IATA's latest figures have underlined the crisis in the cargo market, showing a 22.6% drop in international freight traffic during December.
The fall meant that international cargo traffic over the whole of 2008 fell by 4%.
IATA describes the figures as "unprecedented", and director general Giovanni Bisignani says: "There is no clearer description of the slowdown in world trade."
The collapse in freight business reflects 20-30% falls in export and import volumes being reported across Asia, North America and Europe, says IATA.
"This year is shaping up to be one of the toughest ever for international aviation," says Bisignani, adding that the dismal cargo figures "put us in uncharted territory, and the bottom is nowhere in sight".
Passenger traffic was up by 1.6% during the year, although it declined by 4.6% in Decemeber - a fall partly stemmed by year-end leisure travel.
Airlines cut capacity by 1.5% in December, but could not keep up with the drop in demand. Passenger load factor was down 2.4 points to 73.8%.
Asia-Pacific carriers experienced the sharpest international passenger traffic fall during the month, down by 9.7%, while the figures for North America and Europe were down by 4.3% and 2.7% respectively.