U.S. airlines started returning to full service early Monday after a disruption of data they needed for takeoff caused delays across the country.

The intermittent problem lasted about two hours, according to American Airlines Group Inc., which experienced delays at some of its regional affiliates. Delta Air Lines Inc., Southwest Airlines Co. and United Continental Holdings Inc. also were affected. The Federal Aviation Administration said the outage had been resolved.

The issue involved weight and balance information provided by AeroData Inc. that is needed for flight planning, the agency said in a statement. The interruption lasted for about 48 minutes starting at 5:24 a.m. in Washington, the FAA said. Mainline and regional carriers were affected to varying degrees.

Details of an aircraft’s weight and how it’s distributed on board is required before a flight can take off. Such calculations also must be approved by airline dispatchers in remote offices, complicating flight schedules if communications or computer systems crash. A call to AeroData wasn’t immediately returned.

United said 150 flights by its United Express regional carriers were delayed. “Some flights that were affected have departed, and we’re working to get all affected flights back on schedule,” the carrier said in a statement. Delta said it didn’t expect any cancellations among the Delta Express flights delayed by the outage.

Southwest had 585 delays at 9:06 a.m. in New York, according to flight tracker website FlightAware.com, while JetBlue had 199.