Development of a Unified Method to Predict Tendencies for Pilot-in-the-Loop Oscillations

There is a need for a unified method specifically designed to predict tendencies for pilot-in-the-loop oscillations (PIOs). The requirement for such a method is apparent from the significant number of castastropic PIOs that have occurred recently in modern fly-by-wire aircraft, such as the YF-22 and the Swedish Saab Gripen. To be successful, the PIO prediction method must: be accepted as valid by the manufacturers and government flight test organizations; account for all of the factors that contribute to PIO; be in a form that can be used for design guidance; and be easily calculated from flight test data. In the proposed Phase I effort, a candidate set of unified PIO criteria will be assembled following a thorough review of PIOs and their contributing factors and establishment of a database for criteria evaluations. A series of one-on-one information-gathering meetings is proposed with key members of industry and government to identify the consensus of opinion concerning PIO causes and the status of prediction criteria. There will be special emphasis on inclusion of all of the diverse ideas on methods to predict and prevent PIOs.