In the '80's,
Dubai Airwing's 707 and 727s were fitted with dual Litton INS, plus a cold spare on board.
I was once instructed (in flight) by the Swedish Captain, to go down stairs into the lower 41 and change a U/S INS with the spare unit.
My reaction was??????????!!!!!!!!!!!!.....but was told to get on with it.
By the time I returned to the Flight Deck the F/E had given the capt. a short lesson on how an INS functions.
The moral of the story is...........You can always tell a Swede...but you can tell him nothing!!
No, the replacement unit could not be aligned in flight.
Tony