Southwest Airlines said there is no evidence that a cybersecurity breach led to the technical failures that delayed flights and stranded passengers across the country on Sunday.
According to the airline, over 800 of Southwest’s roughly 3,300 flights were pushed back on Sunday. Videos and social media posts across the country showed passengers waiting in long lines as Southwest was unable to print boarding passes or electronically check in passengers.
Sunday’s incident is just the latest in a long string of technical glitches at U.S. airlines that have grounded flights and shut down check-in systems.
American Airlines in September faced “connectivity issues,” causing it to halt all flights for nearly two hours at three of its major U.S. hubs.
In July, a router error caused United Airlines to hold flights, because it could not check in or board passengers.
While there is no evidence the incidents were linked to security breaches, hackers have increasingly targeted airlines and the air traffic control system, causing suspicions every time another technical issue grounds flights.
The Federal Aviation Administration, which oversees U.S. flight routes, said digital intruders spread malicious software through their network earlier this year.
Suspected Chinese hackers have also stolen detailed travel records from American Airlines and United Airlines.
And overseas, Polish airline LOT had to ground several planes after a cyberattack took out its computer system that issues flight plans. The airline warned that anyone could be hit by such an attack, a sentiment cybersecurity experts share.
“I don’t think these kinds of attacks ... are a huge surprise to security information insiders,” Tim Erlin, director of risk strategy at Tripwire, told The Hill in August. “We see these kinds of weakness and have seen them for years.”