WASHINGTON, DC DEC 20: A helicopter patrols the area around the U.S. Capitol as part of the regular security measures in place in Washington. (Michael S. Williamson/The Washington Post)

Washington-area residents have long complained about the impact of helicopter noise on their neighborhoods, but data about the flights, flight paths and which neighborhoods are most heavily impacted has been hard to come by.

That may now change. The Government Accountability Office at the request of lawmakers from the District, Maryland and Virginia, said it will study the issue starting this fall. The GAO did not say how long it would take to complete the study.

Lawmakers, including D.C. Del. Eleanor Holmes Norton (D), Maryland Reps. Jamie Raskin (D), Anthony G. Brown and David Trone (D) and Virginia Reps. Gerald E. Connolly (D) and Don Beyer (D) asked the GAO to examine the issue in January. The representatives said they have been getting a growing number of complaints from residents about the noise and its impact on their lives.

While residents recognize they live in a region that is home to numerous military and medical installations and that some impact is to be expected, lawmakers say they want to find a way to continue that work, but reduce the impact on the people who live here.

"As residents of the District and the region can attest, helicopter noise from police and military helicopters continue to plague many of our neighborhoods,” Norton said. “This study is an important step toward getting much-needed information to deliver relief to our communities and making sure we minimize disruptions to neighborhoods and families.”

When Beyer, whose district includes neighborhoods near the Pentagon, held a town hall on the issue last year, more than 200 people attended. He said he has tried to work with Pentagon officials on ways to reduce the noise, but has been disappointed with their response.

"The GAO study should, I hope, give us much better information with which to address this issue,” he said.

Brown, (D) whose district includes Prince George’s and Anne Arundel counties, said the issue is “top-of-mind” for many of his constituents.

“I am thankful it is being treated with the seriousness it deserves,” he said.

Unlike noise complaints tied to operations at the region’s three airports, Baltimore-Washington International, Dulles International and Reagan National airports, helicopter noise is difficult to track because it is not always easy to determine which agency operates a particular aircraft.

Among the issues lawmakers hope the GAO study will examine: the types of aircraft operating in the region and their noise levels; the frequency of flights; flight paths and the degree of coordination between agencies that operate the helicopters and whether pilot training could be modified to lessen the impact on residents — particularly at night.