/F Super Hornet Fighter Aircraft (February 2023), www.cbo.gov/publication/58687.
Availability and Use of Aircraft in the Air Force and Navy (January 2022), www.cbo.gov/publication/57433.
The Cost of Replacing Today’s Army Aviation Fleet (May 2019), www.cbo.gov/publication/55180.
The Cost of Replacing Today’s Air Force Fleet (December 2018), www.cbo.gov/publication/54657.
This Congressional Budget Office report analyzes the availability and use of manned and unmanned aircraft operated by the U.S. Army from 2000 to 2023. CBO previously analyzed the availability and use of aircraft in the U.S. Air Force and the Department of the Navy (including the U.S. Marine Corps).
CBO used data from the GCSS-Army Enterprise Aviation data system to evaluate six categories of Army aircraft—namely, three fleets of large helicopters, or rotary-wing aircraft (the Black Hawks, Apaches, and Chinooks); other rotary-wing aircraft, which now consist solely of Lakotas; manned fixed-wing aircraft; and large unmanned aerial systems, or UASs, which are more commonly known as drones. (The category of other rotary-wing aircraft formerly included now-retired Iroquois utility helicopters and Kiowa multirole reconnaissance helicopters.)
The data CBO used for this analysis have three limitations. First, the Army’s data system does not tabulate data about smaller tactical UASs (of which the Army has many), so those aircraft are not analyzed here. Second, data about the large UASs do not appear in the system until January 2021 even though the Army operated those aircraft before then. Third, the helicopters operated by the Army Special Operations Command have not appeared in the data system in recent years.
Types of Aircraft in the Army’s Fleets
In 2023, the Army had about 3,900 manned aircraft, mostly helicopters: 2,100 H-60 Black Hawk medium-transport helicopters, 700 AH-64 Apache attack and reconnaissance helicopters, 500 UH-72 Lakota light-utility transport helicopters, and 400 H-47 Chinook heavy-transport helicopters. The rest were manned fixed-wing aircraft, mostly C-12 Huron passenger transport airlifters. The Army also had about 700 large UASs: 500 RQ-7B Shadows and 200 MQ-1C Gray Eagles.
Trends in the Size of the Army’s Fleets
From 2000 to 2023, the number of Army aircraft fluctuated, but generally decreased. The types of aircraft that the Army operated also decreased.
Trends in the Age of the Army’s Fleets
Whereas the average Air Force aircraft was 28.3 years old as of October 1, 2017, the average Army aircraft has been considerably newer. The comparison between the two services’ aircraft is problematic, however. The Army changes a helicopter’s tail number when the aircraft is upgraded (for example, making an AH-64D Apache into an AH-64E), thereby resetting its age to zero. By contrast, upgraded and modified Air Force aircraft keep their tail numbers, so their ages are not reset.
Those differing approaches reflect a fundamental difference in the stresses borne by helicopters and fixed-wing aircraft. The stresses experienced by fixed-wing aircraft during flight result in wear and tear on the wings and fuselage over many years. Those components are difficult to replace, so extending the service life of fixed-wing aircraft to mitigate accumulated damage can necessitate extensive and costly repairs. The stresses experienced by helicopters during flight are borne largely by the rotor systems (such as blades and hub components), which are designed to be replaced at regular intervals; the fuselage structure of a helicopter is not typically a life-limiting component. Thus, remanufactured helicopters are often considered to be new, but the service life of modified fixed-wing aircraft might still be affected by wear and tear accumulated during prior service.
Changes in the Average Age of Some Fleets
The fleets of Apache and, to a lesser extent, Chinook helicopters maintained fairly static average ages over the 2000–2023 period because older variants of the aircraft were replaced by newer variants over time. (The average AH-64 Apache was 9 years old in 2000; in 2023, the average AH-64 Apache was 8 years old. Likewise, the average H-47 Chinook was 11 years old in 2000; in 2023, the average H-47 Chinook was 12 years old.) The new variants had different tail numbers and therefore were recorded as having age zero upon entry into service.
The pattern for the Army’s largest fleet, H-60 Black Hawks, differs somewhat. Although UH-60Ms have replaced UH-60As, the average age of the H-60 fleet increased from 12 years in 2000 to 18 years in 2023.
Aircraft Availability
To determine a fleet’s availability rate, CBO starts with the number of hours that aircraft are mission capable (either fully or partially capable, meaning the aircraft can perform some but not all of its missions) and in the possession of operational squadrons. Then, CBO divides that number by total possible hours, including those for aircraft receiving maintenance in a depot.
Aircraft Use
CBO measured aircraft use for the fleet as a whole and for each aircraft. Because of missing observations (for October 1999 and September–December 2018) in the data CBO received, the agency extrapolated to estimate flying hours for fiscal years 2000, 2018, and 2019.
Total Flying Hours
Total flying hours fleetwide were calculated by adding up the hours for all manned Army aircraft and for specific categories of aircraft.
Flying Hours per Aircraft
CBO determined the average number of hours each aircraft flew each year by dividing total flying hours by the number of Army aircraft.
Relationships Between Aircraft Ages and Their Availability and Use
In earlier reports, CBO displayed the relationships between the ages of individual aircraft and their availability rates and use. The agency applied the same analytic technique to the Army’s large helicopter fleets. The curves shown below reflect past availability and use. They do not project future availability or use, which will also be influenced by factors other than age.
Effects of the Pandemic on Aircraft Availability and Use
In early 2020 (the onset of the coronavirus pandemic), the availability of Army aircraft fleetwide increased, but flying hours per aircraft decreased sharply. That pattern parallels what happened with the availability and use of aircraft in the Air Force and the Department of the Navy.
In the GCSS-Army Enterprise Aviation data system, months end on the 15th. Hence, March 2020 ended March 15, 2020, largely before the pandemic’s impact was observed in the United States; April 2020 (ending April 15, 2020) proved to be the lowest month of Army aircraft use during the pandemic. Because UASs do not appear in the data system until January 2021, they are not considered in this analysis.
Effect on Availability Rates
Availability of Army aircraft peaked in May 2020. Two factors may account for the increased number of aircraft that were available then. First, the Army was flying its aircraft for fewer hours, so more spare parts may have been available to complete maintenance. Second, fewer flying hours may have reduced the chances that available aircraft would experience problems and need repairs.
Effect on Flying Hours per Aircraft
To evaluate the effect of the pandemic on flying hours, CBO computed five-year monthly averages of flying hours per aircraft for the years preceding the pandemic. (CBO averaged the data over five years because monthly flying hours may vary considerably from year to year.) The agency compared those averages with the corresponding months in fiscal years 2020 and 2021.
About This Document
This report was prepared at the request of the Chairman and Ranking Member of the House Armed Services Committee. In keeping with the Congressional Budget Office’s mandate to provide objective, impartial analysis, the report makes no recommendations.
Edward G. Keating and Nikhil Bhandarkar prepared the report with guidance from David Mosher. David Arthur and Jared Jageler provided assistance. F. Matthew Woodward fact-checked the report. Jennifer DiMascio of the Congressional Research Service provided comments on an earlier draft. The assistance of an external reviewer implies no responsibility for the final product; that responsibility rests solely with CBO.
Mark Doms, Jeffrey Kling, and Robert Sunshine reviewed the report. Christine Bogusz edited it, and R. L. Rebach created the cover illustration and graphics and prepared the text for publication. The report is available at www.cbo.gov/publication/60313.
CBO seeks feedback to make its work as useful as possible. Please send comments to communications@cbo.gov.
Phillip L. Swagel
Director
September 2024