The industry trade organization Airlines for America forecasts that 51 million passengers are expected to fly globally on US airlines over the 21-day winter holiday travel period from December 15, 2017, until January 4, 2018, which indicates a 3.5% increase over the 49.3 million travellers estimated to have flown over the same period in 2016-2017.

A4A expects the busiest travel days to be December 21, December 22 and December 26, while the lightest travel days are expected to be December 16, Christmas Eve, Christmas Day and New Year's Eve. Passenger volumes are expected to vary. On the lightest days, the number of US airlines' passengers will be just below 2 million, according to the forecast, while more than 2.7 million people will fly on the busiest days. Thus, the airlines will have to add flights and utilize larger planes, as they will need to offer 91,000 additional seats per day across their networks to accommodate the 80,000 additional daily passengers expected to travel over the holidays.

“US airlines boosted staffing levels for 47 consecutive months and are expected to do so throughout the holiday period to accommodate the millions of holiday travelers,” the trade organization stated.

An improving economy and sub-inflation airfares are among the main reasons of expected passenger traffic growth, A4A said.

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