Duong Tri Thanh, Vietnam Airlines CEO, told a forum Wednesday continued delays at Tan Son Nhat could drag down flight quality and hamper economic growth.

The route itself ranked as sixth busiest domestic route in the world for 2019, up one spot from last year. Le Hong Ha, deputy general director of the flag carrier, said Tan Son Nhat has recorded low punctuality due to overload, with airlines forced to adjust flight times that cause take-off delays up to 15 minutes.

Lai Xuan Thanh, chairman of the Airports Corporation of Vietnam, said this year, foreign airlines have struggled to find berths at Tan Son Nhat.

The airport could only provide 2-3 percent more slots this year, meaning passenger growth is capped at 5 percent year-on-year, he added.

However, the country is allowing operation of new airlines despite the overload. Private carrier Bamboo Airways launched its first flights earlier this year, while three more airlines are awaiting licensing.

Dinh Viet Thang, head of the Civil Aviation Authority of Vietnam (CAAV), said Vietnam still holds great aviation potential, with an estimated 150-180 million air passengers predicted by 2025.

Only five airlines operate daily routes in Vietnam, with the figure in Thailand at 16, Indonesia at 12, Philippines at 10 and Singapore at 6.

Vietnam plans to upgrade existing and build new airports to accommodate surging travel demand, a third terminal proposed for Tan Son Nhat to up capacity by 20 million passengers a year.