WASHINGTON (Reuters) -A group representing major U.S. airlines said it is imperative the Federal Aviation Administration accomplish some "quick wins" in the $12.5 billion overhaul of the aging air traffic control system, according to a letter seen by Reuters on Wednesday.

Airlines for America CEO Chris Sununu in a previously unreported letter to Transportation Secretary Sean Duffy said the FAA should quickly implement airspace modernization designs, buy simulators to improve controller training, lay telecommunications fiber and buy new radars and radios.

"These initial wins will create tangible benefits for the traveling and shipping public, help coordinate messaging on progress and boost optimism on the prospects of moving the project to completion," Sununu wrote.