One of the facilities on the closure list is at Ogden-Hinckley Airport in Utah, where air traffic controllers keep planes safely separated from the F-16s screaming in and out of nearby Hill Air Force Base and flights using Salt Lake City International Airport.
"There's going to be problems," said Ogden airport Manager Royal Eccles. "There will be safety concerns and ramification because of it."
Opponents of the closures are also warning of possible disruptions to medical transport flights and flight schools training the next generation of pilots.
The 149 air traffic facilities slated to begin closing on April 7 are all staffed by contract employees who are not FAA staffers. There were 65 other facilities staffed by FAA employees on the preliminary list of towers that could be closed. A final decision on their closure will require further review, the FAA said.
The agency is also still considering eliminating overnight shifts at 72 additional air traffic facilities, including some at major airports like Chicago's Midway International and General Mitchell Airport in Milwaukee. There was no word Friday on when that decision will come.
The targeted towers are located in nearly every state.
Hundreds of small airports around the country routinely operate without controllers. Pilots flying there are trained to watch for other aircraft and announce their position over the radio during approaches, landings and takeoffs.
But the overall air system's safety is built on redundancy. Taking away the controller's extra set of eyes is like removing stop signs or traffic lights from city intersections and forcing drivers to be more vigilant and cautious, said Paul Rinaldi, president of the National Air Traffic Controllers Association.
"That's what the pilot is going to have to do now," said Rinaldi, whose group represents nearly 15,000 FAA-employed controllers as well as some staff at privately run contract towers. "A pilot is now going to have that extra duty of making sure that everybody seems to be doing the right thing on a crowded" radio frequency.