NEW YORK -- Hurricane Sandy was already impacting Seattle on Sunday, frustrating hundreds of passengers at Sea-Tac airport.
Many Sea-Tac travelers spent the day back and forth between departure boards and counter lines. Flights to New York, Philadelphia, and Washington D.C. - places where Sandy is expected to do the most damage - are grounded until at least Tuesday.
The massive storm threatens to bring a near halt to air travel for two days in a key region for both domestic and international flights.
On Sunday, the airlines moved planes away from the East Coast to avoid damage, and added flights out of Washington, D.C., and New York City area airports.
Cancellations are starting to mount. According to the flight-tracking service FlightAware, 1,200 Sunday flights have been canceled as of mid-afternoon. Approximately two-thirds of those were flights into East Coast airports. At Newark International Airport, a hub for United Airlines, there were nearly 300 total cancellations.
[Check Sea-Tac travel advisories]
For Monday, when Sandy is expected to make landfall, nearly 4,600 flights have already been canceled, about 2,300 of those at Newark, and New York's Kennedy and LaGuardia airports. Another 650 have been scrapped at Philadelphia International, according to FlightAware.
Another 640 flights have been canceled for Tuesday, and FlightAware expects that number to grow.
A spokesman for United Airlines parent United Continental Holdings Inc. said the carrier has suspended an unspecified number of flights to New York and Washington-area airports beginning Sunday evening with plans to resume Tuesday as conditions permit.
JetBlue Airways Corp., which flies out of JFK, said it has canceled more than 1,000 flights from Sunday through Wednesday morning.
American Airlines and American Eagle canceled 140 flights Sunday and canceled another 1,431 flights Monday through Wednesday due to Hurricane Sandy, the company said.
US Airways said it had suspended all operations at the three New York airports Sunday evening and Monday and at Philadelphia and Washington on Monday.
The disruptions also impact international carriers. Air France has canceled four Monday flights into JFK and two departures. Lufthansa canceled three flights to the Northeast and one flight out of Newark.
Hurricane Sandy is heading north from the Caribbean, where it has left nearly five dozen dead, to meet a winter storm and a cold front, plus high tides from a full moon. Experts say the rare hybrid storm that results will cause havoc over 800 miles from the East Coast to the Great Lakes.