HANOI - A power outage left the control tower at Vietnam's largest airport without radar for more than an hour on Thursday, according to state media reports, forcing many flights to reroute.
Dozens of planes could not take off or land at the Tan Son Nhat International Airport in southern Ho Chi Minh City between 0400 GMT (12pm Singapore time) and 0525 GMT.
"There was a power failure at the Tan Son Nhat airport air traffic control," leading to radar blackout, the state-run VNExpress website said.
"All flights expecting to land were told to reroute to other airports or return to their departing airports," the report said.
Aviation and transport officials in Vietnam were not immediately available for comment.
At least 33 flights by national flag carrier Vietnam Airlines and low-cost airline Jetstar Pacific were affected by the power failure, the report said.
Around 300 flights a day pass through Tan Son Nhat airport, which is already operating above its capacity.
Parliamentarians in the communist country are debating whether to approve the construction of a new multi-billion dollar airport near Ho Chi Minh City.
Although Vietnam's air safety record is reasonably good, a string of recent incidents have raised alarm among travellers in the nation.
Last month a Vietnam Airlines plane was reportedly about to take off from Tan Son Nhat airport when a military fighter jet turned sharply and cut into the path of the commercial jet.
In July, two planes nearly collided at an airport in central Vietnam after a young intern was left in charge of directing a busy runway.
And in June the crew of a VietJet Air plane carrying 200 passengers were suspended after a flight bound for the Central Highlands tourist hub of Da Lat landed at another airport more than 100km away.