Air passengers wait in check-in lines at Noi Bai Airport in Hanoi. Photo by VnExpress/Xuan Hoa

Some 6.7 million passengers flew between the two cities last year, making the route the seventh busiest, U.K. newspaper The Telegraph quoted OAG as saying.

Vietnam Airlines, Vietjet Air and Jetstar Pacific have been launching an increasing number of flights on the sector, and there are 45 daily flights now. The travel time is two hours and ten minutes.

The Jeju-Seoul Gimpo route topped the list with more than 13 million passengers, followed by Melbourne - Sydney, Sapporo - Tokyo Haneda, and Fukuoka - Tokyo Haneda.

In 2016, the OAG data had showed the Saigon-Hanoi route to be the seventh most crowded.

Vietnam’s aviation market is growing at the third fastest pace in the Asia-Pacific region, according to the aviation administration.

Vietnam had more than 94 million air passengers last year, a 16 percent increase from 2016.

The country’s biggest airports are Tan Son Nhat in Saigon and Noi Bai in Hanoi.