United Airlines is resuming flights after a computer fault halted all U.S. departures for about two hours, disrupting travel for thousands of passengers in the second such setback since early June.
The U.S. Federal Aviation Administration disclosed the end of the grounding in a statement Wednesday after saying “automation issues” had forced a temporary suspension of U.S. takeoffs. The shutdown affected only mainline jets that had yet to take off, and planes already airborne continued to operate.
“We experienced a network connectivity issue this morning,” United spokesman Luke Punzenberger said by email, without elaborating.
The timing of Wednesday’s disruption, starting before 8 a.m. New York time and lasting until almost 10 a.m., caught fliers hustling for morning departures in the middle of the U.S. business week. At 9:40 a.m. New York time, 75 United flights had been delayed, the most among U.S. airlines, according to industry data tracker FlightAware.com.
The tardy takeoffs accounted for 3 percent of United’s daily total, according to FlightAware. The carrier’s hubs include some of the busiest U.S. airports, such as Chicago’s O’Hare, San Francisco International and New Jersey’s Newark Liberty.
At Boston’s Logan, “flights were held at their gates and are now reboarding,” the airport operator, Massport, said in an e-mailed statement.
United suffered a similar incident on June 2, when the world’s second-largest airline cited a lack of “proper dispatch information” that forced a halt in U.S. takeoffs for less than an hour. Planes in the air weren’t affected in that episode either.
United had no immediate comment beyond the initial e-mailed statement, and posted no advisories on the “Today’s Operations” section of its own website. The FAA offered no additional specifics beyond an advisory confirming the halt in departures.
“There is a ground stop on United flights due to a computer problem at the airline,” the U.S. agency said by e-mail. “Please contact United for more details.”
United fell 1.4 percent to $53.57, joining a retreat among the rest of the U.S. industry and broad equity indexes.
The carrier has struggled with occasional computer faults since the 2010 merger between former parent UAL Corp. and Continental Airlines created the current parent company, United Continental.
In February 2014, the system that handles check-ins and other passenger services failed, disrupting travel for about three hours at United hubs 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 (9,100 kilograms) 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.