Boeing has cut its freighter demand forecast for the next 20 years, citing a "sluggish" cargo market.
Its latest Commercial Market Outlook predicts a global fleet of 3,200 freighters by 2031 - down from last year's figure of 3,500.
This is nevertheless a near-doubling of the current fleet of 1,740 cargo aircraft.
There will be demand for 940 new-build freighters and 1,820 converted aircraft, says the forecast.
Large freighters - with more than 80t capacity - will account for 680 of the new-build airframes. The other 260 will be in the medium-capacity category of 40-80t.
Speaking at a briefing in London, Boeing vice-president for marketing Randy Tinseth said there was no demand for new-build freighters with capacity below 45t.
But he says there will be 1,120 conversions in this category. "The conversion market is especially important when we look at the smaller segment," Tinseth states.