The UK Ministry of Defence (MoD) is exploring the potential of adopting a variant of the General Atomics MQ-9B SkyGuardian unmanned aerial system (UAS) to replace the Royal Navy’s troubled Merlin HM2 Crowsnest helicopters in the critical Airborne Early Warning and Control (AEW&C) role. This development, if realized, could fundamentally reshape how Britain projects naval air surveillance and defence capability from its flagship Queen Elizabeth-class aircraft carriers.
The proposal, first publicly acknowledged on May 19, 2025, emerged following a formal inquiry by Conservative MP Ben Obese-Jecty to the Secretary of State for Defence about the feasibility of using the MQ-9 platform aboard Royal Navy carriers. Defence Minister Maria Eagle responded, confirming that through the UK’s involvement in the MQ-9 International Cooperation Support Partnership, the Royal Navy had established that the platform could be modified for carrier operations.
“As such, the MQ-9 is being considered as a candidate for the RN’s requirement for Carrier Strike Airborne Early Warning following the planned withdrawal of the Crowsnest Airborne Early Warning system,” Eagle stated.
On April 9, 2025, the Ministry of Defence issued a formal Request for Information (RFI) titled “Carrier Strike Airborne Early Warning Initial Market Engagement.” Its purpose was to assess industry capability to deliver an AEW&C system operable from Queen Elizabeth-class carriers and capable of providing continuous 24-hour coverage.
The desired system must offer persistent surveillance of air and surface threats, such as anti-ship cruise missiles and hostile aircraft, ensuring rapid detection and response coordination for the Carrier Strike Group (CSG). Due to the growing unreliability of the Crowsnest, this requirement is pressing.
The Royal Navy has historically depended on helicopter-based AEW systems, starting with Sea King variants developed in a crash program following the Falklands War. However, Crowsnest — the system that succeeded the Sea King ASaC7 — has failed to meet expectations since its inception in 2018.
Designed as a modular system to be retrofitted onto the Merlin HM2 anti-submarine warfare helicopters, Crowsnest was intended as a cost-effective and flexible solution. But by late 2023, costs had ballooned from the original £269 million to over £425 million. Full operational capability (FOC) has still not been reached, even after being deployed on two carrier strike missions.
The core of the Crowsnest’s problems lies in its integration of the legacy Searchwater 2000 radar and the Cerberus mission system. Persistent software issues have reportedly hampered radar performance, reducing mission effectiveness and leaving fleet commanders dissatisfied.
With its planned out-of-service date of December 31, 2029, Crowsnest risks becoming obsolete before it has ever fully worked, thus creating a potential capability gap just as geopolitical tensions escalate.
In contrast to helicopter platforms, the MQ-9B offers several advantages for the AEW&C mission. As a Medium Altitude Long Endurance (MALE) UAS, it boasts a service ceiling of 40,000 feet — more than double the Merlin’s 15,000-foot limit. This altitude increase translates into a significantly larger radar horizon, boosting early detection range.
Additionally, the SkyGuardian can loiter for over 24 hours, surpassing any rotary-wing aircraft. Its long endurance makes it ideal for the kind of persistent, wide-area surveillance essential to modern naval operations.
However, transitioning from helicopter to UAS also brings fundamental changes to how AEW&C missions are crewed and coordinated. Unlike helicopter platforms where mission crews are onboard, UAS operations would place mission controllers and radar analysts either shipboard or ashore, relying on secure data links to feed real-time intelligence to airborne assets and command staff.
This approach requires substantial investment in carrier-based control infrastructure and robust communications systems to ensure seamless data flow, especially in contested environments.
A major milestone in demonstrating the feasibility of carrier-based drone operations occurred on November 15, 2023, when a modified MQ-1C Grey Eagle variant, known as Mojave, successfully conducted takeoff and landing trials on HMS Prince of Wales. This STOL (Short Take-Off and Landing) UAS, developed by General Atomics, features a wider wingspan and high-lift wings to facilitate operations from short, unassisted flight decks.
The success of the Mojave trials laid critical groundwork for considering the SkyGuardian for carrier deployment. While the Mojave itself may not be the final platform, its achievements have convinced the Royal Navy that a drone-based AEW&C system is technically viable.
Enter the Protector RG Mk1, the UK’s version of the MQ-9B SkyGuardian. Already in Royal Air Force service as of 2024 with No. 31 Squadron “The Goldstars,” the Protector is equipped for autonomous takeoff and landing, a key feature for carrier-based operations.
It also includes detect-and-avoid capabilities, enabling operations in civilian airspace. Armed with Brimstone II and Paveway IV precision-guided munitions, and fitted with high-definition electro-optical and infrared sensors, the Protector offers considerable versatility beyond the AEW&C role.
Protector’s extended loiter time of up to 40 hours, combined with the potential addition of a modern air surveillance radar and a STOL kit like Mojave’s, positions it as the front-runner in the race to replace Crowsnest. The platform could be adapted quickly, offering a relatively low-risk, off-the-shelf solution within the £500 million to £1.5 billion budget estimate.
Queen Elizabeth-class carriers, unlike their American or French counterparts, do not have catapults. This precludes the use of heavier fixed-wing AEW&C aircraft like the E-2 Hawkeye. The SkyGuardian’s STOL potential sidesteps this issue, but it still faces challenges.
Chief among these is radar payload. Helicopter-based radars like the Searchwater have significant weight. Adapting such systems to a drone airframe without compromising takeoff capability or flight performance will require engineering ingenuity.
Furthermore, while Protector can autonomously operate from fixed airfields, carrier operations are inherently more complex. Rough seas, limited deck space, and precise timing demand an even higher degree of automation and resilience in both hardware and software.
To meet this challenge, upgrades to the carriers themselves are under consideration. Installation of lighting arrays for Short Rolling Vertical Landing (SRVL) is already underway, intended primarily for F-35B fighters but potentially adaptable for UAS recovery.
The urgency to find a solution is not lost on Royal Navy planners. The 1982 Falklands War is a cautionary tale. At the time, the UK lacked any organic airborne early warning capability, leading to devastating surprise attacks by Argentine forces. In response, two Sea King helicopters were quickly converted with radar pods into AEW aircraft.
Though too late for the conflict, these ‘baggers,’ as they were known, became the progenitors of the Royal Navy’s AEW lineage. The crash development proved what could be achieved under pressure, a sentiment echoed in today’s renewed urgency.
Longer-term solutions have been proposed, such as Project Vixen, a stealthy catapult-launched drone akin to Australia’s MQ-28 Ghost Bat. However, this project has been deprioritized amid more immediate needs, with the MoD focusing instead on practical, near-term solutions.
With Protector and SkyGuardian now under the spotlight, the next five years will be decisive. The Royal Navy has until 2029 to avoid a critical gap in its surveillance capabilities. That’s a tight timeline for the type of development and integration required.
But history shows that the Royal Navy, when backed into a corner, can innovate rapidly and effectively. The question is whether today’s defence industry and procurement systems can match that same urgency.
The consideration of the MQ-9B SkyGuardian as a potential replacement for the Royal Navy’s AEW&C helicopter fleet reflects both technological ambition and operational necessity. Amidst rising global tensions, a reliable and persistent early warning system is not optional—it is essential.
