Hurricane Sandy grounds flights in Boston, NYC, Washington DC

Hurricane Sandy grounded thousands of flights in the U.S. northeast Monday and upended travel plans across the globe, stranding passengers from Hong Kong to Europe. The massive storm threatens to bring a near halt to air travel for at least two days in a key region for both domestic and international flights.

Major carriers such as American Airlines, JetBlue and Delta planned to cancel all flights into and out of three area airports in New York, the nation's busiest airspace. According to the flight-tracking service FlightAware, nearly 7,500 flights had been canceled for Sunday and Monday. Both Philadelphia International Airport and Newark International Airport, a hub for United Airlines, each had more than 1,200 cancellations for the two days.

Delays rippled across the U.S., affecting travelers in cities such as San Francisco to Chicago, and disruptions spread to Europe and Asia, where airlines canceled or delayed flights to New York and Washington from cities that are major travel hubs including London, Paris, Tokyo and Hong Kong.

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Travelers such as businessman Alan Shrem, who was trying to return home to Boca Raton, Florida after attending trade fairs in Hong Kong and China's Guangzhou, were facing long waits for a new flight.

Shrem said he was "edgy" and "exasperated" after learning his Monday morning Cathay Pacific flight to JFK was canceled.

He learned he could be stuck in Hong Kong for nearly a week because the next available seat was Nov. 4. Cathay ticketing counter staff at the airport put him on a waiting list for seats that could become available earlier, but he didn't hold out much hope.

"I don't know what number I am, I could be 300. They don't even tell you. They just say: Yeah, it's a pretty big waiting list," said Shrem, throwing up his hands.

Shrem, whose company produces signed sports memorabilia, was one of a handful of travelers trying to rebook their flights at Hong Kong's airport. Cathay urged people whose flights had been canceled not to come to the airport. In the meantime, he'll have to fork out $400 a night to continue staying at a nearby hotel. The airline won't pay for accommodation for stranded passengers if delays are weather related.

"It's insane. It's crazy. It's going to wind up costing me thousands and thousands of dollars by being stranded here because of the weather," Shrem said.

Sandy, a Category 1 hurricane with sustained winds of 75 mph (120 kph) as of early Monday, was blamed for 65 deaths in the Caribbean before it began churning up the Eastern Seaboard. Forecasters say the hurricane is about 425 miles (685 kilometers) southeast of New York City and the center of the storm is expected to be near the mid-Atlantic coast on Monday night, colliding with a wintry storm moving in from the west and cold air streaming down from the Arctic. Experts say the rare hybrid storm that results will cause havoc over 800 miles from the East Coast to the Great Lakes.

At New York's LaGuardia on Sunday, crowds filled the American Airlines terminal near midday, with families sitting on the floor waiting for a flight out — any flight out. A few travelers were sitting at a bar having a beer, watching football. Others nervously paced before flight information boards showing canceled flights, hoping their flight wouldn't be added to that list. It was almost double the normal crowd. Travelers were calm, but anxious.

The Port Authority of New York and New Jersey, which runs five airports in the area, said it expects all carriers to cease operations Sunday night. It advised passengers to check with their carriers before heading to the airport.

Passengers on Sunday were reporting multi-hour wait times at airline call centers.

Eileen Merberg, 50, was booked on a United flight from her home in Rochester, N.Y. to New Orleans, connecting at Washington D.C.'s Dulles airport.

First, the airline sent her an automated message via email saying that her Washington flight was canceled and that she had been rebooked on a flight through Newark. About an hour later that flight was canceled. Another email informed her she was rebooked through Chicago.

By that point, she already had told the higher education conference that she was scheduled to speak at that she wouldn't be coming. She tried to cancel her flight but United's phone lines were jammed. First she waited 62 minutes before her phone battery died. After recharging, she then spent 45 minutes on hold before a recording told her it would be at least another hour before a customer service employee would be available.

"Then I hung up," Merberg said.

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.

Disruptions on the East Coast of the U.S. also impact international carriers. All flights from Paris to Boston, New York, Philadelphia and Washington — a total of 14 — were canceled. Air France has canceled four into JFK and two departures.

Frankfurt airport canceled 12 flights, with German carrier Lufthansa scrapping three to the Northeast and one out of Newark. British Airways had to cancel all its flights to and from New York, Newark, Baltimore, Washington DC, Boston and Philadelphia — a total of 20.

Eight flights out of Tokyo's Narita International Airport to New York, Newark and Washington were canceled Monday.

Hong Kong's Cathay canceled its two daily flights to New York for Monday and Tuesday and Air India said its daily flights to Newark and JFK had halted since Sunday.

South Korean flag carrier Korean Air delayed a flight scheduled to leave Incheon International Airport for JFK on Monday by 22 hours. Asiana Airlines delayed its JFK flight from Seoul by 26 hours.

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Kelvin Chan in Hong Kong, Lori Hinnant in Paris, Danica Kirka in London and David Rising in Berlin contributed to this report.

Copyright 2012 The Associated Press.