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.

Alaska Airlines has revealed that an "unexpected failure" of a critical piece of hardware caused an IT outage that led to its entire fleet being temporarily grounded on Sunday.Thousands of passengers have been affected by knock-on delays and cancellations continuing into Monday as the airline scrambles to resume service.

Alaska Airlines has resumed operations following an undisclosed technical error affecting its entire system for approximately three hours.