Washington (CNN) -- If you're on your way to some of the nation's airports this holiday season and have a feeling there are fewer people schlepping their suitcases and looking for long-term parking spaces, it's not your imagination. The estimate for the upcoming winter holiday travel period predicts there will be fewer fliers than a year ago.





A projected 43.3 million air travelers will fly on U.S. carriers for both domestic and international routes during a 21-day period, according to Airlines for America (A4A), the industry trade organization for the leading U.S. airlines. That's a 1% drop from the same period last year which translates to about 20,000 fewer travelers on average per day.





However, travelers will not find that translates into more leg room once they board planes. On the busiest days, flights will be filled to at least 85% capacity, according to the forecast.





"Passengers still should expect to see full flights as many airlines have reduced capacity to match the decline in travel and increased cost of operations. Capacity reduction is one of the steps the industry is taking to preserve profitability," said A4A Chief Economist John Heimlich.





Lingering economic concerns, higher energy prices and less disposable income have all contributed to the slight decrease this winter, officials said.





The large weather system currently blasting parts of the West and Midwest is making driving through the southern Rockies dangerous but forecasters say to this point, it has not had a major impact on large airline hubs. However, forecasters are watching it closely.





"All hands are on deck and ready to go," said Tom Hendricks, A4A senior vice president for Safety, Security and Operations.





In the event winter weather causes problems, the FAA may open up Defense Department airspace not regularly available to commercial flights on an as-needed basis to help ease congestion.





Daily passenger volumes are expected to range from 1.6 million to 2.3 million during the holiday.





The busiest days are expected to be between December 21 through December 23, December 26 through December 30 and then January 2 and 3 as travelers fly home.





The airline organization recommends passengers check airline websites before they leave for the airport, pack gifts unwrapped to lessen security delays and review carry-on rules for liquids, gels and aerosols.
On the busiest days, flights will be filled to at least what capacity? What percentage of a drop is that from the same period last year? How many air travellers will fly on U.S. carriers? To what capacity are the flights filled on busy days? What percentage reduction is there in U.S carrier air travellers? A projected 43.3 million air travelers will fly on what?
85% 1% 43.3 million 85% 1% U.S. carriers
question: On the busiest days, flights will be filled to at least what capacity?, answer: 85% | question: What percentage of a drop is that from the same period last year?, answer: 1% | question: How many air travellers will fly on U.S. carriers?, answer: 43.3 million | question: To what capacity are the flights filled on busy days?, answer: 85% | question: What percentage reduction is there in U.S carrier air travellers?, answer: 1% | question: A projected 43.3 million air travelers will fly on what?, answer: U.S. carriers