Brussels airport is preparing to introduce continuous-descent approaches into its standard procedure after trials indicated promising fuel savings from the technique.
Over the course of 10 months last year, five operators - Brussels Airlines, DHL, Jetair, Singapore Airlines Cargo and Thomas Cook Airlines - took part in a test of the operation.
Belgian airspace is complex, owing to it being a crossing point between major European hubs and shared by four military bases. "In this context it is not easy to conduct optimal landings," says Brussels airport's operator which, along with Brussels Airlines and air traffic service Belgocontrol, makes up the B3 consortium overseeing the project.
The initial phase of the testing, from September to December 2010, collected data on aircraft descent profiles to optimise air traffic-control procedures and maximise the number of continuous approaches.
Operational tests ran until 30 October last year. Owing to the density of the airspace, and the demands of co-ordination, the procedure can only be conducted 15-70km (8-38nm) from the runway. Typically the continuous descent was authorised at 11,500ft (3,500m).
"Because of the required standard separations between aircraft, the procedure could not be applied at all times," says the airport operator, and was limited to about 9% of all participating flights, a total of around 3,000 over the course of the tests.
But the results indicate that aircraft the size of an Airbus A320 would typically burn 50kg less fuel, a saving which doubles for long-haul types, as a result of the ability to avoid thrust changes associated with step-down procedures. The consortium describes the saving as being significant, even with the limited availability. It adds that analysis from the University of Leuven showed a 2-3dB noise reduction 15km from the airport. "Now that the test phase has been successfully completed, the next step is to incorporate this 'green' landing technique in the official procedures," says the consortium.