A near-collision in midair last year prompted the Federal Aviation Administration to quietly change its takeoff procedures to route more flights -- and noise -- over south Minneapolis neighborhoods outside the official noise zone for Minneapolis-St. Paul International Airport.
The pattern is likely to be permanent.
For several months, neighbors and public officials have been frustrated at their inability to get an explanation for the increased noise or a prediction as to how long it will last. The FAA had cited wind conditions and airline scheduling, but residents were skeptical that those factors fully explained the prolonged increase in noise.
"There's clearly something going on, and nobody's 'fessing up to the neighborhoods what it is and why it is," state Rep. Jim Davnie, a DFLer who represents some of the area, said last week. "I've been in office 11 years, this is the first time that airport noise has come up as an issue."
The FAA confirmed Wednesday that the near-crash of a passenger jet and a cargo plane last September prompted the new procedure to improve safety.
"We had a previous procedure ... that we no longer use," FAA spokeswoman Elizabeth Isham Cory said. "It was discontinued after an operational error."
The noise you hear
Relatively isolated from airplane noise in past years, the Keewaydin and Ericsson neighborhoods have experienced a sharp and sustained rise in air traffic, according to the Metropolitan Airports Commission. Departures rose 25 percent this year over the same period in 2010.