The flight reductions imposed during the government shutdown are now over; the Federal Aviation Administration lifted them early Monday morning. Forty major U.S. airports and more than 5 million travelers were affected by related air travel delays and cancellations.

And now that federal workers, including air traffic controllers, are back to being paid for their work, some are calling to detach part of the FAA’s funding from the annual funding fights in Congress.

There was already a shortage of air traffic controllers even before the shutdown. Now, even with it over, “These interruptions keep making it more and more difficult to train new air traffic controllers and to finance and adequately install the systems needed to modernize the air traffic control system,” said Jeff Davis, a senior fellow at the nonpartisan Eno Center for Transportation.

Other places, like Canada and several European countries, don’t have this problem, according to Rick Geddes, a professor of infrastructure policy at Cornell.

“The problem with air traffic control in the United States is that it's subject to the vagaries of congressional appropriations processes, and that makes it subject to political forces,” Geddes said.

Geddes and others argue for a different model of funding, like the one in Canada, that doesn’t rely so much on government funding and instead leans more on user fees from the airlines. Airlines already have to collect fees to help fund the FAA, but that money can’t be used automatically during a shutdown.

“There is discussion of switching to a user fee where they charge the airlines directly for the number of hours in the air, number take off and landings, etc., instead of the current system, because the current system is very much about the number of people in the airplane,” Davis said.

But opponents of that kind of change say it would serve to benefit larger airlines at the expense of smaller operators and private aviation.

The FAA did not respond to a request for comment by press time.

Ed Bolen, president of the National Business Aviation Association, said the focus should instead be on implementing the FAA’s multi-billion-dollar plan to modernize the whole system over the next few years.

“Parts of the air traffic control system are antiquated so we have a clear plan from the FAA for phasing in the building of a brand-new air traffic control system, and that includes surging the number of air traffic controllers,” Bolen said.

Who may need a bit more encouragement to sign up for the job after watching what just went down.