Congested Beijing is building fresh airport capacity that will see it become the world's largest aviation hub, leaving London - currently the world's busiest system of airports - and even ambitious Dubai in its wake. Beijing's new airport at Daxing south of the city could have up to nine runways and ultimate capacity to handle around 370,000 passengers per day, or a staggering 135 million passengers p/a. This would increase capacity at Beijing area airports to around 220 million p/a - almost a quarter of a billion passengers.