Automatic flight control systems and methods

An aircraft flight control system for use with a primary flight display (PFD), the system comprising:

• on-board sensors for providing sensor data comprising environmental data and sensed engine thrust data;
• a navigation system for providing inertial data comprising a flight path angle, attitude, and airspeed;
• a control module comprising a processor and a memory, the control module configured to:
• receive the sensor data;
• receive the inertial data;
• receive a target airspeed;
• process the inertial data, the sensor data, and the target airspeed, to determine (i) a maximum potential flight path (max PPFP), defined by a maximum thrust at the target airspeed, and an idle PPFP, defined by an idle thrust at the target airspeed;
• and
• generate display commands for symbolic indicators of (i) the flight path angle, (ii) the max PPFP and (iii) the idle PPFP;
• determine that the aircraft is in a speed controlled zone when the max PPFP is greater than the FPA, and the FPA is greater than the idle PPFP;
• and
• command the PFD to display an indicator of an auto-throttle (A/T) mode in a first designated area, and a status annunciation in a second designated area, when the aircraft is in the speed controlled zone;
• and
• a primary flight display (PFD) coupled to the control module and configured to receive the display commands and render symbology and indicators responsive thereto.

A method for an aircraft flight control system for use with a primary flight display (PFD), the method comprising:

• at a control module,
• receiving sensor data comprising environmental data and sensed engine thrust data, from on board sensors;
• receiving navigation data comprising a flight path angle, attitude, and airspeed, from a navigation system;
• receiving a target airspeed;
• processing the navigation data, the sensor data, and the target airspeed, to determine (i) a maximum predicted potential flight path (max PPFP), defined by a maximum thrust at the target airspeed, (ii) an idle PPFP, defined by an idle thrust at the target airspeed;
• generating display commands for rendering (i) the flight path angle, (ii) the max PPFP and (iii) the idle PPFP;
• defining an Auto-Throttle (A/T) speed controlled zone in which the max PPFP is greater than the FPA, and the FPA is greater than the idle PPFP;
• determining when the aircraft is in the A/T speed controlled zone;
• commanding the PFD to display an indicator for speed in a first designated area and an indicator for cruise in a second designated area on the PFD when the aircraft is in the A/T speed controlled zone;
• and
• when the aircraft is not in the A/T speed control zone,
• determining (a) when the FPA is more than a configurable predetermined upper margin above the max PPFP;
• determining (b) when the FPA is more than a configurable predetermined lower margin below the max PPFP;
• in response to one of the conditions (a) and (b),
• determining a predicted speed (PS) associated with the FPA;
• and
• commanding the PFD to render a third symbol indicating the predicted speed (PS) on an airspeed indicator responsive thereto.
• and
• at the primary flight display (PFD),
• receiving the display commands and rendering indicators responsive thereto.