Boeing projects air cargo traffic will grow at an annual rate of 4.7 per cent over the next 20 years, with global air freight traffic expected to more than double by 2033. The company released its biennial World Air Cargo Forecast at the International Air Cargo Forum and Exhibition earlier. “We see strong signs of a recovery as air freight traffic levels continue to strengthen after several years of stagnation,” said Randy Tinseth, vice president of marketing, Boeing Commercial Airplanes.