Chinese aviation authorities will soon require captains of domestic flights into Beijing to master low-visibility landings to combat chronic flight delays that have been worsened by heavy smog.

Beijing Capital International Airport, China's busiest, has the worst record for flight delays of any major international airport, with only 18 percent of flights departing on time, according to travel industry monitor FlightStats. Thick smog has canceled or delayed flights at the Beijing airport when the city's visibility goes down to a few hundred meters — though officials typically blame the delays on weather conditions rather than pollution.

The new requirement will take effect Jan. 1, an official at the Civil Aviation Administration of China said Thursday. The official said the new skills would be required of all captains on Beijing-bound flights from China's other major airports, including those in Guangzhou, Shanghai, Chengdu and Shenzhen.

The captains will have to learn to land their aircraft with the assistance of precision auto-landing equipment when visibility falls to 400 meters. Currently, planes are diverted to other airports when visibility is that low.

Auto-landing allows a plane to land automatically with the supervision of a human crew. Experts say that the technology improves aviation safety, but that it requires additional pilot training to supervise the precision hardware both onboard and on the ground. The system is geared for three levels of visibility: 800 meters, 400 meters and zero visibility.

The new requirement will apply only to domestic flights because China doesn't have authority over foreign airlines' pilots.