Pilot-Induced Oscillations


From the Wright Flyer to fly-by-wire, the phenomenon of pilot-induced oscillations (PIO) has been observed on prototype, experimental, and operational military and commercial aircraft. Throughout our history, Systems Technology has led the industry in comprehension, analysis, and prevention of this troubling phenomenon. Work began in the early 1960’s with high profile PIO events involving the T-38, F-4 Sageburner, and X-15.

Activity peaked again in the mid 1970’s with the Shuttle ALT-5 and F-16 Flight Zero events and in the early 1990’s with several severe events that were characterized by actuator rate limiting associated with flight control systems including the YF-22 and SAAB Gripen. Each generation featured advancement in prediction and analysis methods. Specific Systems Technology activities have included the analysis of PIO susceptibility for a wide range of military and commercial transport aircraft, the development of PIO-specific criteria and analysis techniques including nonlinear system methods, and the definition of flight test methods. Recent work has focused on PIO alleviation concepts including Smart-Cue/Smart-Gain and SAFE-Cue.

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