evidence: Three factors are putting more passengers in planes. "The first is the expansion of economies and the rise in incomes in Asia and Africa," says IATA’s David Oxley. [...] While growth in mature markets like Europe and North America will be more incremental, with existing passengers flying more, China, India, and Indonesia will see more first-time fliers. Either way, that translates into demand for new planes, as established markets upgrade aging fleets and emerging markets grow their flight networks. Boeing has pushed production on its 737 line, which now completes 42 aircraft per month, but is expected to release 57 per month by 2019.