Air cargo is an integral part of world business activity -- generating revenues of more than $45 billion annually while growing faster than passenger travel. As the undisputed air cargo market leader, Boeing offers a family of freighter models ranging from the 737 to the 747 -- offering an unmatched selection of revenue payloads, from 20 tons (18 tonnes) for the 737-700 Convertible to 124 tons (114 tonnes) for the 747-400 Freighter family.