Steeper landings set to cut aircraft noise

Aviation authorities and carrier Air Berlin are testing a new system of steeper landings and curved flight patterns to avoid residential areas in a bid to reduce ground noise by up to 40 percent, allowing more flights to land at night.

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The new approach, which experts say is just as safe as the technique now used, could make a big difference at congested airports such as Frankfurt, according to experts from the German Aerospace Centre (DLR), which announced the tests this week.

The DLR carried out 13 test flights at the Braunschweig research airstrip using a Boeing 737-700 aeroplane provided by Air Berlin.

“With the help of satellite navigation we can fly around residential areas during landing,” DLR director Dirk Kügler said in Braunschweig.

One flight tested the path that Frankfurt Airport – Germany’s busiest by far – hopes to begin using soon for night flights to avoid disturbing nearby residents. Noise measurements on the ground were taken for the test flight and will be analysed over coming months.

Ralph Riedle, head of aviation navigation firm Deutsche Flugsicherung, said the new, curved landing method was just as safe as the hitherto-used direct approach. He believed that the Federal Transport Ministry would approve the new technique this year and that it would start to be used at Frankfurt.

There, flights would swing around heavily populated areas such as Offenbach. DLR chairman Johann-Dietrich Wörner said that between the curved flights, the steeper landings and other measures, overall noise affecting residents should be reduced by about 40 percent.

“The communities in large areas around Frankfurt Airport are affected by noise from approaching aircraft,” Wörner said.

People in rural and sparsely populated areas may not be happier about the new approach: given the difficulty of finding unpopulated paths to fly over, the areas with fewer people will bear the brunt of the flight noise.

In an effort to cut noise altogether along the early section of the landing path, the test pilots started their descents later. Normally, a large passenger plane descends at a 3-degree angle, said Kügler, but this was increased for some test flights to 3.2 degrees, which was perfectly possible with modern commercial airliners.

The DLR is assessing the data on the steeper landings, particularly the effects on the plane and its crew, and any environmental impact.

The test landings used a cutting-edge GPS system called the Ground Based Augmentation System (GBAS) that pinpoints the position of the plane to within less than a metre. The precision means the pilot does not have to set a straight-line course as early in the flight as would normally be the case, but could rather manouevre the plane until a later stage.

Air Berlin boss Christoph Debus said the new GBAS was, at present, used only at Germany’s Bremen airport and Spain’s Malaga airport.

“It would be welcome if it were introduced at all airports,” he said.

First and foremost, it should be introduced at Düsseldorf, Nürnberg and the new Berlin-Brandenburg airport now being built, he added.

The Local/DAPD/dw