This might seem cataclysmic—a worldwide outage for an airline—but these glitches are becoming a familiar hassle for travelers. Southwest Airlines in late July said it grounded flights because of a system outage, less than a year after a similar software problem had delayed hundreds of flights. Also last month, GoJet, which operates flights for Delta and United Airlines, cancelled or delayed flights because of an outage. A companywide malfunction at United last year grounded hundreds of flights.

The problem is especially severe for Delta, which operates more than 5,000 flights a day. The airline offered refunds to passengers experiencing severe delays.

The outage is the latest reminder of how airlines’ reliance on computer systems—seemingly without effective backup systems—can cascade into chaos for travelers when something goes awry.

Perhaps instead of extra legroom or uncensored in-flight entertainment, passengers should start choosing their carrier based on their backup servers.

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