It’s not the second busiest by passenger numbers. All of the world’s busiest routes are in Asia.
It’s the second “highest earning” in terms of fare revenue, however.
It’s the second “highest earning” in terms of fare revenue, however.
It's somewhere around #5 by total number of passengers.
If you look at the real busiest routes (by passenger count), like Singapore to KL, they tend to use larger wide body aircraft which carry a lot more passengers per flight.