TACAN was in use donkeys years before GPS,RNAV etc came along so why would the answer depend on them, vinrouge?
Assuming its not a rhetorical question and you really don't know, Beagle, and not having had the pleasure of flying the lovely VC10, the answer is "not much". TACANs can be fitted on a ship, a building or even a truck none of which have such a thing as a North ref switch, so why would it matter? And in inverse bearing mode (if anyone's attention span has lasted this long) the reference pulse is aligned with a given part of the aircraft structure rather than a compass point. In any case, if a fighter cant find a great big tanker without a TACAN today is it really worth wasting fuel on?
If anything your question highlights the fact that maybe this particular capability holiday doesn't threaten the realm too much!
Last edited by ShotOne; 24th Nov 2013 at 19:27.