What with all the North Korea excitement, I thought it might be time to check on what the US Navy’s aircraft carriers are up to. This is always a useful way to distinguish “loud media yelling” from “something that might actually happen”. This information is helpfully collated here, but is in no way secret. To appreciate it, it’s worth understanding that the carriers have a very well-defined operating cycle that is linked with all kinds of other industrial and career processes.
Roughly speaking, a carrier is expected to deploy for six months out of every 24 months. Out of that six months, a bit less than a month is spent on passage between the home port and the area of operations. To avoid a gap, this means that the relief has to sail a month ahead of time. About every five years, the ship undergoes a really massive three-year overhaul, known as a RCOH for Refuelling and Complex Overhaul, during which the nuclear reactor is shut down, maintained, and refuelled. Half-way between RCOHs there’s another, six-month drydocking.
This establishes a cycle of readiness states – the ship comes out of dockyard hands, completes sea trials, works up through various levels of training, receives and re-qualifies its air wing, trains as a unit with the air wing (called a COMPTUEX), trains as a unit with the wider task force (called a JTFEX), and finally deploys. Having come back, the ship is available as a reserve for a while before the inexorable timetable demands that major maintenance begins and renders her immobile.
It’s possible to put maintenance off, but this is borrowing from the future – one of the reasons why carrier availability was very low at the time of the 2006-2007 war scares was the massive surge deployment at the end of 2001 and its partial continuation through 2003. It’s also possible to bring it forward, but this is very, very expensive (the RCOH is itself a multi-billion dollar project. The price of admiralty is high) and is subject to critical path restrictions. If, for example, one ship is on the slipway, obviously you can’t put another ship there. More subtly, the short-supply tradespeople employed on one ship can’t get to the next one until they’re done, and expanding the workforce is a long-term project.
On the other side of the book, the USN tries to maintain three major requirements – a carrier in the Middle East, another in the Western Pacific, and a third in Japan, which is permanently based there. As there are ten carriers, this should be possible within a classic one-out-of-three rotation, but it’s quite a bit more complicated than that because of the possibility that the major maintenance periods may fall at the same time.
So what’s up at the moment? Stennis, Truman, Reagan, and Lincoln – i.e. 40% of the force – are all in deep maintenance periods of one kind or another. It’s important to note that Reagan is the carrier based in Japan and is therefore logically the first to respond to any crisis in North-Eastern Asia. Her maintenance phase, or Selective Restricted Availability, was planned for four months from the 10th of January, so the fact she’s still tied to the pier may mean the work is dragging on, or more problems have been discovered during the work. Bush is deployed in the Persian Gulf, with a good three months of her deployment left to run.
Vinson, the one everyone is excited about, has been operating all year in the Western Pacific. Like Bush, she is mid-deployment and due to head for home towards the end of June. She recently headed back to the Western Pacific from a port call in Singapore.
Of the rest, Nimitz is working up the readiness cycle. She recently completed the COMPTUEX, which took the best part of a month. On this basis, assuming no sudden hurry, she is probably going to relieve either Bush or Vinson in June, sailing at the end of May. Roosevelt looks likely to be the next out, as Washington doesn’t have an assigned air wing. Eisenhower is the most recently returned, but that wasn’t very recent, as she arrived in Norfolk on the 30th December. She was at sea during February and March on occasion, providing training for reserve air crew, but as she has been back at the pier since the 24th of March I would think it’s getting time for some leave and some maintenance.
To sum up: out of the three routine tasks for carriers, one is covered by Bush while Vinson is doubling up on two of them. Overall availability is not unusually low, but it is not high either, as there is one carrier immediately available as a reserve while two reliefs will be needed for sailing dates in May. Vinson‘s recall to the Western Pacific may be more of an indicator that Reagan‘s return to availability is delayed than anything else.
Obviously, even one CVN is serious business. But just as in 2006-2007, there is no evidence of a mobilisation to match the talk.