"the Department to meet its operational requirement to have five ships at sea at any one time. This requirement remains unchanged despite the cut in numbers to six. The Department cannot commit to always maintaining this level of availability. It told the Committee that it will be able to maintain four ships at sea, and while there is very high probability of maintaining five, there is a small risk it will not."
Well that was wrong on all counts - that's the problem with any risk based analysis - small chances can still occur but if you have enough units it's not critical. It's when the outliers happen and you have no depth that you are stuffed