An ideal approach

NASA claims it is saving jet fuel by helping aircraft achieve the ideal glide path as they approach a crowded airport for landing.

NASA Ames Research Center and Boeing, in partnership with the US Federal Aviation Administration (FAA), United Airlines and the San Francisco International Airport (SFO), have completed trials to study the effectiveness of the Oceanic Tailored Arrivals (OTA) concept for aircraft landing at SFO.

Currently, the ideal landing approach, an even continuous descent, is often interrupted with course changes and altitude level-offs.

These deviations can result in increased fuel use, noise and environmental emissions. The study is investigating the customisation of aircraft descent procedures using the latest in communications and aircraft navigation technology and NASA air traffic management algorithms to maintain the ideal approach.

‘The goal of the Oceanic Tailored Arrivals initiative is to allow aircraft to descend in a manner that is fuel efficient and environmentally friendly,’ said Rich Coppenbarger, lead investigator for the Oceanic Tailored Arrivals Initiative at NASA Ames. ‘We are prototyping automation tools and procedures to help controllers strategically anticipate and solve arrival problems well in advance, allowing for more ideal descent operations, especially during busy traffic periods where potential benefits are greatest.’

During the initial portion of the trials, researchers are working with controllers at the FAA's Oakland Air-Route Traffic Control Center and the Northern California Terminal Radar Approach Control to tailor the approach of a United Airlines Boeing 777 equipped with advanced avionics, approaching SFO en route from Hawaii.

At approximately 300 miles from the destination airport, a four-dimensional descent profile, customised for each aircraft and airspace conditions, is generated with help from the NASA Ames-developed En Route Descent Advisor (EDA). The ideal descent profile is then transmitted via high-speed data link to the aircraft. Once reviewed by the flight crew, the profile is loaded automatically into the aircraft's Flight Management System (FMS) where it is used to compute a complete trajectory prediction to the runway. The FMS uses this prediction to accurately guide and control the aircraft to landing with very few manual inputs required by the flight crew.

Along with fuel savings, OTA approaches have the potential to significantly reduce noise and environmental impact at surrounding airports. Tailored Arrivals also may reduce workload by providing pilots and controllers with a common understanding of the intended arrival path and reducing the need for voice communications.

Tailored Arrivals enable pilots to fly airplanes as they were designed to be flown, which helps reduce crew workload and errors, according to Rob Mead, Boeing Phantom Works lead engineer for advanced air traffic management air/ground communications.

In addition to the SFO trials, Boeing has spearheaded trials in Australia and the Netherlands.

‘Early reaction from pilots and controllers to the OTA concept has been very encouraging,’ said Coppenbarger. ‘Initial fuel savings for a Boeing 777 have been estimated at 200 to 800 pounds per flight, in comparison with simulated operations representing congested traffic periods where continuous descent approaches are impeded,’ he added.

Trials are expected to continue later this year after the initial data are compiled and analysed.