One such initiative came together in 2008 when Airservices Australia , Airways Ne w Zealand and the US Federal Aviation Administration joined to create the Asia & South Pacific Initiative to Reduce Emissions (ASPIRE). The joint venture is designed to lessen the environmental impact of aviation across Asia and the South Pacific with each partner focusing on developing ideas that contribute to improved environmental standards andoperational procedures in aviation.

Since the group’s inception the ASPIRE membership has expanded with the inclusion of Japan Civil Aviation Bureau (JCAB) in October 2009 and the Civil Aviation Authority of Singapore (CAAS) in February 2010.

“When the various aviation service providers came together it was quite clear there are many opportunities to improve air traffic management and with the consequential improvements to operational efficiency which then flow on to environmental benefits,” said Civil Aviation Authority of Singapore (CAAS) director, Air Traffic Service, Ng Tee Chiou.

A key initiative of the group to date has been the use of Optimised Profile Descent (OPD), or so-called continuous descent, designed to reduce fuel consumption and noise compared with a conventional approach. The OPD involves maintaining a constant three degree descent angle during landing, until meeting the Instrument Landing System (ILS).

Basically, instead of approaching an airport in a stair-step fashion, throttling down and requesting permission to descend to each new (lower) altitude, OPD allows for a smooth, constant-angle descent to landing. This reduces noisepollution and saves fuel.

Demonstration flights
ASPIRE has undertaken a series of demonstration flights using OPD with carrier partners Air New Zealand, Qantas, United Airlines, Japan Airlines and Singapore Airlines.

“The demonstration flights demonstrated quite a lot,” says Ng. “They show that just today, leveraging the existing technology we have, there is so much potential.”

The CAAS has conducted trials with Singapore Airlines (SQ), from which it ascertained it can do about 30-36 per cent of incoming flights with OPD landings, Ng said.

In a 31 January multi-sector demonstration flight from Los Angeles-Tokyo- Singapore, SQ was able to show that the flight saved 10,686kg of fuel and cutcarbon emissions by 33,769kg compared to normal practice, as well as achievinga reduction in flight time of 33 minutes.

Aside from using OPD landings, the B747-400 aircraft also tapped other best practices including: An airframe wash and polish including engine wash, tailored water uplift, just in time fuel loading. The flight was also given priority clearance for taxiing and departure with unimpeded take-off without restrictions on speed or aircraft level.

User Preferred Route (UPR) and Dynamic Airborne Reroute Procedures (DARP) were also employed during the cruising phase to allow the pilot to capitalise on prevailing wind patterns to alter the aircraft’s flight path to shorten its flight time and achieve greater flight efficiency. In addition, Performance Based Navigation (PBN) procedures such as a reduction in the lateral and longitudinal flight separation were employed, allowing the aircraft to use preferred flight paths and levels.

While use of all of these procedures would certainly not be available on a widespread, everyday basis, they do visibly demonstrate the benefits available from even just making use of a portion of them.

Technology enabler
The OPD is a two way thing, as air traffic control (ATC) at Changi Airport can initiate it as and when the traffic situation allows it, or pilots can request it, “but of course if traffic is too complex during the peak hours then we’ll just say no,” he said.

Ng adds that more efficient use of the airspace, which he highlights is a finite space, will not only provide operational and environmental benefits, but will allow the entire system to absorb the growing utilisation of that finite space.

Modern avionics have enabled virtually all of the more efficient procedures including OPD and this says Ng, “is the beauty of ASPIRE because it leverages on existing technologies.”

“We hope that through these demonstration flights other air servies providers and airlines will see that the opportunities are there and implementing bits of it here and there will all add up and benefit the environment,” he said.

CAAS plans to trial the OPD with other airlines, many who have shown keen interest, Ng adds, as well as officially roll it out by year end.