Fewer people are expected to travel by air over this Thanksgiving holiday, as Americans worry about airport and airplane security.

Industry experts expect air travel to be down at least 15 percent from a year ago, due largely to the weak economy and travelers' fears after the September 11 terrorist attacks and the deadly crash last week of an American Airlines jet in New York.

The American Automobile Associations estimated that 34.6 million Americans will travel at least 50 miles from home during the Thanksgiving holiday, a 6 percent decline from last year.

A record 87 percent are expected to drive, while the number taking airplanes, trains and buses is expected to drop 27 percent due to a decline in air travel, the AAA said.

Greyhound Bus Lines reported a 20 percent surge in advance-purchase tickets for the Thanksgiving period and an increase in trips longer than 1,000 miles.

Amtrak is getting 10 percent more inquiries about tickets than it did one year ago, when the passenger rail service carried 567,000 people.

The Air Transport Association, which represents the major U.S. carriers, said air travel probably would decline 15 percent to 20 percent from last year.