Deepening ties with China Southern is an alternative way in. American can’t increase services into China on its own planes, but a code-share agreement with a Chinese carrier would allow it to buy seats on a partner’s aircraft and offer “virtual” capacity instead.

This mooted investment doesn’t yet do that — but by investing in China Southern, American’s Chief Executive Officer Doug Parker raises the odds of getting the Guangzhou-based carrier to join it in the Oneworld grouping, which would open the door to the real prize of coordinating code-shares, frequent-flier programs and airport schedules.