Rustle,
Some had a system failure mode eg static leak, blocked pitot, gyro failure or whatever. Others had individual verniers for each instrument so you could gradually wind in the changes.
Some were just on or off but even that beat the a/c because the student didn't get the visual warning from my hand applying the cover-ups.
At BAe in Oz we also used to do full & partial panel climbing/descending/turning exercises with the a/c on the back of the power curve. Quite good for developing scan & coordination. The tolerances were (I think) +/- 100', 100'/min, 5kts, 5 deg hdg for a minimum pass. A better pass if you halved those.
Last edited by Tinstaafl; 24th February 2003 at 20:04.