- Newark, LaGuardia airports are most affected.
- American Airlines is suspending operations at all three New York-area airports.
- Airlines are waiving date-change fees for travelers affected by the storm.
Airlines have canceled more than 4,300 flights as an early spring nor'easter threatening to dump more than a foot of snow on the New York City area struck the region.
More than 70 percent of the departures from Newark Liberty International Airport, or 483 flights, were called off, according to flight-tracking site FlightAware. More than 430 departures, about three-quarters of those scheduled, were canceled from LaGuardia. A similar number of flights into those airports were also canceled.
Other affected airports include Philadelphia, all New York City-area airports, those in the Washington area and in Boston.
Carriers including American, Delta, United and JetBlue said travelers scheduled to fly on Tuesday or Wednesday from a dozen airports along the East Coast can change travel dates to as late as March 25 without paying a date-change fee. If travelers can only change their tickets beyond that date, they may have to pay a difference in fare.
Airplanes can generally fly in snow without a problem, but some flights can be called off in an effort to avoid accidents if visibility is low, winds are high or if runway conditions are unsafe. Airlines also cancel flights ahead of time to avoid stranding crews and passengers, which can lead to a cascade of delays later on.
American Airlines, the world's largest airline, said it canceled 1,450 flights throughout the Northeast, about a quarter of the airline's global Wednesday schedule, and that it is suspending its operations at LaGuardia and at John F. Kennedy International Airport until Thursday. That suspension includes its hourly shuttle service between LaGuardia and Boston, and LaGuardia and Washington. American also said it has suspended operations out of Newark until this evening.
"Since airlines likely based their proactive cancellations for today on the results from the past three weeks, it is possible that we won't see a sharp rise in further cancellations" from the current number, FlightAware said.
More than 10,000 flights were canceled this month because of back-to-back nor'easters, making it the worst March for cancellations in at least five years, FlightAware said.
Some 500 flights from, to or within the United States scheduled for Thursday were also cancelled including 108 flights from LaGuardia and 81 from Boston's Logan International Airport, according to FlightAware.