Last Updated Jul 8, 2015 1:38 PM EDT
Computer issues that on Wednesday grounded all United Airlines (UAL) flights have been resolved, with a ground stop lifted, federal aviation authorities said.
"We experienced a network connectivity issue this morning," United said by email. "We are working to resolve this and apologize to our customers for any inconvenience."
United officials later told CBS News, "An issue with a router degraded network connectivity for various applications, causing this morning's operational disruption. We fixed the router issue, which is enabling us to restore normal functions."
It is the second time in as many months that United flights were delayed because of computer glitch. About a month ago, the carrier held flights for about 40 minutes when their dispatch system went off line.
United told CBS News that the airline had just over 800 delays, and nearly 60 cancellations, including regional flights. "We are restoring regular flight operations, but some customers may experience residual delays today," the airline said.
Flights already aloft remained in operation, according to Flightradar24, a website that tracks airplanes.
United's stock declined 2.5 percent, or $1.35, to $52.96 in midday trading.
Word that United flights had ceased first spread on Twitter, with many passengers reporting they had been delayed.