Airlines are cancelling flights by the thousands and air travel has ground to a virtual standstill across much of the Northeast.
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Problems will continue through Saturday, thanks a potentially severe winter storm that's expected to bring blizzard conditions and snow that's measured in "feet" to large parts of New York and New England.
Nearly 5,000 flights have been canceled since Thursday in the United States, with most of those coming at airports affected by the storm.
Nearly all airlines had halted flights -- or planned to soon -- at airports in New York City and New England as of 4 p.m. ET. Officials from JetBlue, Delta and United tell Today in the Sky that at least some flights to the New York City airports could resume by early Saturday afternoon, though that depended on conditions at the airports following the storm.
JetBlue COO Rob Maruster says the airline is optimistic that it's New York-area flights could resume as early as noon Saturday.
Boston and New England flights, however, were likely to remain offline longer.
Maruster said JetBlue hoped JetBlue could resume flights to the region by 6 p.m., but cautioned it was too early to say with certainty. Other airlines echoed the sentiment that New England flights could be grounded longer because of the severity of the storm there.
As for the cancellations already tallied, more than half of the those were announced even before the first flakes fell in the Northeast. That highlights a trend in recent years in which airlines have proactively canceled flights ahead of a big storm instead of trying to operate right up until the worst conditions arrive.
United Airlines, the nation's biggest carrier, said on Thursday night that it had preemptively canceled 900 Friday flights in advance of the storm. Delta, the USA's No. 2 airline, put its total at 740. JetBlue, which has its two biggest hubs at New York JFK and Boston, said Thursday that it had already canceled 640 flights for Friday and Saturday.
Cumulatively, airlines so far Friday have axed about 3,200 flights and another 1,400 for Saturday, according to flight-tracking service FlightAware. That's on top of 370 canceled yesterday - again, mostly at airports that saw the first effects of the storm.
Already, the cancellation totals are piling up at many of those airports. Just at the three big New York City-area airports - Newark, LaGuardia and JFK - more than 1,800 combined flights have already been canceled today and another 690 for Saturday, according to FlightAware.
In Boston, the count stands at 510 today and 266 for Saturday. It's likely flights at Boston will be grounded altogether at some point during the storm, which would greatly inflate those numbers.
Southwest has already decided to suspend most flights at some airports, saying it would cancel the "majority" of its schedule today at Newark and LaGuardia. It's doing the same on Saturday for even more airports: Boston, Hartford, Long Island, Manchester and Providence.
With such a large number of cancellations, the flight disruptions in New York and the Northeast are all but certain to ripple through airports across the nation. A flight from Houston to Los Angeles, for example, could become delayed or canceled if the aircraft or crew scheduled to fly it gets knocked off schedule because of problems in Boston or New York.
Perhaps as evidence of that, FlightAware is reporting nearly 100 preemptive Friday and Saturday cancellations for Houston Bush Continental. At Miami, nearly 90 Friday and Saturday flights had been scrapped by Thursday evening. Both airports are hubs for airlines that also have hubs in the Northeast, meaning many of the cancellations in Houston and Miami are likely part of the ripple effect of the cancellations in Newark, JFK, Boston and elsewhere.
Against that ominous air-travel prognosis, airlines have relaxed rebooking rules and are encouraging customers to change their planes to avoid the storm's chaos.
Flexible rebooking rules
Delta was among the airlines to relax its rules, saying travelers scheduled to fly to nearly two dozen cities from Maine to Pennsylvania would be permitted to make a one-time change to their travel schedules without the standard fee.
"Delta is closely monitoring conditions along the storm's forecast path and encourages customers to consider moving up, postponing or re-routing their travel to avoid possible inconvenience from expected flight delays," the airline said in announcing its winter-weather policy.
Delta's waived-fee policy mirrors that of the other big airlines. American, Delta, United, US Airways and most other big carriers charge $150 or more for changing tickets - a fee that comes in addition to any difference in fare that might result.
Low-cost carrier Southwest - which flies more domestic passengers than any other U.S. carrier - does not charge a change fee, but said Wednesday that customers at several would be able to make a change with no recalculation of their fares.
JetBlue, one of the busiest airlines in the Northeast, is waiving fees at a dozen airports because of the storm. JetBlue operates its two biggest hubs at New York JFK and Boston, airports that are both in the storm's path.
The Associated Press contributed to this report.