As often as they are canceled or late for maintenance repairs they probably have time to check them out every month since they are already running those stellar on time records of between 20% and 40% How many does AS still have in service? Most sites still say 17 but it has said that for quite a long time. At this point there almost has to be less than that since supposedly they will all be gone by October...Also according to the AS site only 10 remain. They could probably do 10 without much noticable delay. Like I said they are hours late half the time anyhow lol