Airlines are airborne once more. Recapitalised by rich parents and governments, or hammered together in mergers, carriers are surveying a competitive landscape stripped of most marginal operators. Half of the world’s top 30 airlines by market capitalisation are poised to make at least a double-digit return on equity this year.

Yet this is an industry that has consistently vaporised more shareholders’ funds than almost any other. Even in China, where total air traffic grew by almost a third in the year to June, airlines can take nothing for granted. Take Air China, the flag carrier. Highlights from this week’s interim figures seem great: passengers carried up more than a third to 26m, 13 new domestic routes opened, and a merger with Shenzhen Airlines gives Air China a third hub to add to Beijing and Chengdu.

Yet this is not as good as it was supposed to be. Three years ago, Li Jiaxiang, the former chairman, outlined a vision of turning Air China into an “international supercarrier”. But despite having all the might of the state behind it (Mr Li now heads the industry regulator, the CAAC), the airline has struggled for traction. While domestic passengers have almost exactly doubled since its interims in 2007, international passengers have shrunk from 3.5m to 3.1m. Back then, international revenues were 41 per cent of the whole; they’re now 35 per cent, driven mostly by cargo. Expansion plans were put on hold by a bitter domestic price war. Air China’s revenue per passenger has fallen from Rmb1,306 ($192) in 2007 to Rmb1,089 now.