All United Airlines flights in the US have been grounded in the country due to a computer system glitch on 8 July.
The Federal Aviation Administration (FAA)'s website said that all UA flights were temporarily grounded due to "automation issues".
United told CNBC news that it "experienced a network connectivity issue" affecting all flights and was working to fix the issue.
Customers voiced their frustration at the nationwide incident:
This is not the first time that computer problems cause a meltdown at United systems.
Earlier in June, another technical glitch caused all flights to be grounded temporarily. They were restored about half an hour later.
United tweeted that it delayed flight "to ensure aircraft departed with proper dispatch information. Flights are departing now."
Charles Hobart, a United spokesman, said the airline is "accommodating our customers to their destinations."