The U.S. Navy’s MQ-25 Stingray drone-refueler program has hit another snag, highlighting ongoing challenges in getting the first fixed-wing unmanned aircraft into service for operations from a nuclear-powered aircraft carrier.
The Pentagon’s Director, Operational Test and Evaluation (DOT&E) recently reported that the official “Milestone C” decision has been delayed beyond its initial timeframe. Milestone C is a critical step in U.S. Weapons programs, authorizing a transition from development to production and operational deployment, and validating that the system is mature and reliable under real-world conditions.
Originally anticipated for fiscal year 2023, the DOT&E has indefinitely postponed this key milestone due to industrial delays and unusable data.
Boeing Faces Renewed Scrutiny?
Production issues, particularly with some subcontractors, and delays in the availability of test aircraft are at the heart of the difficulties.
Yet, the primary obstacle is methodological. The Pentagon believes the available data for evaluating the system isn’t representative of an operational aircraft. Much of the data comes from a demonstrator developed and operated by Boeing, which differs significantly from future production models in internal structures, fuel systems, communication architectures, and ground control systems.
Moving into production requires testing under conditions closely resembling real-world use, with equipment matching the final configuration. Currently, the DOT&E believes those conditions haven’t been met.
This DOT&E assessment is another setback for Boeing, which has faced significant challenges in recent years with technical reliability and assembly quality across numerous programs, stemming from management issues within the company.
In the civilian sector, the 737 Max disasters and qualification delays for the latest 777X are well-documented. In the space sector, the Starliner capsule program, intended to compete with SpaceX’s Crew Dragon, continues to experience delays and major technical defects.
On the military side, the KC-46 aerial refueling program has as well been plagued by technical problems, recently being deemed less effective than the aircraft it’s meant to replace, prompting the Air Force to pause further purchases until Boeing addresses the identified defects. The Super Hornet Block III fighter program also faced setbacks, with the cancellation of the CFT external fuel tank integration due to reliability issues during aircraft carrier operations – a disappointment for the Navy, as the CFTs were a key component of the Block III and aimed to address the range limitations of carrier-based fighters, a challenge also addressed by the MQ-25 Stingray.
Uncertain Timeline Ahead
Interestingly, the DOT&E appears to share some responsibility for the Stingray evaluation. Facing industrial delays, the Navy agreed in 2022 to evaluate Milestone C with a Boeing prototype rather than an aircraft representative of the production series. While this isn’t uncommon, it only works if the prototype or demonstrator providing the evaluation data closely resembles the final product – which isn’t the case with the MQ-25.
the program remained stuck in its development phase, extended by the need to produce representative aircraft and conduct a full operational assessment. The first Engineering Development Model aircraft were only delivered in the spring of 2025, with flight tests expected this year.
The first MQ-25A representative of the production series completed its initial taxi tests in January and could soon take flight, providing the precise data needed for Milestone C, and series production and full operational qualification of the drone-refueler.
These delays also represent a broader shift in the program’s schedule. The first flight of a representative aircraft, expected in the coming weeks, was initially planned for 2024, then 2025.
A Key Program for U.S. Naval Aviation
These difficulties come as the MQ-25 is a crucial program for the evolution of U.S. Carrier air groups. Designed as a refueling drone, the Stingray aims to free F/A-18E/F Super Hornet fighters from these refueling missions, allowing them to focus solely on combat. This translates to a greater immediate strike capability for carrier air groups, as well as increased longevity for the Super Hornet fleet, which won’t have to expend its potential on in-flight refueling.
Beyond this logistical function, the MQ-25 is also expected to play a key role in integrating unmanned systems into naval operations, with secondary capabilities in intelligence, surveillance, and reconnaissance (ISR). As such, it’s often presented as a first step toward a carrier-based aviation model more broadly based on cooperation between manned and unmanned platforms.
The MQ-25 program is being closely watched by the French Navy, which is considering equipping its future *France* aircraft carrier with fixed-wing drones for both combat missions alongside the Rafale F5 and the future NGF, as well as for in-flight refueling missions.
A Slower Ramp-Up Than Expected
The current slowdown doesn’t invalidate the program’s fundamental goals, but it delays their realization. It underscores the technical and industrial challenges associated with introducing complex drones into the particularly constrained environment of operations from an aircraft carrier.
In the short term, the U.S. Navy’s priority will be to rebuild a credible testing base, relying on aircraft and systems representative of the final product – a crucial condition for reaching the stage of large-scale series production.
these difficulties serve as a reminder that, despite the ambitions surrounding unmanned carrier aviation, the transition to these new operational models remains a long, uncertain process heavily dependent on industrial maturity.
© An article by the Mer et Marine editorial team. Reproduction prohibited without the consent of the author(s).
