I can't see that the standby compass can be checked properly during taxi, as acceleration and lag errors are occurring all the time. The only reliable check for a standby compass, is to have the a/c stationary and a long way from any man made electromagnetic interference, for eg., lined up on a runway.
The standby compass needs to be checked for accuracy. Having said that it has to be the simplest therefore the most reliable instrument in the a/c provided it is swung correctly and is "floating", no air bubbles visible and no close interference.
Last edited by joehunt; 15th Dec 2007 at 04:46.