( CNN ) -- How do the world 's busiest airports rate when it comes to getting planes off the ground on time ? We 've taken the top 20 airports in terms of total passenger numbers and ranked them according to how often flights take-off with 15 minutes of the scheduled departure time . The figure for each airport is the percentage of flights that depart on time . Tokyo 's Haneda tops the list with on average 9 out 10 flights departing on time , but do n't expect to leave China 's main airports on time -- they prop up the list with only 1 out of 4 flights hitting their allotted take-off slot . Read more : How airports cope with bad weather . Statistics courtesy of Flight Stats taken from airport information for 2012 .
Tokyo Airport is the best for on - time departures . Despite a patchy reputation , Atlanta comes in second . airports in China have the worst reputation for timely take - offs .