The US Federal Aviation Administration (FAA) issued a ground stop advisory on Wednesday for Alaska Airlines, saying: “All Alaska mainline and subcarrier flights ground stopped.”

In a separate statement, the FAA said the carrier “asked the FAA to pause the airline’s mainline departures nationwide”. It did not provide a reason for the stoppage. CNBC reported that the problem may have been an IT issue and that the airline’s system used to calculate weight and balance for flights was not functioning correctly.

Alaska said in a statement: “This morning we experienced an issue while performing an upgrade to the system that calculates our weight and balance. A ground stop for all Alaska and Horizon flights was instituted at approximately 7.50am PT. We’re working to resolve the issue as quickly as possible. We apologize for the inconvenience and encourage guests to check the status of their flights on alaskaair.com or the Alaska App prior to heading to the airport.”

Responding to passenger complaints on social media platform X, the airline said it was working on getting people moving as soon as possible.

The FAA advisory said that flights for SkyWest, which provides regional service for Alaska Airlines and others, were excluded.

The stoppage comes the same day as a Boeing whistleblower testifies before Congress. The day before, he called on the aviation giant to ground its 787 Dreamliner aircraft after warning they were at risk for premature failure.

In January, a door flew off a Boeing plane mid-flight, prompting increased scrutiny from airlines and regulators.