Paris Air Show

GE’s FMS optimizes approaches

 - June 16, 2009, 7:11 AM

GE Aviation is here in Hall 2A Stand C137 exhibiting a flight deck with a flight management system (FMS) able to optimize approaches for reduced fuel burn and maximized runway usage, with time-of-arrival precision within a claimed seven seconds. In GE’s simulated flight into Frankfurt airport, the new FMS has the aircraft shaving 26 minutes off the average trajectory. Southwest Airlines has ordered the FMS for retrofit on its Boeing 737 Classics.

GE has called the concept four-dimension (three dimensions plus time) trajectory-based operations (4D TBO). Such continuous descent approaches have helped Scandinavian Airlines, which used the concept in 2008, flying 4,000 approaches at Stockholm airport. As a result it saved 240 metric tons of fuel, which translated into 756 metric tons of carbon dioxide not emitted. Nitrous oxide emissions were cut by 2.6 tons and noise reduction was significant, at 65 dB for the exposed area, according to GE.

The FMS builds the trajectory around the target time of arrival. It complies with a required navigation performance (RNP) of 0.1 nautical miles. “The aircraft flies within a narrow tube of 0.1 miles in radius,” Frédéric Daubas, GE’s chief marketing officer for aviation systems, explained to AIN.

In turn, this allows air traffic controllers to request aircraft trajectories sooner, so they can ensure separation between two aircraft at a fix, asking flight X to be there at a given time and flight Y two minutes later. They know separation will be kept until landing.

With normal procedures, controllers ensure separation at later stages, which requires them to employ more safety margins to ensure minimum separation is maintained and results in more segmented, longer approaches. Hence lower runway usage. This makes a difference when capacity is tight at busy airports like Frankfurt.

From the crew’s standpoint, tailored RNP makes the approach smoother. If the pilot has to reduce speed or accelerate, he does so earlier in the descent, Daubas said. Hence, lower noise on the ground and lower fuel burn. The latter is the translation of fewer speed changes.

Such approaches require just brief training for the crew, Daubas stressed. Also needed is some ground equipment. Finally, to see the flight path, the crew needs proper displays. Southwest’s retrofit will include replacing the old instrument panel with three 15-inch displays.