By Joseph E. (Jeb) Burnside

Instrument-rated pilots understand they cannot maintain control of their aircraft without referencing the gyroscopic flight instruments. These include, of course, the artificial horizon or attitude indicator and the directional gyro, which are usually air- or vacuum-driven, plus the turn coordinator or turn and bank indicator, usually powered by the aircraft’s electrical system.

But these instruments and their systems, being mechanical devices, can and do fail. The first indication usually is a disagreement between the artificial horizon and the turn coordinator: the former will begin to show a bank while the former won’t. The directional gyro soon will confirm the bank, leaving the pilot with two instruments showing…