Airlines said a computer-system fault delayed departures across the U.S. early Monday, showing how even brief technical problems can quickly affect much of the nation’s air-travel network.
The Federal Aviation Administration said several airlines experienced issues with widely used flight-planning software that prevented some flights from taking off for up to two hours. Delays hit most major U.S. carriers including Southwest Airlines Co. and SkyWest Inc., an operator of commuter flights for United Continental Holdings Inc.,...
Airlines said a computer-system fault delayed departures across the U.S. early Monday, showing how even brief technical problems can quickly affect much of the nation’s air-travel network.
The Federal Aviation Administration said several airlines experienced issues with widely used flight-planning software that prevented some flights from taking off for up to two hours. Delays hit most major U.S. carriers including Southwest Airlines Co. and SkyWest Inc., an operator of commuter flights for United Continental Holdings Inc., Delta Air Lines Inc. and others.
Airlines said the computer system provided by AeroData Inc. helps dozens of carriers calculate aircraft weight and balance to determine fuel needs and takeoff and landing requirements.
Scottsdale, Ariz.-based AeroData didn’t respond to requests for comment.
Southwest suffered the most delays, with 25% of its flight schedule affected, according to tracking service FlightAware. Southwest has also been battling unrelated aircraft maintenance issues and the grounding of its fleet of Boeing Co. 737 MAX jets after two recent crashes of that aircraft at other airlines.
SkyWest had 14% of its flights delayed. American Airlines Group Inc. said its main operations were unaffected but that its commuter services suffered delays. JetBlue Airways Corp. and Alaska Air Group Inc. also experienced disruptions.
AeroData’s weight-and-balance monitoring system has helped to automate some of the work flight planning, improving efficiency and on-time departure rates for many carriers. Southwest said it is the primary tool it uses to handle loading passenger and cargo information. American, Delta and United said their mainline operations used a different system.
Airlines use a variety of in-house and vendor services to calculate aircraft weights from passengers and cargo to determine takeoff and landing requirements. AeroData, one of the largest outside providers, supports more than 100 carriers from three data centers in Arizona and Colorado, according to marketing material. One customer said AeroData had added a number of backup systems in recent years.
U.S. airlines have suffered spates of technology hiccups before. Southwest in 2016 was forced to cancel over 2,300 flights over four days when a computer router failed. Delta, a month later, had to cancel more than 2,000 flights when a power surge and fire took down a computer system. United and American subsequently also suffered flight delays that disrupted operations.
And the airline reservation and passenger-handling system provided by Sabre Corp. to many airlines experienced five outages in 2017. Sabre experienced a brief disruption last week as well, disrupting online bookings and delaying check-ins at some carriers.
Similar problems have occurred overseas. British Airways two years ago also faced multiple days of disruption because a power surge took down an IT system.
U.S. airline delays affected 25% of flights nationwide in 2014 but have since fallen to 17% of the schedule last year, while the number of flights has grown overall, according to the Bureau of Transportation Statistics. Around a quarter of delays last year were attributed to airline-related problems.
On one American Airlines flight scheduled to depart for St. Louis from New York’s LaGuardia Airport on Monday morning, passengers said after they boarded that their flight would be delayed due to a “systemwide computer outage.”
About an hour later, the captain said staff were getting news reports that other airlines were delayed as well. “We are not the only ones,” he told the passengers. “And it is coming back online but it may be another 15-20 minutes before we get our paperwork.”
—Doug Cameron and Corinne Ramey contributed to this article.
Write to Robert Wall at robert.wall@wsj.com and Alison Sider at alison.sider@wsj.com