Full operating capability (FOC) has been declared for the 25 AW101-based Commando Merlin MK3/Mk3a helicopters upgraded to the ‘ship-optimised’ Mk4/4a standard, Leonardo UK announced on 29 January 2025.
In total, the Merlin Life Sustainment Programme (MLSP), overseen by the UK Ministry of Defence’s Defence Equipment & Support organisation (DE&S) and conducted by Leonardo UK, saw 19 Mk3 and six Mk3a Commando Merlins upgraded to the Mk4/4a standard. Key original upgrades to the aircraft included a new folding main rotor head and folding tail, which allows two of the aircraft to fit on just one of the lifts on a Queen Elizabeth-class aircraft carrier, and an improved defensive aid suite with a system that warns against and locates hostile laser-guided weapons.
Following delivery of the final aircraft conversion in 2022, DE&S oversaw retrofit-after-delivery activity that included an integrated mission planning system installation and integration of synthetic training equipment.
The declaration of FOC confirms achievement of the Royal Navy (RN) requirement and full acceptance of the Commando Merlin Mk4/4a fleet, which can now operate from a greater range of RN ships, including its aircraft carriers, amphibious assault ships, Type 23 frigates, Type 45 destroyers and Royal Fleet Auxiliary vessels.
The Commando Helicopter Force (CHF) provides air manoeuvre support to 3 Commando Brigade Royal Marines and other UK forces. It also supports the RN’s Carrier Strike Group and can conduct search-and-rescue, counter-narcotics, anti-piracy, maritime security and hurricane relief support operations if required.
The upgrade has enabled Merlin to be a more effective component in the future conduct of littoral manoeuvre operations, allowing the CHF to generate, sustain and field a more modern aviation capability.
In addition to the operational benefits, the aircraft now share a higher commonality across all marks of Merlin with an upgraded cockpit and avionics suite that provides efficiencies within supply chains, effective maintenance cross-platform knowledge and training, while also enabling further interoperability when deployed.
Captain Neil Mathieson, RN Merlin DT Team Leader, said: “The key difference between the Mk3/Mk3a and the new variant is the fact that the Mk4/Mk4a has been fully ‘ship optimised’ to allow it to in embark and more efficiently operate from Royal Navy vessels. This means that the Mk4/Mk4a aircraft are globally deployable for all maritime operations.
“There have been significant changes to enable this, including a new folding main rotor head and folding tail,” Capt Mathieson exaplained. “In addition, a brand-new suite of avionics has been integrated and obsolescence removed, aligning the cockpit to the Mk2 and extending the life of the platform to 2030.”
Clive Scott, senior vice president for UK business at Leonardo Helicopters UK, added, “Our workforce is proud to have delivered these upgrades for the Royal Navy Merlin fleet from our site in Yeovil: the Home of British Helicopters. Decades of investment in the site have ensured that we have the highly specialised design skills onshore, meaning we can modify helicopters to UK specifications and help preserve our nation’s freedom of action and operational independence.
“The AW101 sets the standard for maritime operations and, as well as being one of the UK armed forces’ core helicopters, has been acquired by allies including Japan, Italy and Poland,” said Scott. “Our export customers benefit from continuous investment in the platform, as well as their ability to interoperate with the Royal Navy.”
The synthetic trainer includes two new pilot simulators, a procedures trainer and a rear crew training device, employing augmented-reality systems. For the first time this is co-located at RNAS Yeovilton with the CHF, providing a step change in training capability for new aircrew and front-line mission training.
