Airservices Australia, Boeing, the Air Traffic Alliance and Qantas are moving into the second phase of their tailored arrival procedures (TAP) project following successful completion of the first phase of the datalink trial at Australia's Melbourne and Sydney airports.

The first phase of the trial was launched in April and involved Qantas Airbus A330-200s and Boeing 747-400s using electronic arrival clearance instructions, instead of voice communications, on arrivals into the airports. Instructions were delivered by datalink from the beginning of descent to landing, with the controller-pilot datalink communication (CPDLC) route clearance message sent to the aircraft replicating the normal arrival procedure. While uplinking route clearance messages to datalink-equipped aircraft is already operational, to date this has been done in the cruise phase of flight, rather than descent and approach. Use for the approach promises fuel savings, reduced emissions, reduced noise and increased safety.

The flying component of the project was completed in September and since then the partners have been evaluating the results, says Craig Roberts, Airservices Australia's manager for the project. Four flights a week were conducted, with 70 to 80 trial flights completed in total.

Phase one was a success, says Roberts. "We proved that a ground system could uplink an arrival clearance that contained calculated speed and altitude constraints on the descent path, and that the clearance could be loaded into the aircraft's flight management computer [FMC] and flown to the ground," he says. "As the functionality does not yet exist on the ground to accurately calculate the required trajectories for the aircraft to fly as per the project scope, we didn't actually tailor any arrivals during phase one, although we did uplink the FMC's speed and altitude predictions for crossing certain waypoints on descent and sent those predictions back with the clearance as hard constraints for the aircraft to meet."

Based on initial calculations, Qantas estimates that it could achieve fuel savings of up to 120kg (265lb) per arrival for a Boeing 737-size aircraft and between 150kg and 210kg for a 747 using the new procedure. In the second phase of the project - over 18 months to two years from early 2005 - Roberts says a standalone prototype of a ground-based tailored arrivals system will be developed and tested on Airbus and Boeing simulators.


Source: Flight International