"My wife and I travel from Hanoi to the USA every year, but we are very excited this time as we enjoy business class seats at the price of an economy seat", he told VnExpress International.
The next day, another travel website The Points Guy reported seeing business class flights from Danang to NY selling for less than US$700 - "cheaper than a coach ticket".
Last year, British Airways sold tickets on routes to Dubai and Tel Aviv for as little as £167.
Other flights during the accidental dealweren't a whole lot more - with One Mile reporting a trip from Hanoi to NY for just $1,100 in business class and a first-class seat from Hanoi to Vancouver for $988.
SCMP added that several thousand flights between Vietnam and North America were believed to have been sold during the ticketing mistake, which was put down to human error.
"When I did the math, what I paid is at about a 95 percent discount", he said.
"The airline said that they'd make a decision on Wednesday about whether or not to honor these fares, and sure enough, they have".
Both carriers did not disclose how many people bought the cheaper tickets. The airline honored its mistakes and covered all bookings.
Last March, it posted a loss of £115m for the year to December.