Only nine out of 19 permitted flights took off on Tuesday while an equal number were canceled as they had few or no passengers.
The other failed to leave due to quarantine regulations, according to the Civil Aviation Authority of Vietnam (CAAV).
Those that were canceled due to lack of passengers were from HCMC to Da Nang, Phu Yen, Hai Phong, Rach Gia, and Ca Mau; Da Nang to Can Tho and Dak Lak; Hanoi to Da Nang; and Thanh Hoa to Lam Dong.
The HCMC-Gia Lai flight operated by Vietjet Air was also canceled for a second consecutive day as authorities in the Central Highlands province required arrivals from HCMC to undergo seven-day quarantine.
Hanoi, Hai Phong and Thua Thien-Hue too had such requirements before they scrapped them and allowed passengers from HCMC to monitor their health at home for seven days.
A spokesperson for a carrier said the travel demand to HCMC remains low, forcing cancelation of flights to avoid losses.
Besides, airlines are only allowed to sell 50 percent of their seats due to social distancing requirements, leading to an increase in fares.
The CAAV wants the Ministry of Transport to remove the requirement after the trial program ends on October 20.
The ministry requires all passengers to be fully immunized at least 14 days before travel or have recovered from Covid-19 within the previous six months.
They should also furnish Covid negative results obtained within 72 hours of departure.