In another sign of the strained economy, Hartsfield-Jackson International Airport predicts Thanksgiving travel crowds will be slightly smaller than last year. It’s the first forecast decline since 2001, when terrorist hijackings dampened demand.

Airport officials expect passenger volume at the world’s busiest airport to be down about 5 percent, reflecting cutbacks in airline schedules amid the weak economy.

“I would suspect you’ll have some people who will decide at the last minute to fly, so it may actually change a little bit,” airport general manager Ben DeCosta said Friday.

Many airlines have cut flight schedules by 10 percent or more, and while the reductions haven’t been as large in Atlanta, Delta and AirTran have trimmed Hartsfield-Jackson schedules. Airline flight capacity in Atlanta is down about 2 percent for the Thanksgiving period, according to the airport.

The airport’s early projections are for more than 1.5 million travelers to fly during the Thanksgiving travel period. The busiest days will be the Sunday after Thanksgiving, followed by the Monday after the holiday and the Wednesday before, said airport spokesman John Kennedy.

Specific daily numbers haven’t yet been forecast, but Kennedy said more than 250,000 people will use the airport on the busiest days.

Kennedy said Thanksgiving travel appears to be starting earlier, even at the end of this week.

Last year, officials projected a 4.6 percent rise in Thanksgiving holiday travel.

Still, a 5 percent decline will likely be imperceptible to peak-day fliers waiting in lines.

Hartsfield-Jackson in recent months has added additional security lanes which it expects to speed the process through the airport. The airport now has 32 security lanes across three security checkpoints.

DeCosta said he will be “surprised” if travelers encounter waits of more than 10 minutes.

But airport and airline officials still advise that travelers should allow extra time to get through the airport.

Atlanta-based Delta, the largest carrier at Hartsfield-Jackson and now the largest carrier in the world after its merger with Northwest Airlines, expects to serve about 1.8 million customers nationwide, roughly flat compared with last year. Delta encourages passengers to check in online before going to the airport to smooth the travel experience.

The Air Transport Association, an airline industry group, said it expects planes will average close to 90 percent full over the Thanksgiving travel period.

In addition to thinning holiday crowds, the weak economy has also jeopardized progress on the airport’s new international terminal.

DeCosta warned last week that the credit crunch was hurting efforts to sell bonds to finance the project.

“We’re still hoping to get in the market, but we don’t have any sense the market is selling yet,” DeCosta said Friday.