The airline confirmed that the failure of a third-party piece of hardware grounded flights, underscoring the fact that even systems that are multiply-redundant can go down.

The failure, in the airline’s computer network, forced it to ground flights Sunday night for about three hours. The outage, tied to third-party equipment, yielded about 200 cancelled flights. A replacement is underway.

The outage was a result of an unexpected hardware failure in Alaska's data centers and is not related to cybersecurity issues, the airline said.