All United Airlines flights nationwide were grounded on Wednesday after the company’s computer system suffered a technical glitch, according to the Federal Aviation Administration.
The Federal Aviation Administration said the "automation issues" that caused the grounding of the flights have been resolved.
"We experienced a network connectivity issue this morning," the United said in a statement earlier on Wednesday. "We are working to resolve this and apologize to our customers for any inconvenience."
Over 3,000 flights were affected while delays could impact services to 235 domestic and 138 international destinations.
A similar incident with United Airlines occurred on June 2.
Some travellers took to social media to vent their frustration with the situation.
Passengers at airports from Albuquerque, New Mexico, to Washington DC and Florida complained of system backlogs and long lines.