Congress is making progress toward ending the longest government shutdown in U.S. history, a deadlock that has forced the cancellation of thousands of flights across the United States.

But even if lawmakers finalize the a deal this week, travelers shouldn’t expect an instant return to normal at the nation’s airports.

Flights have already been reduced at 40 of the country’s busiest airports to offset air traffic controller shortages, leading to a wave of uncertainty for travelers. Experts warn those disruptions will linger long after the shutdown officially ends.

"There's going to be extensive disruption across the entire nation’s air transportation system," Henry Harteveldt, and airline industry analyst and president of Atmosphere Research Group, an independent travel analytics firm, told USA TODAY. And the consequences could last longer than the shutdown.

Why flight cuts will continue even after the government reopens

Even if the shutdown ends soon, travelers shouldn’t expect those cuts to disappear overnight.

Experts say the impact on air travel will stretch well beyond the shutdown's end as airlines work to untangle complicated flight schedules and recover from staff shortages that can’t be fixed instantly.

"It's going to be a step-up, phased-in approach to cutting flights," Harteveldt said. "For an airline to be told by the government they’ve got 36 or so hours to start dismembering their carefully built flight schedules doesn’t give airlines a lot of time."

Why recovery won't be immediate

When flights are canceled, it’s not just one plane or route affected. "Airlines have to consider the flow of aircraft and crew when they cancel flights,” said Ahmed Abdelghany, associate dean for research at the David B. O'Maley College of Business at Embry-Riddle Aeronautical University. "If you cancel both flights of a round-trip loop, the aircraft and crew end up in the right place later. That avoids stranding planes and crew, which is what makes recovery possible."

Major hubs like Hartsfield-Jackson Atlanta International, Chicago O’Hare International and Los Angeles International are seeing widespread impacts, but travelers connecting through other airports are also likely to feel the effects. Shye Gilad, a professor of practice in management at Georgetown University and a former airline pilot, said connecting passengers "are potentially even more at risk, more likely to experience fare increases, less frequent flights, fewer options, and much longer layovers."

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Delays could linger for weeks

Even after government operations resume, the FAA's ongoing staffing crisis may keep limits in place. Transportation Secretary Sean Duffy said the agency is short between 1,000 and 2,000 air traffic controllers, with retirements accelerating during the shutdown.

"I used to have about four controllers retire a day before the shutdown," Duffy told CNN. “Now up to 15 to 20 a day are retiring.”

That shortage means capacity restrictions could remain until staffing stabilizes. "It's not that the day the shutdown ends, this capacity restriction is lifted," said Hopper analyst Hayley Berg. "They're not going to lift this capacity reduction until air traffic control and the FAA are operating at the staffing level they need – and that might not happen immediately."

Abdelghany agrees that the ripple effects will take time to unwind. “Even if the government reopens, recovery will still take time,” he said. “Some passengers will have to be refunded and removed from the system because capacity simply cannot absorb everyone. The severity and duration of this reduction will determine how long recovery takes.”

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Longer-term travel ripple effects

Experts warn that some Thanksgiving travel plans could still be disrupted even if the shutdown ends this week. "That could mean more traffic on the highways, other modes of transport, or simply people not being able to travel at all," Gilad said. And beyond travelers, Harteveldt said, "The financial impact will be felt not just by airlines and airport concessions but also by the destinations that see fewer visitors."

(This story has been updated with new information.)

This article originally appeared on USA TODAY: Why flights won't go back to normal immediately after the shutdown ends

Reporting by Eve Chen, USA TODAY / USA TODAY

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