The Federal Aviation Administration gounded all United Airlines flights temporarily Tuesday morning due to unspecified “automation issues.” According to the airline, flights were delayed in order to ensure that the flight dispatch system was working properly.

The FAA issued the temporary advisory around 9:25 a.m. EDT on Tuesday morning, but it was lifted just a few minutes later.

“United began delaying flights at approximately 8 a.m. CT [U.S. Central Time, one hour behind Eastern Time or EDT] to ensure aircraft departed with proper dispatching information,” United Airlines spokesman Charles Hobart told International Business Times in a statement. “We resumed departures at about 8:40 CT and are accommodating our customers to their destinations.”

Many passengers, who were stranded on flights that were sitting on the tarmac, took to Twitter to bemoan the delay.