Southwest Airlines passengers lost a chunk of Friday morning to a computer outage. A problem at the airline's tech vendor, Amadeus, knocked out the systems used to check in travelers, print boarding passes and scan them at the gate.

Southwest kept flying by doing it the old way. "The airline continued to check baggage and board flights manually while full functionality was restored," the company said.

The trouble began shortly after 8 a.m. Eastern, the New York Post reported. Lines spilled out of terminals. At Dallas Love Field, boarding passes would not print or scan, the city's aviation department said. One traveler said gate agents asked people to show screenshots of their boarding passes, TheTravel reported. In Denver, a passenger said staff announced that all planes on the ground had been stopped.

Some Southwest flights were temporarily grounded, the New York Post reported. Amadeus blamed an unnamed outside tech provider and apologized.

By 9:15 a.m., nearly 900 Southwest flights were delayed and 43 canceled, according to FlightAware, The Dallas Morning News reported. Systems came back at 10:15 a.m., Simple Flying reported. But the delays kept piling up. By 5 p.m., more than 1,500 Southwest flights had been delayed, about a third of the airline's flights that day.

What should travelers do? If your flight was delayed or canceled, check the Southwest app or website for rebooking. Keep receipts for meals or hotels, and ask the airline about refunds.

Southwest has a long record of tech troubles. In December 2022, a winter storm overwhelmed its crew-scheduling systems. The meltdown led to about 16,900 cancellations and a record $140 million federal fine. A firewall failure in April 2023 caused a nationwide ground stop. The airline says it has since spent more than $1 billion on upgrades.

What we know: An Amadeus outage forced manual boarding and delayed hundreds of Southwest flights.
What we don't: Which outside provider failed, and how many travelers missed connections.