Mark

Without verification..... I believe the old style "Wet Compass" needs calibration once a year. This is not to say it must come off the aircraft and go to shop, but rather taking the aircraft out to a compass rose (which hardly any airports have any more) and checking the compass on 30 degree radials.

With a digital standby compass, I would say spinning the aircraft is not needed.

It really is a joke though..... if you're down to just the standby compass for navigation, your problems are much larger than just what heading you're on.

Each airline should state requirements needed in their GMM or General Maintenance Manual.