The partial government shutdown is starting to affect US air travel.

Over the weekend, some airports had long lines at checkpoints, apparently caused by a rising number of security officers calling in sick while they are not getting paid.

Safety inspectors aren’t even on the job. A Federal Aviation Administration (FAA) spokesman said on Monday that inspectors are being called back to work on a case-by-case basis, with a priority put on inspecting airline fleets.

So far, the impact of the shutdown – entering its 18th day on Tuesday – has been most visible for some government buildings and national parks being closed or disrupted, and trash piling up on the National Mall in front of the US Capitol building. If the shutdown continues, food stamp recipients will go without aid.

By increasingly affecting air travel, however, the pain is being felt more widely.

Who is supposed to keep working?

About 10,000 air traffic controllers who work for the Federal Aviation Administration (FAA) and about 51,000 Transportation Security Administration (TSA) officers have been told to keep reporting to work because they are deemed essential. Those workers at airport checkpoints, control towers and FAA radar stations aren’t being paid.

Are they showing up to work?

TSA admits that more screeners are calling in sick at some airports, including Dallas-Fort Worth international. It gave few numbers but issued a statement last Friday saying that more have been missing work since the Christmas and New Year’s holidays. The TSA said the effect was “minimal”.

Then over the weekend, travelers reported longer checkpoint lines at some airports, including LaGuardia in New York, which focuses on domestic flights. On Monday, TSA tweeted that agents screened 2.22 million passengers nationwide on Sunday, which it called a “historically busy day due to holiday travel”. TSA said only about 220,000 travelers waited at least 15 minutes at checkpoints, while 0.2% – fewer than 5,000 – waited at least 30 minutes.

How will the TSA respond?

TSA spokesman Jim Gregory said officials are managing. “If we don’t have appropriations [government funds] by midweek or so, [officers] will miss their first paycheck. That’s obviously where it becomes more difficult,” he said.

Gregory said the agency has a team of officers who can go to airports facing a shortage, a tactic developed in case natural disasters prevented screeners from getting to work.

What about air traffic controllers?

About 1,900 air traffic controllers – nearly one in every five – are eligible to retire right now and it’s not clear how many of them will stick around. They won’t get paychecks later this week despite working over the holidays.

“I don’t know how long they’re going to stay on the job if they’re not getting a paycheck,” said Paul Rinaldi, president of the National Air Traffic Controllers Association.

There is an even larger group of recently hired trainees and apprentices and Rinaldi said the prospect of a long shutdown could lead some of them to take other jobs.

Will a shortage of controllers lead to flight delays?

The largest pilots’ union wrote to Donald Trump last week urging a quick end to the shutdown, which it said was threatening the safety of the nation’s airspace.

Rinaldi, the controllers’ leader, said safety is not being compromised, but that capacity to manage traffic could be reduced, leading to flight delays. Others see that as less likely.

“It would have to get pretty bad before the government said [to airlines]: ‘Hey, start scaling back your plans for service,’” said Richard Aboulafia, an aviation analyst. “You could see that in a worst-case scenario.”

Who is inspecting planes?

FAA spokesman Gregory Martin said the agency has been recalling inspectors for certain jobs including assignments at the airlines, as it did in previous government shutdowns.

“We’re going to continue to prioritize with the resources that we have,” Martin said. “Our focus is on the commercial air carriers and volumes of people they carry.”

Martin did not say how many inspectors are working or how the number of inspections being done compared with pre-shutdown levels.

Chuck Banks, one of those furloughed inspectors, said colleagues are being called in when an airline needs something, like a plane certified for flight. The routine, normal oversight of operations at airlines and repair shops is not being done, leaving companies to regulate themselves, he said.

“Do you like the fox watching the hen house?” he said. “Every day the government stays shut down, it gets less safe to fly.”

What other government services are affected?

The National Transportation Safety Board (NTSB) is delaying accident investigations and hearings. While there have not been any fatal airline crashes, the board has delayed other investigations, including an examination of a Florida highway accident that killed five children on their way to Walt Disney World.

NTSB representatives did not answer phone calls or reply to emails on Monday. A recorded message for the public affairs office said nobody would respond until the shutdown ends.



