Alaska Airlines temporarily grounded its fleet late Sunday. It’s a reminder of the threat posed to the sector by tech outages.

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 grounded.

"At approximately 8 p.m. Pacific on Sunday, Alaska Airlines experienced an IT outage that’s impacting our operations. We requested a temporary, system-wide ground stop for Alaska and Horizon Air flights until the issue is resolved," the airline said in a statement Sunday evening. The airline said it resumed operations at about 11 p.m. PT.