United Airlines temporarily halted all takeoffs in the U.S. early Tuesday because of automation issues. Planes in the air weren’t affected.

The stoppage involving the world’s second-largest airline lasted for less than an hour, according to air traffic control notices from the Federal Aviation Administration. Chicago-based United said by e-mail, “We began delaying flights at approx. 8 a.m. CT to ensure aircraft departed with proper dispatch information. Flights are now departing.”

United didn’t immediately respond to requests for further comment beyond the e-mailed statement. A spokesman for the FAA wasn’t immediately available to discuss to stoppage.

United has struggled with occasional computer faults since the 2010 merger between former parent UAL Corp. and Continental Airlines created the current United Continental Holdings Inc.

In February 2014, the system that handles check-ins and other passenger services failed, disrupting travel for about three hours at United hub airports including San Francisco, Washington and Chicago. The previous month, a malfunction stranded pilots and caused about 1,500 cancellations.

United added extra precautions in 2012 after a computer breakdown caused one of its planes to take off about 20,000 pounds heavier than pilots believed, creating difficulties in getting the jetliner airborne.

Three other computer glitches that year at United also ensnared thousands of travelers with tardy flights.