Method for optimum economy cruise speed in an aircraft

An aircraft, comprising:

• an engine, configured to generate thrust for the aircraft;
• a guidance and control system configured to control a speed of the aircraft by controlling the thrust generated by the engine;
• and
• a flight management system comprising a computer programmed to execute the operations of:
• receiving a plurality of flight parameters including at least a weight of the aircraft, an aircraft bearing, an atmospheric pressure, an atmospheric temperature, a wind speed, and a wind bearing at the altitude of the aircraft;
• calculating a cost index coefficient associated with the flight of the aircraft, the cost index coefficient based on at least a cost index, the atmospheric pressure, and the atmospheric temperature;
• calculating a weight coefficient of the aircraft based on at least a weight of the aircraft and the atmospheric pressure at the altitude of the aircraft;
• calculating a wind Mach number;
• calculating an absolute value of a difference between the wind bearing and the aircraft bearing;
• and
• calculating an optimum Mach number of the aircraft, which provides the optimum maximum range cruise speed, wherein the calculation of the optimum Mach number comprises the weight coefficient, the cost index coefficient, the wind Mach number, and the absolute value of the difference between the wind bearing and the aircraft bearing;
• wherein the guidance and control system is further configured to adapt the speed of the aircraft to the optimum maximum range cruise speed.

A flight management system of an aircraft, comprising a computer programmed to execute the operations of:

• receiving a plurality of flight parameters including at least a weight of the aircraft, an aircraft bearing, an atmospheric pressure, an atmospheric temperature, a wind speed, and a wind bearing at the altitude of the aircraft;
• calculating a cost index coefficient associated with the flight of the aircraft, the cost index coefficient based on at least a cost index, the atmospheric pressure, and the atmospheric temperature;
• calculating a weight coefficient of the aircraft based on at least a weight of the aircraft and the atmospheric pressure at the altitude of the aircraft;
• calculating a wind Mach number;
• calculating an absolute value of a difference between the wind bearing and the aircraft bearing;
• and
• calculating an optimum Mach number of the aircraft, which provides the optimum maximum range cruise speed, wherein the calculation of the optimum Mach number comprises the weight coefficient, the cost index coefficient, the wind Mach number, and the absolute value of the difference between the wind bearing and the aircraft bearing.