Financial uncertainty has made it more difficult for the Federal Aviation Administration to fight delays nationally and has snagged projects that would help congested airports, according to an analysis by the U.S. Government Accountability Office.

The federal government shutdown in 2013, as well as a 2011 furlough of thousands of FAA workers without pay, delayed thousands of flights in recent years and made it more difficult to install a high-tech navigational system that would help busy New York airports.

The navigational system, called NextGen, lets pilots fly more precise routes, will help airports such as JFK and LaGuardia cut down on delays and use their space more efficiently.

New York City airport advocates were concerned by the analysis.

"This report confirms what we've long known: that air traffic improvements are not a priority for Washington. And the longer we have to wait for NextGen, the more delays it means," said Joe Sitt, the chairman of the advocacy group Global Gateway Alliance.