Propulsion control with flight director guidance as an emergency flight control system

The NASA Dryden Flight Research Center has developed a Propulsion Controlled Aircraft, or PCA, system in which computer-controlled engine thrust is used to provide emergency flight control capability. Using this system, F-15 and MD-II aircraft have been successfully landed without the use of primary flight controls. However aircraft, not equipped with full-authority digital engine control, require implementations of PCA technology that can be installed on existing systems. Piloted transport aircraft simulation studies at the NASA Ames Research Center have examined a "PCA Ultralite" concept, in which thrust control is provided through a combination of the autothrottle system and manual pilot control with the aid of flight director guidance. Existing autothrottle systems were found to provide adequate thrust-only pitch control for achieving a safe runway landing. However the level of difficulty of manual lateral-directional control was found to vary between aircraft. While certain flight director implementations were found to provide adequate guidance for some aircraft in regards to achieving successful runway alignment, alternate flight director implementations still need to be investigated to determine if satisfactory performance can be achieved on all PCA capable aircraft.