Monday, 21 March 2016

MACs and Jeep Carriers: A Useful Lesson From History

"We must assume that the battle of the Atlantic has begun... Extreme priority must be given to fitting out ships to catapult or otherwise launch fighter aircraft against bombers attacking our shipping. Proposals should be made within a week."
-Winston Churchill, March 6th 1941

At the height of the Second World War Britain, under immense pressure from Germany's U-Boat campaign, converted sixty one merchant vessels into auxiliary aircraft carrying ships. While thirty five were "CAM" ships (Catapult Aircraft Merchantman) equipped with a single last-ditch catapult launched Hurricane fighter, nineteen were fully-fledged flat topped "MAC" ships (Merchant Aircraft Carrier) capable of launching and recovering aircraft. Over the course of the War the Royal Navy also operated a total of forty four light "escort carriers". These ships were made necessary because of a number of factors but, fundamentally, they were built because the RN needed to close the "black gap" (the area in the mid-Atlantic beyond the range of land based anti-submarine aircraft where U-Boats concentrated their efforts). The presence of MACs and escort carriers helped to finally turn the tide in 1943 and ensured that Germany's 1944/45 commerce raiding campaigns would fail.

It's certainly worth asking why these ships were successful in their de-facto service with the Royal Navy, to the extent that it is claimed not a single merchant ship was lost from a convoy defended by a MAC. They certainly weren't very good aircraft carriers, even the largest couldn't operate more than four Fairey Swordfish biplanes and the aviation facilities were quite rudimentary. While escort carriers were certainly better than MACs as aviation ships, some were able to carry up to 24 aircraft and all had superior purpose-built aviation facilities, they achieved substantial tactical and operational effect for the same reason as the smaller civilian conversions. The reason for their success can be summed up in a single word: presence. While the air groups were small, especially when compared with the RN's fleet carriers, the MACs and escort carriers were comparatively cheap and available in large numbers. This meant that they could be used for convoy protection, as well as many other duties that the handful of hard-pressed large fleet carriers were too busy to perform. While around three quarters of the Royal Navy's escort carriers were built in the United States and loaned to Britain under the terms of the Lend Lease act, most were extensively modified by the RN, with all having their provisions for damage control improved and brought up to the RN's higher standards before entry into service.

So, what is the modern relevance of Britain's Second World War experience with MACs and escort carriers? Now we are, of course, no longer facing the threat of hordes of rudimentary diesel-electric submarines attempting to strangle our maritime communications. However, the fundamental lesson learned from that wartime experience was that inexpensive merchant-conversions, and aviation ships that exist below the capability of a fleet carrier, can enhance their larger cousins' availability by covering a wide range of low-end activities. In the Pacific the US Navy used its "Jeep" carriers (escort carriers) for a wide range of support and front-line activities, from transporting aircraft to launching strikes against Japanese forces in support of amphibious operations. While the ships themselves were generally unimpressive this was largely irrelevant, as their fighting power came from the aircraft they carried rather than the ships themselves. What we might now refer to as providing combat capability through "off-board systems".

Skip forward to the twenty first century and we find that aviation ships, below the level of a fleet carrier, continue to be valuable additions to many navies around the world. They come in a vast variety of shapes and sizes and, with modern helicopters, almost any large merchant ship can be converted into a somewhat capable aviation platform "on the cheap". RFA Argus, the UK's floating military hospital, was originally taken up from trade by the MoD in 1982 as the Contender Brezant before being purchased outright in 1984 and into an aviation training ship. She entered service in 1988. In this role she could carry and operate around six RN, Army Air Corps or RAF helicopters up to and including the largest rotary wing aircraft in UK service, the CH47 Chinook. Alternatively she could transport, although not operate, up to twelve Harrier-type VTOL aircraft. In a very real sense Argus, in her "aviation training" configuration, was the modern embodiment of the MAC ships of the Second World War. Her initial conversion proved extremely cost effective, costing only £45mn (~£120mn in 2016 prices). She also had the added benefit of only requiring a fifth the manpower of an Invincible class light carrier, just over half of which were actually Royal Navy personnel; with the rest being made up of RFA merchant sailors.

RFA Argus, the "modern MAC", has proved to be an incredibly valuable asset 
over nearly three decades of hard service.
Since her formal entry into service with the RFA in 1988 Argus has consistently been a busy ship. During the 1990-91 Gulf War she received her second major conversion, adding extensive medical facilities to enable her to act as the UK "Primary Casualty Receiving Ship" (or PCRS). She sailed or the Gulf with four Sea-King helicopters embarked, which aided in mine-clearance operations once she arrived in theater. In 1992 she deployed to the Adriatic, again with Sea Kings embarked, in support of the UK's contribution to the UN Protection Force in Yugoslavia. In 1997 she deployed to the West coast of Africa to evacuate UK nationals from the Congo. She was part of the UK's national amphibious task group that deployed to both Sierra Leone in 2000 and Iraq in 2003. She underwent a major life extension in 2009 before being deployed to the Mediterranean, ready to evacuate UK nationals from Libya in 2011. Later that year she was assigned to the counter-piracy effort in the Gulf of Aden. Her most recent activities have included support for UK overseas territories in the Caribbean and aiding in the fight against Ebola in Sierra Leone.

It is notable that Argus, like the Second World War MAC, has filled the gap that exists below the space occupied by high-end aviation platforms designed for intensive war fighting. Indeed, the only time that Argus was trialed in such a role (she was used as a makeshift helicopter carrier during the international intervention in Yugoslavia) she did not perform well. However, as an auxiliary aviation support platform, used initially for training and later for a range of defence and security activities below the level of war, she has proved herself invaluable. Indeed, it's possible that the lessons learned from RFA Argus contributed to the development of the Bay class auxiliary landing ships, with their distinctive flat aviation decks aft of the main superstructure.

When her procurement, conversion and operational costs are tallied and compared to her service record it becomes quite clear that Argus has been, and continues to be, excellent value for money. She is the ultimate vindication of the relevance of the MAC concept for the 21st century. Considering this, it is concerning that the UK government has refused to specifically state whether she will be replaced with a similar platform after she leaves service in 2024. The loss of Argus without replacement in order to save money would, in the author's view, be a profoundly short-sighted decision. Considering how relatively cheap such a platform would be to purchase, convert and run, as well as the enduring utility of aviation platforms that can fill the sub-war fighting niche, the prudent choice would be to opt for a replacement with similar capabilities.

If RFA Argus has epitomised the enduring viability of the MAC concept for the RN in the twenty first century, then HMS Ocean has demonstrated that the fundamental guiding design principles of the WWII escort carrier still also hold relevance. Built for only £154mn in 1993 (£280mn in 2016) her construction costs were about the same as a Type 23 frigate, or less than a tenth the cost of a Queen Elizabeth class strike carrier. In order to achieve the low-cost she was built to reduced part-commercial standards and sacrificed other in other areas compared to a "full fat" fleet unit. She is limited by her inability to achieve high sprint and cruise speeds, has a relatively minimal self-defence armament and a noticeably shorter lifespan than ships built to full military standards. In exchange for these trade-offs the UK received a capital-size ship at a very low cost that was rapidly built and commissioned in four years.

While originally conceived of and built as a Landing Platform Helicopter (LPH) to support Royal Marine amphibious operations she, like Argus, has proved useful for a wide variety of rotary-wing aviation tasks. From her support of the UK intervention in Sierra Leone in 2000 and the RM invasion of the Al Faw peninsula during the 2003 Iraq War in her intended LPH role to acting as a makeshift "strike carrier" with Army Apache helicopters embarked during the 2011 Libya intervention. Since 2010 she has repeatedly led the UK high-readiness Response Force Task Group on its annual "COUGAR" deployment and acted as an auxiliary heliport, moored at Greenwich, during the 2012 London Olympics. As of June 2015 she is currently serving as the RN's flagship. It is expected that she will decommission in 2018, nominally replaced in the LPH role by HMS Prince of Wales.

HMS Ocean in the light strike role, with Army WAH-64 Apache attack helicopters

Ocean, like Argus, the Second World War MAC and the escort carrier continues to demonstrate that "second rate" aviation ships are not only a viable concept, but continue to fill essential niches that large strike carriers do not sit comfortably in. Ultimately the use of a 70,000 ton supercarrier to conduct HADR operations with its aviation assets will, in most circumstances, be a waste of one of the RN's most potent war-fighting assets. Similarly, placing a Queen Elizabeth class close enough to shore to act in the LPH role places an extremely high value asset at heightened risk of attack. In both circumstances a simple and cheap aviation platform is a far more appealing prospect, leaving the "proper" carriers available to deploy at short notice to do what they're best at: deterring and defeating serious threats to national interests.

Over the last two decades Ocean and Argus have acted as an effective adjunct to the UK's front line carrier fleet, made up of two Invincible class light ASW/strike carriers for most of these ships lives, they have performed essential auxiliary and supporting roles that freed up the fixed-wing carriers for other, more important, duties. It is a great shame that Ocean will not be replaced with another cheap LPH, she has added great value to the Royal Navy over her relatively short life. However, there remains hope Argus may yet be replaced with a similar auxiliary aviation platform. Failure to do so would almost certainly heap additional burdens onto the strike carriers and waste some of their awesome capability. Just like our predecessors concluded during the Second World War, if we are to make the most of our fleet carriers we need to invest in the auxiliary aviation platforms necessary to support them, allowing them to go where they need to be; rather than tied up with duties for which they are poorly suited.

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