WASHINGTON (AP) -- Some European airports reopened Tuesday, but others are still closed and airlines still can't tell when flight schedules will return to normal. Scientists are concerned that an eruption of the Icelandic volcano Eyjafjallajokull, that has grounded planes since last Thursday, will trigger an even bigger eruption of a nearby volcano, Katla. Katla last erupted in 1918, and historically the two volcanos have erupted together.
About 80 flights between the U.S. and Europe were canceled, Thursday as dozens of European airports closed due to clouds of ash from the eruption. Since then about 95,000 flights have been cancelled.
Most of the canceled U.S. flights were to and from Britain, said David Castelveter, a spokesman for the Air Transportation Association, which represents most major U.S. carriers. Some airlines were also canceling flights scheduled for Friday, he said.
Federal Aviation Administration spokeswoman Laura Brown said the agency was working with airlines to reroute flights from the U.S. to Europe around the cloud where possible. Some flights were also returned to the U.S. last night.
Airports in Britain, Ireland and Nordic countries have been closed because ash from the volcano that erupted Wednesday makes flying too dangerous. France said it was closing 23 airports, including Paris airports.
But flights to other destinations are also affected. Brown said the route for most flights from the East Coast to Europe crosses the North Atlantic near the ash cloud. Brown said the FAA and airlines are working to reroute some flights.
A spokesman for the Port Authority of New York and New Jersey, which operates New York's three metro area airports, would not comment on flights and the impact of the air space closure on individual airlines.
The route between New York and London is the second busiest in the world, behind the route between Hong Kong and Taiwan.
Tyrone Lowery, the front desk supervisor at the 360-room International JFK Airport Hotel in New York, said over 150 guests had been affected by the flight cancellations.
"So far they're taking it," he said. "Some of them are disappointed."
He said most had booked one-night stays.
British Airways spokesman John Lampl said the airline had several flights out of the U.S. bound for Heathrow that were returned to their departure cities or forced to land elsewhere when London airports were closed. That includes flights from Chicago, San Francisco, Denver, Las Vegas and New York. Some passengers were being put up in hotels.
Some flights made it out of the U.S. late last night, but more were being canceled Thursday morning.
"This will domino into every airline," Lampl said. "Everybody's in the same boat."
American Airlines canceled 21 flights that were scheduled to arrive at or depart from London after U.K. authorities closed the airspace, said airline spokesman Tim Smith. He said American was able to make six takeoffs and nine arrivals at Heathrow before the shutdown.
Smith said American flights to other points in Europe were not affected as of Thursday morning, Central time. He said passengers on the canceled U.K. flights were booked on later trips or given a refund.
At the British Airways Terminal at John F. Kennedy International Airport, William Phelps and family told a local radio station that they had decided to stay longer in New York after their flight to London's Heathrow Airport was canceled.
"It's the simplest thing for us," he said. As for his children, he said they were fine with the change in plans. "They love New York, so that's OK."
Volcanic eruptions rarely interrupt commercial air travel, but some large ash clouds high in the atmosphere have the potential to stall or shut down jet engines.