Boeing has cut back its 20-year forecast for freighter demand to reflect the downturn in 2001, but has again predicted sustained growth for the widebody fleet which is expected to account for 60% of the 3,078 cargo aircraft forecast to be in service by 2021. Although overall numbers are down - 13% from the 3,520 figure originally forecast for the 20-year period - Boeing says the overall world freighter fleet will still grow 75% over the next 20 years. A total of 2,531 aircraft are expected to enter the fleet by 2020 - 681 new build freighters and 1,850 conversions - while 1,228 will be retired. Boeing believes that the biggest drop will be in modified or converted aircraft, where around 400 fewer conversions are now forecast.