NEW YORK (AP) — United Airlines suffered a brief system outage and the Federal Aviation Administration issued a ground stop of less than an hour for all United flights. The ground stop order was lifted before 8 a.m. at the airline’s request, according to an advisory issued by the FAA.

The airline said in a tweet that “We experienced a system outage this morning, but everything is up and running and operations have resumed.” It is unclear how many delays have happened, or if there are any related cancellations.