Santa Claus won't be the only one to take to the skies this holiday season.

Some 51 million people will fly globally on U.S. passenger airlines during the 21-day holiday period, which runs from Dec. 15 to Jan. 4, according to Airlines for America. The figure represents a 3.5 percent increase from the same period in 2016.

"With affordable fares and expanded route options, flying to see family, friends and loved ones this holiday season is more accessible than ever before," A4A Vice President and Chief Economist John Heimlich said. "Intense competition within the airline industry is enabling passengers to choose the flights that most closely match their preferences and budgets."

A4A expects the busiest travel days of the 21-day period to be Dec. 21, Dec. 22 and Dec. 26, while the lightest travel days will be Dec. 16, Christmas Eve, Christmas Day and New Year's Eve. Passenger volumes are expected to vary widely, ranging from less than 2 million on the lightest days to more than 2.7 million on the busiest.

At the same time, AAA forecast that 2017 could be a record-breaking year for holiday travel.

More than 107 million Americans will take to planes, trains, automobiles and other modes of transportation during the holiday period from Dec. 23 through Jan. 1, according to AAA. More than 97 million travels will drive for at least part of their trip.

"More expensive gas prices are not swaying holiday revelers to stay home," said Bill Sutherland, AAA senior vice president, Travel and Publishing. "In fact, across the board this year, travel has increased year-over-year for every major holiday weekend—Memorial Day, Independence Day, Thanksgiving—and we project the same for the year-end holiday period."

CEO Dateline will resume on Tuesday, Jan. 2.

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