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FAST OPtimiser for continuous descent approaches

Final Report Summary - FASTOP (FAST OPtimiser for continuous descent approaches)

Executive Summary:
FASTOP is a research and development project funded by the Clean Sky Joint Technology Initiative (JTI). This framework was created by the European Commission for funding research projects in Europe with the contribution of private investment. Clean Sky aims at contributing to aviation emissions (CO2 - carbon dioxide and NOx - nitrous oxides) and perceived noise reduction targets set by the Advisory Council for Aeronautics Research in Europe (ACARE) for 2020.

FASTOP takes place inside the “Systems for Green Operations” (SGO) Integrated Technology Demonstrator (ITD) that is developing new mission and trajectory management systems

Conventional aircraft approaches involve step-wise descents that are flown sequentially as longs as the aircraft crew receives clearances from the Air Traffic Control to descent to a lower flight level. At the final approach point, the aircraft is typically aligned with the extended runway centreline and intercepts the 3 degree glide path of the ILS that guides it to the landing runway threshold. In all level segments of this kind of descents, the aircraft requires additional engine power to maintain a constant altitude (even if decelerating), resulting in an increase of fuel consumption and noise over populated areas in the vicinity of the airport.

A new approach procedure called Continuous Descent Approach (CDA) has been developed and is becoming widespread in many airports. In CDA procedures the aircraft stays higher for longer since the descent is performed continuously, avoiding level segments. Ideally, a CDA starts at the Top of Descent point at the last cruise altitude up to the point to intercept the ILS glide path. Thus, CDA approaches reduce fuel consumption, CO2 and NOx emissions as well as noise levels.

A major drawback of CDA operations is the reduction of airport and/or Terminal Manoeuvring Area (TMA) capacity, since vertical separation strategies between conflicting aircraft become more complex for the ATC. In order to partially overcome this issue, ATC may issue time requirements to aircraft to meet certain waypoints (such as in the TMA entry, initial approach fix, final approach fix, etc.).

FASTOP addresses an onboard fast optimiser for CDA that calculates descent profiles minimizing the use of engine thrust and speed brakes while meeting ATC time requirements. This optimisation process is launched each time the actual trajectory deviates from a certain error threshold from the intended one.

The project achieved to develop a near real time optimizer in C++ that uses the CONOPT non-linear programming solver. In few seconds, the optimizer is able to compute a new trajectory taking into account parameters like wind, real pressure, flight path angle dynamics, fuel flow, STARS approach and various types of aircraft models. The Optimizer was correctly integrated in the simulator of NLR in Amsterdam and flight test evaluations are foreseen in 2015.

Project Context and Objectives:
The present report summarizes all the Fastop activities carried out during the 15 months of the project from the 1st November 2012 to the 31st March 2014. An extension of 2 months was requested the 9th December 2013 and the agreement was formally accepted the 31st March 2014. The project lasts therefore 15 months instead of the 13 months initially planned.

The main objectives of the project were:
• Improve the TEMO CDA optimizer for TRL5 & flight test evaluation,
• Improve mathematical model including collocation benchmarking,
• Asses different NLP solvers (GAMS Benchmarking),
• Implementation of a FASTER solution,
• Evaluation in the NLR flight simulator.

Project Results:
GTD, UPC and ASCAMM will share the foreground of the developed library. The consortium signed the 13th November 2012 a statement of joint overnership with NLR. NLR is therefore the joint owners of all deliverables listed inside the Fastop Technical Annex I.
Potential Impact:
UPC wrote a white paper entitled “Enhancement of a time and energy management algorithm for continuous descent operations” and will present the FASTOP development in the AIAA conference planned for the 16th June in Atlanta. GTD will present the project and perform a demo in the Clean Sky SGO review that will take place in Toulouse the 3rd June 2014.

No Patent or commercial exploitation is at present time foreseen.
NLR will further evaluate the potential benefit of FASTOP in a flight test campaign planned for 2015. GTD. UPC and ASCAMM will follow their investigation in the trajectory optimization field.