Identifying a Pilot-Induced Oscillation Signature: New Techniques Applied to Old Problems

Elimination of pilot-induced oscillations by design remains an elusive goal. Throughout the history of powered flight, as manual flight control systems have morphed and evolved, so too have the pilot-induced oscillations that often plague them. In the mid-1990s, the United States Air Force declared as part of its Unified Pilot-Induced Oscillation Theory program that the cumulative reduction of pilot-induced oscillations shall be 80% via criteria, 99% via evaluation methods, and 99.95% via detection and compensation. This too remains an elusive goal. One reason lies in the lack of consensus regarding the definition of exactly what is a pilot-induced oscillation. The intent of this paper is to coalesce the many definitions of pilot-induced oscillation into a single entity. Then, newly developed analysis techniques are applied to a flight-test database to expose the unique characteristics or signature of pilot-induced oscillations, at least as they apply to a representative mission operation: the probe-and-drogue aerial refueling task.