Despite the lowered projection, Boeing analysts predict that cargo planes will handle a significantly larger share of the freight market than they do today, though the expansion will come more at the expense of passenger planes than other sectors of the freight industry. Where all-cargo planes today carry 26% of air freight, in 20 years they will carry 30%.

According to Boeing, a shift toward larger freighters and more efficient airplanes such as its own DreamLifter will help keep air cargo transport affordable even as fuel prices climb. Boeing analysts expect the international air fleet to expand by more than 1,300 aircraft over the next 20 years, growing from 1,940 planes today to 3,250 by '28. By the end of the forecast period, the global cargo fleet will include 490 existing cargo planes, 710 new ones and 2,050 cargo planes converted from passenger aircraft. It will cost approximately $170 billion to build or convert new craft for the fleet.

Most of the 490 new factory-built planes will have substantially greater capacity than today's planes, with the ability to handle more than 80 metric tons of cargo. Boeing says there the market for new cargo planes with lesser capacity will be almost nonexistent because air freight will lose its place in the short-haul market as ground freight alternatives become quicker and more efficient.According to the report, global air freight declined 6% in '08 compared to '07 and has continued to fall at a comparable rate through the first half of this year.