Compass Issues 
Variation 
Deviation 
Magnetic Dip 
Oscillation 
Northerly Turning Error 
Cold/Hot Story 
(UNOS) Undershoot North, Overshoot South 
Acceleration/Deceleration 
(ANDS) Accelerate North, Decelerate South 
Paper Cup 
Lead and Lag in the A.I. 
Step on the ball 
Calibrated Leak on the VSI 
PFD and backup instruments 
MEMS/AHRS vs. Gyros vs. Magnetic Fields 
Flight Instruments MUST be working to survive spatial disorientation 
T.C. has dampening, over and under dampening can be fatal. 
PFD in general aviation aircraft are susceptible to pitot-static failures.