CHICAGO (CBS) — The FAA has approved a new overnight runway rotation at O’Hare International Airport, as officials try to find the best way to evenly distribute jet noise at night.

For 12 weeks, starting the night of April 30 and ending the morning of July 23, the Chicago Department of Aviation will try various runway configurations, alternating between parallel and diagonal runways.

It’s the second overnight runway rotation tested by the city, with a third planned for later in the year.

Half of the 10 runway configurations to be used in this round of tests will be different than those used in the first rotation.

Aviation Department Commissioner Ginger Evans said the new rotation aims to improve on the first one by taking into account feedback from the FAA, airline pilots, and the O’Hare Noise Compatibility Commission.

After all three rotations have been tested, the city will determine the best configuration for evenly spreading nighttime noise, and that Fly Quiet program will be used on a long-term basis, from next year until a new parallel runway opens in 2020.

For more information on the Fly Quiet tests at O’Hare, click here.

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