LONGMONT — Citizens for Quiet Skies announced Monday evening that it would sue Mile-Hi Skydiving, claiming the company’s planes present a noisy nuisance to residents in Longmont and Erie.

The Longmont-based group has clashed with the skydiving company for about two years, with the city of Longmont — which operates Vance Brand Municipal Airport — often caught in the middle. In that time, supporters and opponents of Mile-Hi have frequently argued over how much noise the company really generates or what anyone can do about it.

Quiet Skies spokeswoman Kimberly Gibbs said she hoped the suit would move things off of dead center.

“Limbo’s a terrible place to be,” she said. “We’re no longer in limbo.”

The group said it would file the lawsuit Tuesday. A formal announcement is scheduled for 6:30 p.m. in meeting room A of the Longmont Public Library, 409 Fourth Ave.

Mile-Hi owner Frank Casares could not be reached for comment.

The company has been operating at the airport since 1995 and has used its most recognized plane, a purple and white De Havilland Twin Otter, since 1999.

Noise complaints began to increase in 2009, though just how much could be hard to tell. In 2010, for example, the airport received 488 calls complaining about Mile-Hi; according to airport records, 332 of them came from three people.

The most recent public dispute came in August, when Mile-Hi stopped announcing its nighttime skydives. The company had been giving advance notice to Longmont officials — both to warn people who disliked the noise and to alert people who enjoyed watching — but said there no longer seemed to be a point since the complaints didn’t stop.

“Frank (Casares) feels he is gong to bear the brunt whether people are notified or not,” airport manager Tim Barth said in an August email to the City Council after a jump.

Quiet Skies charges that the noise affects thousands of Boulder County residents beneath Mile-Hi’s “flight box” — the area that Mile-Hi is allowed to fly in, to avoid Denver air traffic — and that on weekends, the “drone” can continue for more than 12 hours a day.

The airport has voluntary noise-abatement rules. City officials say that limiting Mile-Hi’s operating hours, making it change or modify its plane, or tightening the noise rules further, would run afoul of the Federal Aviation Administration’s authority.

Scott Rochat can be reached at 303-684-5220 or srochat@times-call.com.