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The largest aircraft in the United States Air Force's arsenal isn't the Boeing VC-25 (based on the 747) used for presidential transport, but rather the less glamorous Lockheed C-5 Galaxy. The C-5 is of a similar vintage as the 747 and was designed specifically as a military freighter, having only ever served for the USAF across the 56 years since its introduction. Despite its age, the USAF is firmly committed to the C-5 in its long-term fleet plan and will upgrade these aircraft.
The C-5 remains the largest aircraft ever operated by the USAF, and it fulfills the branch's requirements for a large strategic airlifter capable of carrying outsized cargo and featuring intercontinental range. The C-5 has been in service since 1970, and yet the USAF doesn't see the need for a replacement yet. Instead, it's pouring $143 million into refreshing the Galaxy's software systems, while also working to improve the C-5's physical structure. With these projects, the C-5 will end up serving until 2050.
An Overview Of The Lockheed C-5 Galaxy
The Lockheed C-5 Galaxy was the USAF's selection for its heavy logistics system request, first issued in 1964. The USAF narrowed down the submissions to proposals from Boeing, Douglas, and Lockheed for the airframes, along with engines from General Electric and Pratt & Whitney.
While the USAF preferred Boeing's design overall, Lockheed's proposal promised the lowest total costs, and the USAF selected what would become the C-5 Galaxy to be paired with the General Electric TF39. Designed to carry huge payloads with a massive cargo hold, the C-5 remains the largest aircraft operated by the US military. It's a high-wing quadjet with a T-tail, and it can carry up to 127.4 tons of payload.
Inside, the Galaxy has enough space to carry up to 36 463L master pallets while also carrying up to 73 passengers on its upper deck. With a length of 247 feet one inch (75.31 meters), a wingspan of 222 feet nine inches (67.89 meters), and a maximum takeoff weight of 381 tons, it remains the largest American plane ever put into service. Lockheed delivered 81 examples of the original C-5A variant to the US from 1969 to 1973.
The company later restarted production in 1986 to deliver 50 examples of the improved C-5B variant until 1989. In addition, two C-5As were modified with larger cargo holds and were redesignated as the C-5C. In the 2000s, the USAF began upgrading its existing C-5 fleet with the General Electric F138 (based on the CF6), along with additional upgrades. One C-5A, 49 C-5Bs, and both C-5Cs were upgraded to the C-5M Super Galaxy specifications.
The Latest Upgrade Program For The C-5
Earlier in July 2026, the USAF awarded Lockheed Martin a $142.9 million sole-source IDIQ contract to provide software sustainment services for the C-5. In essence, the manufacturer will develop and issue software updates while also maintaining the digital systems that ensure the aircraft meets safety and performance standards.
Lockheed Martin will keep running the infrastructure needed to develop new software for the aircraft, operating two facilities (one in Marietta, Georgia, and one in Greenville, South Carolina) for the work. The contract will cover ongoing engineering and technical support to ensure the C-5's reliability, catching issues before they escalate in severity.
It will also ensure that the C-5 still functions with modern ATC systems, navigation software, and the United States Air Force's digital infrastructure. Given that the C-5 has been around for well over 50 years, it's crucial to ensure that the aircraft can function safely and effectively for the next few decades, and updating the aircraft's code is crucial to achieving this. The US Air Force expects Lockheed Martin's efforts to continue until May 2032.
The IDIQ (indefinite-delivery, indefinite-quantity) sets a spending cap for the program without needing to commit to a timeline or the scope of the work. Rather, this type of project gives flexibility to perform specific tasks as needed. The sole-source nature of the contract means that no other manufacturers were invited to bid, which makes sense as Lockheed originally developed the C-5 Galaxy and is therefore familiar with the type.
The Other Active C-5 Support Contract
In 2025, the USAF awarded a $211.3 million IDIQ sole-source contract to Lockheed Martin for physical support and maintenance on the C-5M fleet. The contract included $34.9 million obligated at the award and will run until September 2030. Once again, Lockheed Martin was the only party invited to the bid, as no other company could replicate Lockheed Martin's knowledge and familiarity with the C-5 Galaxy. As such, it was the only choice for the C-5 structural contract.
This project essentially covers structural integrity, functional systems integrity, corrosion prevention, and deficiency investigation. This will ensure that the planes themselves are physically airworthy and can still be maintained cost-effectively. The hardware contract was notably issued separately from the more recent software project, showing how important software and digital systems have become to modern military aviation.
This means that the teams working on each project can focus more thoroughly on the covered areas compared to if it were a single contract. With the USAF's goal of operating the C-5 for the next few decades, the hardware contract is important to ensure the aircraft can be flown easily and reliably.
While the program itself dates back to the 1960s, the actual planes flying today were delivered from 1986 to 1989. They're aging, but far from the oldest planes currently serving for the USAF, and they have lots of life left. While it's uncommon, there are older commercial airliners and freighters in service today.
Why The C-5 Galaxy Will Remain In Service For So Long
Aircraft can fly nearly indefinitely if maintained well. In the civilian world, there are general aviation planes still being flown that date back to before the Second World War, while some large airlines continue to fly Airbus A320s, Boeing 737s, 747s, 757s, and 767s that are over 30 years old. Many freighters are even older.
The reason why airlines tend to retire planes after 20, 30, or 35 years is that maintenance becomes more expensive, while newer aircraft types burn significantly less fuel, creating regular retirement cycles in the commercial aviation industry. The US military, however, doesn't care that much about fuel burn. Instead, the priority is usability, functionality, and ease of maintenance.
While operating costs, including maintenance and fuel, do still matter, it's less of a priority for the US armed forces, and it also has different benchmarks for these costs compared to an airline. The maintenance bill for a 40-year-old C-5M Super Galaxy would be astronomical on an airline's balance sheet, but the same figure is more modest for the USAF. Advances in military aviation technology have primarily been focused on areas like stealth or weapons technology.
For the C-5, which has a relatively undemanding mission role, the aircraft functions perfectly fine, meaning that there's not a huge benefit in requesting a cleansheet program. The USAF isn't in need of an aircraft larger or more capable than the Super Galaxy, while it already flies smaller, cheaper freighters in the form of the C-17 and C-130. Therefore, the C-5 will continue to serve with the USAF, mainly because it simply works.
The Replacement For The C-5 (And The C-17)
As previously mentioned, an aircraft's operating and maintenance costs hold less importance for the USAF compared to an airline, but it doesn't mean that the costs are zero. The USAF previously stated that the C-5 Galaxy would remain in service throughout the 2040s and most recently extended this timeline to 2050, by which point the youngest C-5M would be over 60 years old. What's more, these planes are massive and technically complex, with four engines that will be outdated by 2050.
The USAF plans to begin operating a new strategic airlifter in the 2040s, currently referring to the hypothetical platform as the NGAL (next-generation airlift). Curiously, it'll be used to replace the C-5 as well as the Boeing C-17 Globemaster III, functioning as a two-for-one project. The branch is currently in the early stages of determining its requirements for the NGAL, but is currently focusing on agility, survivability in higher-threat environments, and improving defensive capabilities.
Currently, the US Air Force is looking to procure one aircraft for the NGAL to replace the C-5 and C-17, which raises questions as these aircraft are extremely different from one another. Not only is the C-17 smaller than the C-5, but it also has short-field and rough-field capabilities. If the USAF goes ahead with one aircraft for the NGAL, it'll likely blend elements of both planes but deprioritize other features offered by the C-5 or C-17, and will likely be sized between the two.
