I have been told that the RAF recruit 500 pilots a year
By whom? Be very wary of believing everything you hear...
It may be that the RAF invites 500 candidates a year to OASC, but they certainly don't take on 500 pilots a year! For a start, there wouldn't be enough slots at IOT for all of them - even if all IOT courses comprised all pilots and no other branches! - and secondly, taking 500 a year would increase pilot numbers to a level the RAF can only dream of...even with the current PVR rates, we're not losing 500 a year!