And China and India are booming. The largest airplane order was from Indica, a domestic airline from India. 410 orders for Airbus 320. Airbus with their government funding is able to give them very long lease terms and guaranteed buy back price. Boeing needs to raise cash on commercial paper, Airbus does so on government underwritten bonds. But that is a different story.
Confluence of these factors, and a general belief that oil is never going to exceed 100$ ever again is fueling the optimism and large airplane orders. Oil producers trying to kick their oil dependence are trying to become transportation centers. Now a days it is impossible to beat the fares offered by Emirates, Qatar, Kuwait, Etihad to India/China from USA. So even the oil states are investing in airplanes.
They believe the moment oil goes above 60, fracking becomes profitable again. At 80, the fracking will flood the market with over supply and oil will slideback.