Originally Posted by
Capn Bloggs
Of course they do (or at least, here they do). We have an approved MEL for our operation. Either operation for three days with the TCAS inop is in the MEL and therefore approved, or it's not. You can't have some wally in an out-office saying "the MEL doesn't apply, you have to have the TCAS working for every flight" because the base rule says you need it.
Not only that, but the base rule will say the equipment must be fitted to the aircraft, but there will be another rule allowing the development of an MEL that permits the fitted equipment to be unserviceable for a period of time. I haven’t checked FAR 121 but 135 is done that way and I’m sure 121 will have a similar clause.