Real-Time Trajectory Predictor Calibration through Extended Projected Profile Down-Link

This paper investigates the capability of the Extended Projected Profile (EPP) trajectory down-link definition to facilitate air-ground trajectory synchronisation. It will be demonstrated that the EPP allows for practically unambiguous description of aircraft intent, but that unknown aircraft performance characteristics such as climb thrust derate, anti-ice and tail-specific drag adjustments can still lead to significant errors. These errors especially impact the ‘what-if’ functionality of ground-based trajectory predictors essential to effective trajectory negotiation and management. A method is proposed that uses the EPP down-link trajectory to determine an aircraft performance calibration function accounting for any variables not specifically recorded in the EPP, thereby ensuring high accuracy for ‘what-if’ trajectories. Where EPP on its own synchronises the current trajectory, in combination with the calibration proposed in this paper, it can synchronise the ground trajectory prediction process with that of the FMS. EPP therefore enables the ground to properly synchronise with the aircraft and creates value based on airborne and ground-based trajectory prediction capabilities. Keywords; TBO; data-link, EPP; 4D-TRAD; trajectory synchronisation; AIDL.