The Royal Navy’s Merlin helicopter fleet – bearing a heavy load

Glossy MoD publicity may give the impression the Fleet Air Arm is in rude health with several new types of aircraft coming into service to replace ageing veterans. A new generation of aircraft are indeed being delivered but the actual number of helicopters in RN service will have declined dramatically by 57% (From 194 to 83) in the decade between 2009 and 2019. The reduction in helicopter numbers across all the UK forces is particularly perverse and goes against the repeated the clear lessons from operations in the Falklands, Iraq and Afghanistan that you can never have enough helicopters. During 10 years in Afghanistan UK helicopters alone accumulated a staggering 138,654 flying hours, transporting around 700,000 passengers, 25,000 tonnes of cargo, and 13,000 casualties.

The individual aircraft maybe more capable but the total number of helicopters owned by UK armed forces will have roughly halved between 2009 and 2019.

UK Helicopter numbers

Based on figures from
(Mk 3/5 Search & Rescue SeaKings retire in 2016)

Helicopters are exceptionally maintenance intensive and have hundreds of moving parts, the failure of just one can cause the loss of the aircraft. Even modern helicopters with sophisticated self-diagnosis systems such as the Merlin will require an average of 2 hours maintenance for every hour flying. A Merlin will need major overhaul every 600 flying hours which can take around 2 months. As helicopters age, the time spent in the workshop relative to flying hours increases further. This maintenance overhead makes the number of airframes particularly critical to maintaining appropriate levels of availability. The elderly Mk7 ASaC SeaKings, which will remain in service until 2018, now require ten times that of a Merlin, 20 hours of maintenance for every 1 hour flown.

‘The flying frigate’- Merlin HM1 and HM2

The Merlin came into service under something of a cloud criticised as late and expensive. (Sound familiar?). However the aircraft has matured into a fine anti-submarine aircraft. A Type 23 frigate using its towed array sonar in combination with a Merlin represents just about the best ASW solution available in the world, besides hunting with another submarine. The Merlin was initially conceived as a dedicated Cold War submarine hunter to replace the Sea King HAS 5 & 6. In keeping with the more diverse roles of the Navy today, the ASW Merlins also carry out a wide range of other tasks including reconnaissance, general transport and load-lifting.

The £1.15Bn Merlin Capability Sustainment Plus (MCSP) upgrade of the whole fleet from HM1 to HM2 standard has delivered 24 aircraft already (actually £2.4M below budget) and the programme will be complete by the end of this year. Important changes include major improvements to crew ergonomics, computers and avionics, radar and sonar. The recent upgrades have not only improved ASW capability but will provide wider utility in other roles and scenarios. A separate programme to equip the Merlin with an updated defensive aids system equipment, ballistic protection and an electro-optical/infrared sensor will be completed in October 2015.

44 Merlins were delivered to the RN between 1997 and 2002. Two aircraft were lost in accidents but 12 have been put in deep storage and although there is an option in the MCSP contract for ‘a further 8’ to be upgraded to HM2 standard, it seems unlikely. These aircraft would seem the obvious candidates to be fitted with the Thales Cerbus system for the ASaC role (more on that later) but lack of funds is preventing this. It is not just the cost of upgrading the aircraft that has to be considered, but the training and retention of specialist aircrew.

Struggling to keep hold of personnel, the RN has recently had to offer bonuses ranging from £40K – £100K to experienced aircrew prepared to sign on for a further 5 years service.

The 30 Merlin HM2s have their work cut out with around half of them required for front-line duties at any given time. The active QE class aircraft carrier will hope to embark at least 6 Merlins to form a credible ASW force that can keep at least 1 or 2 aircraft flying 24/7 when on operations. Assuming there are around 3 Type 26 frigates dedicated to ASW duties, they need an aircraft each. The Lynx Wildcat is an alternative and capable aircraft but lacks the endurance and dipping sonar that make the Merlin so potent in the ASW role. Without Maritime Patrol Aircraft, several Merlins are also needed in Scotland to protect the ballistic missile submarines from foreign intruders. Like so many RN assets, there is no strength in depth to provide additional aircraft for a surge deployment or to replace combat losses.

The HM1 and HM2s have been very active in other roles, 3 were sent on Operation Gritrock in 2014 (stripped of ASW equipment) and used as transport aircraft, flying personnel and stores around Sierra Leone in the successful fight against the Ebola disease. 3 more Merlins from 814 NAS were dispatched to the Mediterranean in the summer of 2015 to participate in Operation Weald. Based in Italy, they operated from HMS Bulwark and other EU vessels providing surveillance and guiding vessels to the location of migrant boats in need of rescue. Although quite capable of these diverse roles, working the airframes so hard now will require additional funds to keep them airworthy in future.

‘Eyes of the fleet’ – Airborne Surveillance and Control

The MoD has spent more than 15 years and £27 Million on the CROWSNEST project examining options replace the 13 ASaC Sea Kings that provide critical airborne early warning for the fleet. Finally in May 2015 it was announced that the updated Thales Cerberus system has been selected. In stark contrast to this lumbering process, the original helicopter-borne AEW system was developed on a shoestring in a matter of weeks and rushed into service in the wake of Falklands War. The CROWSNEST decision was presented as a “triumph” because the timetable has brought forward slightly so the system should be available to go to sea with HMS Queen Elizabeth when she is operational by 2020.

The 13 ancient Sea Kings dedicated to the ASaC role will eventually be replaced by a number of ‘kits’ (probably around 10) that will be fitted to existing Merlin HM2s. In theory the kits can be removed from the aircraft so it can return to the ASW role within a few hours. This may appear to be useful flexibility but the carriers will need ASaC capability most of the time and its a task requiring trained crews with specific skills. Having to switch precious ASaC platforms to ASW (or vice versa) is far from ideal. The QE carriers also have plenty of space so there would not be an issue with embarking additional aircraft.

The chosen Thales solution will probably be adequate but it is the cheapest and lowest risk option, simply a development of the existing radar system and no great leap in capability. Hopes of a V-22 Osprey-based option which would offer much greater range and endurance were always unlikely, given the huge development cost. Perhaps the biggest challenge for the project is to usefully integrate the new system with the F35Bs which have a very sophisticated and networked sensor capability of their own.

The ‘Junglies’ upgrade a mixed blessing – Merlin HC3, Hc3i and HC4

The Commando Helicopter Force will complete the transition from its much-loved, but antique Sea Kings to Merlin HC3s in 2016. The Merlin is faster, has better range and greater capacity than the Sea King. However these aircraft are very much second hand, in service since 2001 with the RAF that has already run them hard, deployed operationally in Bosnia, Iraq and Afghanistan. The 25 HC3s are decent battlefield helicopters but not yet suitable for shipboard operations. They must undergo a major marinisation and upgrade programme (to HC4 standard) which will include folding rotors and similar avionics to the HM2. The first HC4 will be delivered in 2018 and the programme will not complete until at least March 2020. In the meantime 7 interim aircraft (known as HC3i) will have basic changes made, most importantly folding rotors. These aircraft are being delivered to the RN between October 2015 and April 2016. Some HC3s have been recently been trialled at sea aboard HMS Ocean but without folding rotors they cannot be struck down into the hangar, limiting their usefulness. The 7 HC3is will not be ready in time for deployment on the Cougar 2015 amphibious exercise which is about to commence. As the CHF gets into its stride operating its newly acquired aircraft, three HC3As have recently been shipped to the US and deployed to California, USA on exercise Black Alligator. The HC3As were originally Danish aircraft bought in haste by the MoD to boost aircraft numbers available for use in Afghanistan and are slightly differently configured to the HC3s.

New aircraft were never an option for the Junglies who had to trade 37 very old Sea Kings for 25 well-used Merlins, mostly unfit for deployment at sea until 2020 when the glacially slow upgrade programme is completed.

  • Merlin Concoles

    New operator consoles on Merlin HM2 which will also display data from the Searchwater airborne surveillance radar when fitted

  • Merlin HC3 in formation with the Sea King Mk 4 it is replacing

    Merlin HC3 in formation with the Sea King Mk 4 it is replacing

  • CGI depicting Merlin HM2 configured with Cerberus radar

    ‘The eyes of the fleet’ CGI depicting Merlin HM2 configured with updated Searchwater radar

  • W-4 Solo unmanned helicopter conducted simulated landings on moving vehicles

    W-4 Solo unmanned helicopter conducted simulated landings on moving vehicles

The UK recently concluded the Rotary Wing Unmanned Aerial System (RWUAS) Capability Concept Demonstration (CCD) programme, designed to help the RN make decisions about future unmanned helicopters. A full size  unmanned W-4 Solo conducted simulated landings on moving vehicles, although the planned trials at sea never took place due to “a lack of available Royal Navy platforms”. Unmanned rotary aircraft may offer a partial solution to the shrinking helicopter fleet. They can be procured more cheaply and in much larger numbers and with less manpower training involved. Whether an unmanned helicopter could ever fully replicate the great utility of a manned platform like the mighty Merlin remains to be seen.