Alaska Airlines has resumed flights after the failure of a critical piece of hardware forced the airline to ground all its planes for approximately three hours.

A hardware failure at an Alaska Airlines data center caused a system-wide “ground stop of flights” on Sunday night, the airline said. The airline has canceled more than 150 flights at various airports, including 64 Monday morning, with additional flight disruptions expected.

U.S. carrier Alaska Airlines resumed operations late on Sunday after briefly grounding all of its flights for about three hours due to an IT outage, marking the second time it has halted its fleet in just over a year.

Alaska Airlines passengers are still reeling on Tuesday after a system-wide IT outage left thousands stranded at airports across the country.

Alaska Air Group is giving its Tokyo flights operated by Hawaiian Airlines out of Seattle a big upgrade, with Hawaiian's Boeing 787 Dreamliner now slated for the route.