Under the plan, overnight flights will soar above the Northwest Side about every other week until Oct. 14. View Full Caption Shutterstock

CHICAGO — Overnight take-offs and landings at O'Hare Airport shifted onto a new schedule on Monday, as the third phase of the city's Fly Quiet Runway Rotation test goes into effect this week.

The test, aiming to spread the burden of overnight jet noise over a different swathe of neighborhoods or suburbs each week, has run continuously since its second round kicked off April 30.

But starting Monday, aviation officials gave air traffic controllers a new map to follow between 10 p.m. and 6 a.m., this time avoiding a diagonal runway that's set to be decommissioned in early 2018. The plan sends overnight flights over the city's Northwest Side during every second week, leaving city skies largely quiet the other half of the time.

New O'Hare 'Fly Quiet' Rotation Underway: See When Jet Noise Will Be Worst View Full Caption

A schedule showing runway rotations during the second round of the Fly Quiet test, which ran from April 30 to July 16 this year. [DNAinfo/Alex Nitkin]

The third round of the test, set to run from July to October, would switch out two rotation patterns to exclude a diagonal runway that's set to be decommissioned next year. [DNAinfo/Alex Nitkin]

The current round of the program runs for 12 weeks, expiring on Oct. 14. After that, air traffic controllers will revert back to the simpler, four-configuration Fly Quiet program established in 1997.

Last year, the O'Hare Noise Compatibility Commission approved the first runway rotation program in the face of widespread demands that the city temper the noise from low-flying planes. Between July and December, the program directed overnight flights to change their takeoff and landing paths every week, ideally keeping any one neighborhood from being pummeled for too long.

Earlier this year, the commission approved a 12-week follow-up program to run between April 30 and July 16. In June, the group voted to extend the program another three months, but without the diagonal runway.

After the program expires in October, aviation officials will draw up a new rotation schedule that can span the period between the diagonal runway's decommissioning in the spring and the introduction of a new east-west runway coming in late 2020, according to Aaron Frame, a deputy commissioner for the Chicago Department of Aviation. Federal law mandates that any rotation lasting longer than six months would have to emerge from an extensive "environmental impact study" of noise and flight patterns.

Frame said last month that testing a rotation that excludes the soon-to-be-closed runway would give researchers a better idea of how to craft the longer-term plan.

But members of the Fair Allocation in Runways coalition had argued that the extra runway should remain in the mix as long as possible, writing in a statement that removing it "places an unnecessary burden on these communities in the form of wide-bodied aircraft every night of the rotation."

About 100 flights take off and land at the airport between 11 p.m.-7 a.m. every night, when the rotation program will be in effect.

City residents filed almost 127,000 jet noise complaints with the city between July and December last year, while the rotation plan was in effect — about an 11 percent drop compared to the previous six months, according to data released by the commission. The number of people filing complaints, meanwhile, fell by about 15 percent.

During last year's test, pilots used their designated takeoff or landing path about half the time, officials said. Another 19 percent of flights followed a "secondary" path, offered so pilots can land safely against the wind during storms. All other times, pilots chose to forego both suggested patterns.

The below maps show both the primary and secondary runway patterns planned for each week of this year's rotation test.

This week, departing flights will swoop over neighborhoods all around the city's Northwest Side. A secondary pattern will send arriving flights along the same paths:

[Chicago Department of Aviation]

During the week of July 30, no flights will be directed over city neighborhoods. But during last year's test, rough weather led pilots to forego their suggested runways about 30 percent of the time, and they have the same option this year:

[Chicago Department of Aviation]

During the week of Aug. 6, departing flights will swoop over neighborhoods all around the city's Northwest Side. A secondary pattern will send arriving flights along the same paths:

[Chicago Department of Aviation]

During the week of Aug. 13, no flights will be directed over city neighborhoods. But during last year's test, rough weather led pilots to forego their suggested runways about 30 percent of the time, and they have the same option this year:

[Chicago Department of Aviation]

During the week of Aug. 20, arriving flights will swoop over neighborhoods all around the city's Northwest Side. A secondary pattern will send departing flights along the same paths:

[Chicago Department of Aviation]

During the week of Aug. 27, no flights will be directed over city neighborhoods. But during last year's test, rough weather led pilots to forego their suggested runways about 30 percent of the time, and they'll have the same option this year:

[Chicago Department of Aviation]

During the week of Sept. 3, arriving flights will swoop over neighborhoods all around the city's Northwest Side. A secondary pattern will send departing flights along the same paths:

[Chicago Department of Aviation]

During the week of Sept. 10, no flights will be directed over city neighborhoods. But during last year's test, rough weather led pilots to forego their suggested runways about 30 percent of the time, and they'll have the same option this year:

[Chicago Department of Aviation]

During the week of Sept. 17, departing flights will swoop over neighborhoods all around the city's Northwest Side. A secondary pattern will send arriving flights along the same paths:

[Chicago Department of Aviation]

During the week of Sept. 24, no flights will be directed over city neighborhoods. But during last year's test, rough weather led pilots to forego their suggested runways about 30 percent of the time, and they'll have the same option this year:

[Chicago Department of Aviation]

During the week of Oct. 1, departing flights will swoop over neighborhoods all around the city's Northwest Side. A secondary pattern will send arriving flights along the same paths:

[Chicago Department of Aviation]

During the week of Oct. 8, no flights will be directed over city neighborhoods. But during last year's test, rough weather led pilots to forego their suggested runways about 30 percent of the time, and they'll have the same option this year:

[Chicago Department of Aviation]