Landing Approach and Turn Studies

There is a large class of advanced flying qualities studies that has benefitted from modern pilot-in-the-loop technology without requiring delay-lead-lag mathematical models for the pilot. For loop closures made at frequencies of 1.0 radian per second or lower, simple gain models for the pilot appear adequate. Low-frequency closed loops characterize airspeed and path control outer loops.

STOL (short takeoff and landing) flight path control loops are the outer loops around higher frequency pitch attitude inner loops. The path loops can be closed with simple pilot

gains, assuming tight control of the inner loop (Ashkenas, 1988). Where some modest pilot lead is required to achieve the ideal integrator-type pilot-airplane transfer function in the crossover region, pilot ratings will be degraded.

Wings-level turn and turn coordination studies fall into the same category of low – frequency closed loops for which simple gain pilot models are adequate. The Ashkenas – Durand reversal parameter and the Heffley closed-loop studies of the naval carrier approach problem (Chapter 12) are yet additional examples of the use of simple pilot gain models.