Abstract: In an automatic flight control system of the type having automatic stabilizer trim control, the long term, constant altitude cruise trim threshold limits which alter the maximum and minimum pull-in/drop-out deflection of the elevator relative to the stabilizer minimize the steady-state downward deflection of the elevator, thereby reducing unnecessary aerodynamic drag and realizing significant savings in fuel costs.

Abstract: The flight path transition control apparatus provides a roll attitude command to control the aircraft to execute an exponential transition path to a predetermined course in accordance with the exponential control law Y+KY where Y is the lateral displacement of the aircraft from the predetermined course, Y is the rate of change of the lateral displacement and K is a time constant of the system. A predictive roll command .phi..sub.p is generated in accordance with ##EQU1## where V.sub.g is the aircraft ground speed,TAE is the track angle error of the aircraft with respect to the predetermined course,TAE.sub.0 is the track angle error of the aircraft with respect to the predetermined course at capture maneuver initiation,g is the gravitational constant, andt is the elapsed time following capture initiation.The predictive roll command .phi..sub.p is combined with the exponential control law to provide the aircraft roll attitude command .phi..sub.c =.phi..sub.

Abstract: Control apparatus for an aircraft area navigation system computes a predetermined curved path from the inbound course to the outbound course of a waypoint or the inbound course to the next waypoint and provides aircraft steering signals with regard to the predetermined curved path. A bank angle bias command is applied to the apparatus for effecting transition from the inbound course to the curved path and is removed when the aircraft transitions from the curved path to the outbound course. Cross track and track angle error signals are generated with regard to the predetermined curved path for steering the aircraft thereon as the course transition is effected.