A system for the real-time optimization of aircraft fuel economy, comprising: a data bus, one or more first sensors (101, 102, 103) for monitoring in-flight performance parameters, the one or more first sensors being coupled to the data bus; a flight deck display; and a processor coupled to the data bus and configured to receive information including in-flight performance parameters from the one or more first sensors, wherein the in-flight performance parameters comprise at least one of flight position, pressure altitude, Mach number, normal acceleration, temperature, engine state, fuel flow rate, engine bleed, power extraction, control surface and external configuration, gross weight, and to: calculate a current level of fuel-efficiency based on the received information, the current level of fuel efficiency being determined by comparing a flight model based on the received information with a predetermined expected performance level, the predetermined expected performance level being based on a predetermined flight model which takes into account the ideal in-flight configuration and the current real-time flight status, determine a deviation of the calculated current level of fuel-efficiency from an expected level of fuel-efficiency, determine, based on an analysis of the flight model, any in-flight performance operating parameter changes for improving fuel efficiency, and cause the determined parameter changes to be displayed on the flight deck display. a data bus, one or more first sensors (101, 102, 103) for monitoring in-flight performance parameters, the one or more first sensors being coupled to the data bus; a flight deck display; and a processor coupled to the data bus and configured to receive information including in-flight performance parameters from the one or more first sensors, wherein the in-flight performance parameters comprise at least one of flight position, pressure altitude, Mach number, normal acceleration, temperature, engine state, fuel flow rate, engine bleed, power extraction, control surface and external configuration, gross weight, and to: calculate a current level of fuel-efficiency based on the received information, the current level of fuel efficiency being determined by comparing a flight model based on the received information with a predetermined expected performance level, the predetermined expected performance level being based on a predetermined flight model which takes into account the ideal in-flight configuration and the current real-time flight status, determine a deviation of the calculated current level of fuel-efficiency from an expected level of fuel-efficiency, determine, based on an analysis of the flight model, any in-flight performance operating parameter changes for improving fuel efficiency, and cause the determined parameter changes to be displayed on the flight deck display. calculate a current level of fuel-efficiency based on the received information, the current level of fuel efficiency being determined by comparing a flight model based on the received information with a predetermined expected performance level, the predetermined expected performance level being based on a predetermined flight model which takes into account the ideal in-flight configuration and the current real-time flight status, determine a deviation of the calculated current level of fuel-efficiency from an expected level of fuel-efficiency, determine, based on an analysis of the flight model, any in-flight performance operating parameter changes for improving fuel efficiency, and cause the determined parameter changes to be displayed on the flight deck display.