The impact to airlines from airspace closure can be as benign as a two minute extension on an arrival pattern, or as catastrophic as a shoot down from a surface-to-air missile, as the tragic loss of Malaysia Airlines Flight 17 over the Ukraine in July 2014 demonstrates. Airspace constraints come in a variety of forms, both man-made and physical, but all result in operational inefficiencies that erode the economic vitality of an airline. Understanding the root causes of these airspace restrictions, developing strategies for mitigating their impact, and anticipating future airspace closures,...