One of the worst travel days in years awaited fliers Thursday as airlines canceled more than 4,580 flights across the nation. And that already staggering total was expected to grow by day's end.
Overall, more than 10,000 flights have been canceled at U.S. airports just since Monday.
The source of the air-travel chaos: A massive winter storm that brought the world's busiest airport to its knees and snarled flights through the Southeast on Wednesday. By Thursday, the storm's bull's-eye shifted north, taking aim at a half-dozen of the nation's busiest airports along the populous I-95 corridor.
By late Wednesday evening, U.S. airlines had already preemptively canceled a massive number of Thursday flights, paring schedules at busy hubs from Washington north through Philadelphia and New York.
In Washington, both Reagan National and Dulles International airports had suspended all flight operations as of 6:45 a..m. ET, according to the authority that runs the airports. Reagan National is a hub for US Airways while Dulles is a busy hub for United.
At Baltimore/Washington International (BWI), airport officials warned fliers that "most airline flights cancelled this morning" and advised fliers to check on the status of their flights before trying to head to the airport. BWI is one of the busiest airports for Southwest Airlines.
In the New York City area, the Port Authority that operates Newark, LaGuardia and JFK airports said they "remain open, however there are many cancellations."
Elsewhere, flight schedules took a hit at just about every airport -- big and small -- throughout the Southeast and mid-Atlantic.
Flight-tracking service FlightAware counted hundreds of combined departure and arrival cancellations in the early hours of Thursday morning. More than 500 each at Atlanta, Philadelphia, Newark Liberty, Washington Reagan National, Charlotte and New York LaGuardia, according to FlightAware.
The Thursday tallies were smaller – but growing – at Washington Dulles and New York JFK.
Most big airlines waived change fees and relaxed rebooking rules for customers ticketed to fly through stormy airports, though the precise details varied by airline.
Thursday's air travel mess comes just a day after the winter storm responsible for the chaos grounded nearly the entire flight schedule at Atlanta's Hartsfield-Jackson International – the world's busiest airport.
Only about 300 of the normal 2,500 daily flights operated there, according to The Atlanta Journal-Constitution. That forced hometown Delta to ax nearly half of its nationwide flight schedule in a move that sent delays and cancellations to all corners of the nation. Atlanta's No. 2 airline – Southwest and subsidiary AirTran – canceled its entire flight schedule there Wednesday, saying it hoped to restart flights by early afternoon.
Wednesday also was a rough day in Charlotte – a major hub for US Airways – where more than 50% of the day's schedule was grounded.
Both Atlanta and Charlotte were having a mixed recovery, with more than 760 Thursday flights preemptively canceled in Atlanta and about 500 in Charlotte. That represented nearly a third of the entire day's schedule at each airport, according to FlightAware.
That would make Thursday the most brutal day for air travel in a week that's seen more than 10,000 canceled flights since Monday.
As of 7 a.m. ET Thursday, the weekly breakdown is as follows:
With so many affected passengers, it could take until next week before airlines are able to clear the backlog of fliers knocked off schedule by this round of disruptions.