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Meeting	ACGS Committee Meeting 94 - Reno - November 2004
Agenda Location	9 SUBCOMMITTEE D – Dynamics, Computations and Analysis 9.1 Loss of Control Inhibitor System (LOCIS)
Title	Loss of Control Inhibitor System (LOCIS)
Presenter	Ralph A’Harrah
Affiliation	NASA Headquarters
Available Downloads*	presentation
	Downloads are available to members who are logged in and either Active* or attended this meeting.
Abstract	Current commercial aircraft exhibit uneven responses of the primary flight control surfaces to aggressive pilot control commands, resulting in a marked deterioration in the pilot's ability to control his aircraft, at a minimum, and can cause catastrophic loss of control, and loss of the aircraft. For older aircraft having mechanical control systems, this loss of harmony between the pilot and the control surface response can be attributed to the system compliance (e.g., stretching of the control cables, flexing of the push rods, servo valve distortion,) causing dynamic distortion of the control system hysteresis. In contemporary aircraft having fly-by-wire control systems, the major contributor to this loss of harmony between the pilot and the control surface is attributed to the control system time delays (resulting from the combination such items as computer cycle time, control shaping, filtering, aliasing, servo valve distortion, actuator rate limiting) between the pilots commands and the resulting responses of the flight control surfaces. In addition, on fly-by-wire aircraft, there is no feedback though the controls to the pilot on the state of the control system, such as surface flutter, surface jam, position limiting, actuator rate limiting, and the control limiting imposed by the operational envelop limits. The subject innovation would maintain harmony between the pilot's commands and the control surface responses, while providing improved feedback to the pilot on the state of his control system.