FARMINGTON — The U.S. Air Force has put on hold a proposal to fly low-altitude training missions over Northwest New Mexico and Southwest Colorado.

The Air Force expects to re-evaluate its training plans and decide in early 2013 whether to forge ahead with an environmental impact statement, a possible next step in the process.

The 27th Special Operations Wing at Cannon Air Force Base received about 1,600 comments from elected officials, residents, tribes, government agencies and private groups during a public comment period in late 2011 on a draft environmental assessment.

Plans for low-altitude training have raised noise and safety concerns from residents in both states.

The Air Force is evaluating whether a more detailed analysis is needed. If the Air Force decides to pursue an environmental impact statement, it would likely take a year or two before the flights would begin, said Cannon spokeswoman Lt. Stephanie Schonberger.

The proposal involves two of the nine aircraft types flown out of Cannon: the CV-22 Osprey, a tilt-rotor aircraft, and the MC-130J, a multi-engine support aircraft.

"We have some aircraft where flying low altitude is an important part of their mission," Schonberger said.

The area surrounding the base near Clovis lacks the terrain found in the Four Corners, she said.

"We don't have mountains here at Cannon," she said. The area is "relatively flat, so when we have to do mountainous training, we have to fly somewhere else."

The mountainous areas of the Four Corners are the nearest place to do that, she said.

Cannon is committed to working with communities to address their concerns, Schonberger said. "We want to be good neighbors to the people of Colorado and New Mexico," she said.

Local leaders largely expressed support for the training flights, in contrast to some organizations that sharply criticized the proposal.

Farmington Mayor Tommy Roberts, in a September 2010 letter to Col. Stephen A. Clark, commander of the wing, said the flights "can be totally successful if we both approach it with mutual respect and consideration for the needs of both the community and the service."

Roberts requested aircraft approach Four Corners Regional Airport from the west to avoid the more densely populated and noise-sensitive east side of Farmington. He also asked the Air Force to avoid operating in Farmington during the quiet hours of 10 p.m. to 6 a.m., and to adhere to federal standards regarding minimum altitudes.

Roberts said Thursday he had no position on the Air Force's delay of the training program. "That's certainly the Air Force's prerogative," he said.

A public hearing last fall on the program attracted little turnout, and Roberts said he had received no complaints from residents about the proposal.

Sen. Mark Udall, D-Colo., said the proposal "needed to be better coordinated with local communities and other airspace users."

"I appreciate the Air Force's decision to not move forward at this time with its low-altitude tactical navigation training based on the feedback it received from community members in southern Colorado, the central mountains and the Four Corners region," Udall said in a prepared statement. "We need to make sure that the Air Force's training plans are crafted in consultation with the military in Colorado and the communities they would affect."

The training flights would dip as low as 300 feet above ground level, which prompted concern from some residents and other military units that use the airspace, he said.