Flying from Noi Bai International Airport to Phu Quoc Island off the southern coast last Saturday, Quynh Nhu said her flight was meant to take off at 3:15 p.m.

Nhu and other passengers boarded the plane as scheduled, but it only departed one hour later at 4:15 p.m.

"We arrived two hours before departure as per flight regulations, but still could not fly on time. Waiting on the plane is much more stressful and tiring than in the terminal," Nhu said.

Five other planes were also queued up behind theirs waiting to leave.

Both Noi Bai International Airport and Tan Son Nhat International Airport had shut down one runway each starting this month as part of a major runway and taxiway upgrade overseen by the Ministry of Transport.

With Vietnam enjoying summer, a peak travel period, airlines have urged customers to show up at check-in counters much earlier than usual to avoid overload and delays.

According to carriers, schedules started lagging as soon as the two runways were shut down.

A representative from Vietnam Airlines said many of its flights have been delayed at both Noi Bai and Tan Son Nhat, impacting operations at other airports.

The on-time performance rating for Vietnam Airlines generally hits over 90 percent, but for the past week it has dropped to between 56-88 percent.

Bamboo Airways said it has adjusted departure times for tens of flights a day due to the runway closure and canceled several along its HCMC-Da Nang and HCMC-Phu Quoc routes.

Vietjet Air, in turn, stated its planes too had to queue up for departure since the runway upgrade commenced during a peak travel time.

The airline suggested both airports shorten the distance between every two planes about to land from five to three miles. This would allow each to touch down faster and as a result, shortening the waiting time for those that need to use the runway for takeoff, it said.

To Tu Ha, deputy director of Noi Bai, said the airport used to have two runways for takeoff and landing but now, only one is operational.

The airport has reduced the number of flights taking off and landing in one hour from 36 to 27 but still could not avoid a pile up, especially during daytime from 8 a.m. to 5 p.m.

The Civil Aviation Administration of Vietnam has requested Vietnam Air Traffic Management Corporation to work with flight control units at both Noi Bai and Tan Son Nhat to shorten the distance between landing planes to three miles to reduce the waiting time for all others.

In case there are planes already waiting on the runway, flight control units must not let more move onto the runway, it stressed.

In a public letter issued Tuesday, Transport Minister Nguyen Van The said runways and taxiways in the two airports will be shut down one after another so the entire upgrade project could complete before the Lunar New Year 2022 holiday, which is in February.

The minister said "work will affect the operations of all carriers and create inconvenience for passengers, but it is hoped everyone would understand the situation."

Since 2017, Noi Bai and Tan Son Nhat airports have been chronically overloaded, receiving new-generation aircraft with huge loads, which has degraded their runways and taxiways.