f all the tasks in the RAF and RN, ASW is the one that requires the most training, crew co-ordination and current practice
I suspect it is, actually, not least because it requires people to find extremely quiet things under the water where most non-acoustic sensors can't reach. This isn't intended to minimise the other roles required of sea and airborne units, but ASW is very difficult indeed to do properly, and the difference between good enough* and not good enough is paper thin.
Dave
*apologies to Boggy if he's reading this, I didn't mean him <g>