Southwest Airlines grounded its flights Monday night on account of an issue with its weather data provider.

“While Southwest Teams and the vendor worked to restore connectivity, we implemented a ground stop to protect the Safety of our Crews and Customers,” the aircraft said in an explanation Monday late evening declaring flight activities had continued.

The airline had counted 1,398 delays — the greater part of any aircraft in the world, as indicated by Flightaware, a site that tracks global airline cancellations and different issues.

In replies to a barrage of complaints on its official Twitter page, airline delegates apologized to clients and said the organization was attempting to determine the issue “ASAP.”

Pictures showed a packed airport concourse in Phoenix and Southwest planes that seemed, by all accounts, to be sitting on the tarmac in Denver.

“NEWS from my life,” tweeted Sheryl Gay Stolberg, a New York Times reporter. “On board a @SouthwestAir flight from Ft Myers to Baltimore but can’t take off. Been holding at gate for 45 minutes. Entire @SouthwestAir fleet grounded because the company’s weather monitoring system is down.”

Another said she had been deferred for over three hours in Chicago. Hollywood Burbank Airport said it had suspended all Southwest takeoffs over a “network” issue, however it later said the flights were taking off once more.

Delta Airlines, in the interim, said Monday that it was working rapidly to address a “technical” issue making it hard for clients to purchase tickets.