Despite the air traffic congestion, demand is driving other airports in the region to add runways. Shenzhen completed its second last year and Hong Kong’s government has given in-principle approval for a third. “More runways do not necessarily provide more capacity if the airspace congestion issue cannot be resolved,” write researchers of the Aviation Policy and Research Center of the Chinese University of Hong Kong, calling for reforms. They estimate that congestion costs more than HK$1 billion (US$130 million) a year in fuel alone.

Jiang Huaiyu, director of the central and southern region of the Civil Aviation Administration of China (CAAC), told a conference of the region’s airports last year that Shenzhen’s second runway could support no major traffic growth because of congestion.

More optimistically, Law Cheung-Kwok, associate director of the aviation center at the Chinese University of Hong Kong, reckons that while the expansion of Guangzhou will surely demand further liberalization of the airspace, recent experience suggests that the air force will cooperate with the CAAC in opening up more access.

Further challenges loom, however. As authorities steadily remove restrictions, they must look toward a sixth airport in the region since the expansion at Baiyun could well be the last major upgrade for that facility.

Zhang Kejian, chairman of the facility’s listed operating company, last year said international experience suggests airports tend to become more efficient as they grow, but not past a capacity of 80 million passengers a year, or at most 100 million. Beyond that, it is better to build another airport, he says. That explains Guangzhou’s studies for another facility and Beijing’s decision to build another airport rather than further expand Capital Airport, China’s busiest.