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 arenB次元官网网址檛 even on the job. A Federal Aviation Administration spokesman said 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 B次元官网网址� entering its 18th day on Tuesday B次元官网网址� has been most visible for some government buildings and national parks being closed, and trash piling up on the National Mall in front of the Capitol. If the shutdown continues, food stamp recipients will go without aid.

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

Here are some common questions about the shutdownB次元官网网址檚 impact on airports and travel, along with the answers:

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WHO IS SUPPOSED TO KEEP WORKING?

About 10,000 air traffic controllers who work for the Federal Aviation Administration and about 51,000 Transportation Security Administration 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 arenB次元官网网址檛 being paid.

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ARE THEY SHOWING UP?

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 Friday saying that more have been missing work since the Christmas and New YearB次元官网网址檚 holidays. The TSA said the effect was B次元官网网址渕inimal.B次元官网网址�

Then over the weekend, travellers reported longer checkpoint lines at some airports, including LaGuardia in New York. On Monday, TSA tweeted that agents screened 2.22 million passengers nationwide on Sunday, which it called a B次元官网网址渉istorically busy day due to holiday travel.B次元官网网址� TSA said only about 220,000 travellers waited at least 15 minutes at checkpoints, while 0.2 per cent B次元官网网址� fewer than 5,000 B次元官网网址� waited at least 30 minutes.

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HOW WILL TSA RESPOND TO NO-SHOWS?

TSA spokesman Jim Gregory said officials are managing. B次元官网网址淚f we donB次元官网网址檛 have appropriations by midweek or so, (officers) will miss their first paycheque. ThatB次元官网网址檚 obviously where it becomes more difficult,B次元官网网址� 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.

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WHAT ABOUT TRAFFIC CONTROLLERS?

About 1,900 air traffic controllers B次元官网网址� nearly one in every five B次元官网网址� are eligible to retire right now and itB次元官网网址檚 not clear how many of them will stick around. They wonB次元官网网址檛 get paychecks later this week despite working over the holidays.

B次元官网网址淚 donB次元官网网址檛 know how long theyB次元官网网址檙e going to stay on the job if theyB次元官网网址檙e not getting a paycheque,B次元官网网址� 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.

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WILL A SHORTAGE OF CONTROLLERS LEAD TO FLIGHT DELAYS?

The largest pilotsB次元官网网址� union wrote to President Donald Trump last week urging a quick end to the shutdown, which it said was threatening the safety of the nationB次元官网网址檚 airspace.

Rinaldi, the controllersB次元官网网址� 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.

B次元官网网址淚t would have to get pretty bad before the government said (to airlines), B次元官网网址楬ey, start scaling back your plans for service,B次元官网网址橞次元官网网址� said Richard Aboulafia, an aviation analyst. B次元官网网址淵ou could see that in a worst-case scenario.B次元官网网址�

An early test of the air traffic system could come around the Feb. 3 Super Bowl in Atlanta, when an influx of corporate jets and private planes will further crowd the sky above the nationB次元官网网址檚 busiest airport. Planning for handling that traffic has been put on hold, Rinaldi said.

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WHO HAS BEEN FURLOUGHED?

Workers who arenB次元官网网址檛 deemed essential. That ranges from technicians who maintain equipment used in airport towers to clerical staff. Federal aviation safety inspectors have also been furloughed.

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SO 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.

B次元官网网址淲eB次元官网网址檙e going to continue to prioritize with the resources that we have,B次元官网网址� Martin said. B次元官网网址淥ur focus is on the commercial air carriers and volumes of people they carry.B次元官网网址�

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.

B次元官网网址淒o you like the fox watching the hen house?B次元官网网址� he said. B次元官网网址淓very day the government stays shut down, it gets less safe to fly.B次元官网网址�

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WHAT OTHER GOVERNMENT SERVICES ARE AFFECTED?

The National Transportation Safety Board 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 Monday. A recorded message for the public affairs office said nobody would respond until the shutdown ends.

Some people who applied for Global Entry, a program that lets travellers get expedited clearance into the U.S., have had interviews cancelled. Gary Leff, who writes about travel on his View from the Wing blog, said that some airports are still processing applications.

The program is run by U.S. Customs and Border Protection. Spokespeople at the agency did not respond for comment.

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David Koenig, The Associated Press

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