Delta Air Lines' flights schedules had largely returned to normal Wednesday after a "technical issue" forced the carrier to briefly ground all of its domestic flights Tuesday.
Only three of the carrier's mainline flights had been canceled as of 2:30 p.m. EDT while about 230 combined departures and arrivals were delayed, according to flight-tracking service FlightAware. The delays accounted for just about 7 percent of Delta's entire daily schedule.
That's a relatively low number but is above normal for Delta, consistently one of the USA's most on-time carriers.
But many of the airline's Tuesday flights were affected after a systems outage forced Delta to hold its domestic flights on the ground across the nation for about an hour Tuesday. The ground stop applied only to domestic flights, and flights already in the air continued on to their destinations as normal. Delta said the stop applied only to its mainline flights and not to the hundreds operated by its regional affiliates that fly smaller jets.
FlightAware counted only three cancellations on Delta's mainline operations Tuesday, but more than 675 flights were delayed. That number meant about one out of every five Delta flights was late by Tuesday evening.
After customers began complaining of delays on social media shortly before 8 p.m. EDT on Tuesday, Delta acknowledged a technical glitch.
By 9:28 p.m. EDT, Delta said in an update that the issue had been resolved.
TODAY IN THE SKY: Trip report: Reviewing the Delta One Suite with sliding privacy doors
"Delta teams have restored all IT systems after a technology issue briefly affected some of our systems this evening," Delta's statement said. "All groundstops have been lifted."
Delta advised customers flying on Wednesday to check ahead on the status of their flights but said it did not expect major disruptions.
"Additional flight delays and the impact on Wednesday morning’s schedule are expected to be minimal. Delta apologizes to its customers for this inconvenience," the airline said.
Delta has not specified a cause of the outage, saying only that its teams "are investigating the root cause of the technology issue."
During the hour or so that flights were being held, Delta faced queries from delayed passengers about the problem. In response, Delta confirmed the technical issues were systemwide, with domestic flights on a ground stop.
International flights were not affected.
Prior to the resolution, Delta confirmed the incident in a statement posted to its website.
"Delta IT teams are working diligently to address a technology issue impacting some of our systems," the company said. "We have issued a Delta groundstop as we work to bring systems back up as quickly as possible. There has been no disruption or safety issue with any Delta flight currently in the air. We apologize to all customers for this inconvenience. "
Contributing: Dustin Barnes of The Tennessean newspaper in Nashville.
TODAY IN THE SKY: Delta shows off new 'flagship' Airbus A350 in Atlanta
TODAY IN THE SKY: Delta shows off first Boeing 777 retrofitted with new cabin interior