Arrivals Optimisation includes any one of several procedures available to aircraft operators and ANSPs to improve the fuel efficiency for aircraft during final descent phase of a flight. Arrivals Optimisation minimises fuel burn for the arrival segment by enabling each jet to fly the optimum track to Top of Descent (TOD) and an Optimised Profile Descent (OPD) from TOD to the landing runway.
Qualifying arrivals optimisation procedures include continuous descent arrivals, continuous descent approaches, optimised profile descents, tailored arrivals, and are generally referred to by ICAO as Continuous Descent Operations.
Optimised Profile Descents
An Optimised Profile Descent (OPD) is a cockpit-based flight technique where the vertical profile of an arrival is optimised to minimise undesired level flight segments so that the aircraft can be flown with engines at idle thrust from a high altitude, potentially from cruise, until touch down on the runway. Aircraft executing an OPD realise a far more efficient fuel burn profile and reduced emissions during the descent and arrival phases of flight, as compared to a traditional arrival path. A variety of OPD applications have been analysed and developed for fuel and emission efficiency improvements.
OPD via RNAV and RNP-AR Approaches
Under certain conditions the airspace restrictions, arrival, departure and en route traffic flows can be modified to, enable optimal arrival descent profiles on published Area Navigation (RNAV) and Required Navigation Performance – Authorisation Required (RNP-AR). This optimisation reduces fuel burn and carbon emissions by taking advantage of the sophisticated navigational capability of modern aircraft that can fly closer to optimal tracks and altitudes.
OPD via Tailored Arrivals
Another application of OPD procedures, known as a Tailored Arrival (TA), is a procedure where trajectories are dynamically optimised for each aircraft to permit a fuel-efficient, low-noise descent profile that has imbedded compliance with arrival sequencing requirements and other airspace constraints.
Operational trials in Australia, New Zealand, and the United States have demonstrated that both types of OPD described above provide significant fuel and emissions savings. Although the successful execution of an uninterrupted OPD is greater during periods of light traffic, the ASPIRE partners are pursuing the use of OPD during congested traffic periods under the ASPIRE Work Programme (See Section 7).