Cleared for take-off. Airports with the highest average number of departures per month. A second factor ought to be more readily solvable. The military controls roughly three-quarters of airspace in China, and shunts civilian traffic aside. When the air force takes flight, commercial planes have no choice but to wait on the runway, sometimes for hours. The government has long vowed to do a better job of integrating civil and military management of airspace, and to release more air corridors for commercial use. Yet improvements have, so far at least, been imperceptible. It is a touchy subject. Airlines rarely inform passengers that military exercises are the reason for late departures, instead citing generic air-traffic controls or inclement weather, even on clear days. But official figures published in 2017 revealed that military activity was responsible for about a quarter of delays. It all adds up to more time stuck inside China’s gleaming (but frustrating) airports.