Matthew Lloyd/Bloomberg

London Heathrow Will Test Steeper Plane Approaches to Trim Noise

London Heathrow airport will begin trialling steeper aircraft approaches next month in a push to reduce noise as it seeks to win support for the addition of a third runway.

Air traffic controllers at Europe’s busiest hub will begin guiding planes in at an approach angle of 3.2 degrees, compared with the standard 3 degrees, Heathrow said in a statement Monday. The six-month trial, due to begin on Sept. 14, does not require any special training or changes to equipment.

Prime Minister David Cameron has said he’ll decide by the end of the year whether to allow the expansion of Heathrow after a state-appointed commission identified the hub as the best option for a new runway serving southeast England. Opposition to the 18 billion-pound ($28 billion) plan, which would lift passenger numbers above 135 million by 2050, centers on the extra noise that an expanded airport would create.

“The steeper the angle, the less time an aircraft spends at low altitudes, which means that fewer people should be affected by higher levels of noise,” Heathrow said. Jets coming in to land at the steeper angle would be 170 feet higher on commencing final approach about 9 miles from touchdown, it said, with noise monitors helping to gauge changes in volume.

Those aircraft with the right gear will be invited to take part in the experiment, except in periods of poor visibility, with other planes sticking to the shallower glide-slope. Should the trials prove successful Heathrow could explore options for a 3.5 degree approach angle which would cut noise further.

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