Although the air industry has been affected by the recent coro-navirus disease 2019 pandemic, it has shown rapid growth in eco-nomic development and evolving international trading worldwide. Such a trend is anticipated to resume post the pandemic, probably at a slightly slower pace. The growth of the air industry accelerated the movement of goods and people but also created challenges to air transportation systems, including operational inefficiency of airspace system, flight and passenger delays, divergent demands in aircraft manufacturing, and urgent needs for disruptive tech-nologies to enhance the existing air transportation system. Such challenges attracted the interests of researchers worldwide. This special issue assembles novel methodologies in air transportation, the cutting-edge findings, and outcomes of researchers' efforts responding to these challenges. It fills the gaps in existing litera-ture and offers solutions and directions on sustainable develop-ment of air transportation.