Passenger traffic dropped 4.6 percent compared with 2007, the IATA said, USA Today reported Friday.
For the year, 74 percent of the available seats were sold, while cargo shipping fell 22.6 percent.
"There is no clearer description of the slowdown in world trade," IATA Chief Executive Officer Giovanni Bisignani said.
IATA represents 230 airlines worldwide.
Year end reports indicate the only large U.S. airline to post a profit in 2008 was Southwest Airlines. JetBlue, US Airways, Continental, American, Delta and United all had losses for the year, much of it related to fuel costs which spiked in mid-summer.
"Like other airlines that have reported before us, our financial results reflect the staggering increase in fuel prices we faced throughout most of 2008," said US Airways CEO Doug Parker.