It’s not a great week to fly. On Friday, the Federal Aviation Administration canceled hundreds of planned flights at 40 high-traffic US airports due to a record-long government shutdown that has affected air traffic controllers. The controllers are working without pay and were already shorthanded even before the disruption began on Oct. 1. Flight cuts began at 4% Friday, will bump up to 5% Saturday and ramp up to 10% next week.

According to CNN, airlines canceled more than 800 flights as of about 4:30 a.m. ET Friday, reportedly four times the number of flights canceled the day before.

NBC News reports that several airports across the country have issued staffing triggers, indicating that they lack sufficient staff to operate their regular schedules.

There’s no set end time for the flight reduction, which could spread beyond those 40 airports. Looming in the background is the high-volume holiday travel season. 

A representative for the FAA did not immediately respond to a request for comment.

Earlier in the week, airline employees had already begun bracing for potential flight disruptions. On Wednesday morning, CNET Senior Editor Corinne Reichert was buckled into her seat on a Southwest Airlines aircraft, getting ready for an in-state flight in California. While on the runway, the pilot informed passengers that it was unclear whether the shutdown would affect that day’s flights and advised: «Keep your fingers crossed.»

Read on below for what to know about traveling amid the government shutdown. And for other travel tips, see our smart travel checklist, guidelines on travel essentials to pack and how to avoid TSA checkpoint headaches.

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Is my airport affected?

Almost certainly. These are the 40 airports currently affected, listed in alphabetical order by their three-letter airport code.

• Anchorage International (ANC)
• Hartsfield-Jackson Atlanta International (ATL)
• Boston Logan International (BOS)
• Baltimore/Washington International (BWI)
• Charlotte Douglas International (CLT)
• Cincinnati/Northern Kentucky International (CVG)
• Dallas Love (DAL)
• Ronald Reagan Washington National (DCA)
• Denver International (DEN)
• Dallas/Fort Worth International (DFW)
• Detroit Metropolitan Wayne County (DTW)
• Newark Liberty International (EWR)
• Fort Lauderdale/Hollywood International (FLL)
• Honolulu International (HNL)
• Houston Hobby (HOU)
• Washington Dulles International (IAD)
• George Bush Houston Intercontinental (IAH)
• Indianapolis International (IND)
• New York John F Kennedy International (JFK)
• Las Vegas Harry Reid International (LAS)
• Los Angeles International (LAX)
• New York LaGuardia (LGA)
• Orlando International (MCO)
• Chicago Midway (MDW)
• Memphis International (MEM)
• Miami International (MIA)
• Minneapolis/St Paul International (MSP)
• Oakland International (OAK)
• Ontario International (ONT)
• Chicago O’Hare International (ORD)
• Portland International (PDX)
• Philadelphia International (PHL)
• Phoenix Sky Harbor International (PHX)
• San Diego International (SAN)
• Louisville International (SDF)
• Seattle/Tacoma International (SEA)
• San Francisco International (SFO)
• Salt Lake City International (SLC)
• Teterboro (TEB)
• Tampa International (TPA)

When will delays end?

The flight reductions begin with Friday’s flights. There’s no word on how long they’ll last, but a worrisome sign is that there’s no end in sight for Congress to act to end the government shutdown.

Transportation Secretary Sean Duffy told CNBC that he could «shut the whole airspace down» if the legislative standstill continues.

He also said that even if the government shutdown ends, flights won’t return to normal instantly, as it will take time to restore staffing levels and schedules.

What should I do before I go to the airport?

Download relevant apps

Load any apps related to your airline or airport onto your phone — they can send you information about delays and cancellations.

Print or download your boarding pass at home

Even if your flight seems unaffected, be prepared for long security and ticket lines, as well as possible changes to your flight schedule. If you can, print or download your boarding pass in advance to save time. 

Shorten your time in the security line

Check to see if your airport has a website that displays the shortest security lines and their corresponding wait times. If you have TSA PreCheck or another expedited security service, now is the time to use it. When booking a flight, make sure your TSA PreCheck number is entered, or you may not see the important logo appear on your boarding pass. 

Numerous airports — including SeaTac, Denver, MSP, JFK, LAX, Phoenix, and Houston’s George Bush Intercontinental — offer free programs that allow you to reserve a specific time in a security lane and be ushered right to the front.

Stay on top of delays

Bookmark the National Airspace System Status site and check it to see if there are weather or other delays at the airport you’re using.

What if my flight is canceled?

Don’t waste your time in line

Consult your airline to see if they can reschedule you or refund your payment. You may have to stand in a long line at a service counter, but while in line, you can try rebooking online or calling the airline’s support number. Some travelers use social media to send messages to their specific airline, and if those accounts are monitored, it’s possible you’ll get a response that way. And we like this smart suggestion from PBS: Look up your airline’s international support number and call it, because it might be less busy. (At least until word of this trick leaks out.)

Treat the employees with respect

When you finally reach an airline employee for help with rebooking, be patient. This isn’t their fault, and they’re more likely to help you if you’re understanding. 

Be flexible

You’ll have better luck if you’re flexible with times and dates, and you might ask to be rebooked on a partner airline if there’s room available. 

Can you get there another way?

You can also consider canceling your flight and choosing to drive or take some other form of transportation if that fits your circumstances, but if your sister’s wedding is tomorrow, you might not have a choice.

What are the airlines saying?

Delta Airlines said in a statement that it will work to «minimize customer impact» and will allow passengers «additional flexibility» when it comes to changing or canceling flights without penalty. Details on fee waivers are here.

American Airlines made a similar statement about waiving penalties.

«To provide additional flexibility during the impacted travel period, customers whose flights are cancelled for any reason or who choose not to travel will be able to change their flight or request a refund without any penalty,» American Airlines said.

A United Airlines statement, directed to employees, followed suit. «Any customer traveling during this period is eligible for a refund if they do not wish to fly — even if their flight isn’t impacted,» the statement said. «That includes nonrefundable tickets and those customers with basic economy tickets.»

Southwest has a similar statement that says «all Southwest Customers, with travel booked through Wednesday, Nov. 12, may adjust their travel plans at no cost, or receive a refund if they choose not to travel, regardless of whether their flight is affected.»

If you’re on another airline, it’s best to check the website for a similar notice. Note that airlines are not required to provide accommodations in a hotel or cover other expenses resulting from travel delays.