Alaska Airlines warned of more flight disruptions on Monday after an unexpected failure of a critical piece of hardware at its data centers late Sunday forced it to halt all flights for about three hours.

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.

Alaska Airlines on Sunday, July 20 grounded all of its flights over a tech issue, but resumed its flights shortly after in the early hours of. However, the IT issue that caused the delays for travelers could end up causing more issues in the near future,