United Airlines Inc. has resumed flights after a computer problem halted all U.S. departures for about two hours, disrupting travel for thousands of passengers in the second such setback since early June.
"An issue with a router" caused the failure, United said Wednesday in a statement without giving details.
The shutdown affected only mainline aircraft that were still on the ground, according to the U.S. Federal Aviation Administration. The grounding ran from about 8 a.m. until almost 10 a.m. (ET), snarling a busy travel period and spilling over into hundreds of tardy takeoffs later in the day. By noon (ET), 444 United flights had been delayed, according to data tracker FlightAware.com. That was about 20 per cent of United's daily total.
"I am more frustrated than anything," said Jay Mitchell, an executive-search consultant who was booked to fly to Houston from Fort Lauderdale, Fla. A friend alerted him that United's planes had been ordered parked, and he abandoned his trip to the airport.
"Almost half" of his United flights in the past two to three months have been delayed to some extent, according to Mitchell, who said he flies almost weekly. "It's gotten pretty consistent to where I now have to plan a buffer around my travel time."
United said affected travellers would be able to get a waiver to rebook trips without penalty. The world's second-largest airline suffered a similar incident on June 2, when a lack of "proper dispatch information" forced a halt in U.S. takeoffs for less than an hour.
United fell 2.9 percent to $52.75, joining a retreat among the rest of the U.S. industry and broad equity indexes.
The Chicago-based 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.