Many travelers using United Airlines faced delays Tuesday, but they weren't connected to Hurricane Isaac. Instead, the airline's computer network crashed, leaving large parts of its system paralyzed Tuesday afternoon.

First noted around 2:15 p.m. EDT, the problems persisted until about 6:30 p.m. EDT, when the airline tweeted that it is "in the process of resuming operations and rebooking customers."

The snarl of airline traffic led the Federal Aviation Administration to halt arrivals at airports in Newark, N.J.; Houston, and San Francisco. The order to stop those arrivals has now been lifted, according to The Florida News Journal.

News of the outage spread quickly via Twitter and other outlets. The FAA said that problems affecting United's airport computers seemed to be largely resolved by 5:30 p.m. EDT, but many passengers will see their travels disrupted well into Tuesday night — particularly with many Gulf Coast-area airports closed because of Hurricane Isaac.

United's main website was down for part of Tuesday afternoon. At 6:05 p.m. EDT, the airline tweeted, "The website is up, but not fully functional." The message also thanked passengers for their patience. Elsewhere on Twitter, passengers were reporting offers to book new flights at no added cost.

According to NPR's David Schaper, the problems stemmed from the airline's reservation and booking system. But because the same system also controls boarding passes, flight check-in and other functions, the outage had a widespread effect that left United passengers stranded at many airports.

In Denver, where the city's airport is one of United's main hubs, The Denver Post's Kristen Leigh Painter spoke to several people who had been stranded. One was Bruce Rehburg, a passenger who said he'd been sitting on a plane in Houston's airport for more than an hour and a half.

Copyright 2016 NPR. To see more, visit