Flight and ground testing for pilot-induced oscillations

Until recently, discovery of pilot-induced oscillations (PIOs) in developmental flight testing has been by accident, with little planning for pilot-in-the-loop testing. This paper reviews the conventional test process and presents arguments for a change in philosophy to include specific tests for PIO susceptibility. PIO testing should be separate from flying-qualities testing, with unique pilot rating methods. Shortcomings in the current PIO tendency rating scale are examined, and a more comprehensive scale is proposed. Finally, it is shown that pilots´ perceptions of PIO and flying qualities differ consistently between flight and ground simulation testing. Pilot ratings are not as harsh in the simulator, even when the actual event is much more severe than it was in flight. From this, several rules are proposed for the use of ground simulation to investigate PIO susceptibility in future designs