"In the conventional aircraft approach the aircraft receives clearance from Air Traffic Control to descent from the bottom level of the holding stack to a given altitude where it would fly level until intercepting the 3 degree glidepath to the runway. In this flight level segment the aircraft requires additional engine power to maintain constant speed, resulting in an increase of fuel consumption and noise.A new approach procedure called Continuous Descent Approach (CDA) has been developed and is becoming widespread. In CDA procedures the aircraft stays higher for longer and then descends continuously, avoiding level segments, to the intercept point of the 3 degree glidepath. The CDA approaches reduce fuel consumption, CO2 and NOx emissions as well as noise levels.To take full advantage of CDA approaches, the continuous descent paths can be optimized to decrease even more the fuel consumption and noise and pollutant emissions. This proposal addresses an onboard fast optimiser for continuous descent approaches which calculates descent profiles minimizing the use of engine thrust and speed brakes while meeting ATC time requirements and maintaining airport landing capacity.To ensure a successful development of the fast optimiser, the Fastop proposal has been written by a consortium with remarkable parties skills that cover all the mathematical, programming and management needs required by the topic."