Thao and her holding company also own about a 20 percent stake in Ho Chi Minh City Development JS Commercial Bank or HDBank, according to the people. Thao’s the vice-chairman of the privately-held commercial bank, which has total assets of about $4.6 billion last year. The company has 225 branches and employs almost 10,000 people.

Thao’s foray into business began around 1988 as a second-year student in Moscow, where she was studying finance and economics. She began as a trade distributor with little money, receiving clothing, office equipment and consumer goods on credit from suppliers in Japan, Hong Kong and South Korea, and selling them in Russia in the years before collapse of the Soviet Union.

‘Being Honest’

"I worked so hard and earned the trust of suppliers by always being honest with them," said Thao, whose mother was a teacher and father, a pharmacist. "I didn’t have much money. They gave me more and more products with longer credit terms."

After making her first million three years later, Thao moved on to trade steel, machinery, fertilizer and other commodities.

She returned to Vietnam and invested in Techcombank, also known as Vietnam Technological and Commercial Joint-Stock Bank, and a second lender, Vietnam International Commercial Joint Stock Bank. She later lodged an application to run an airline in anticipation the communist government, which adopted a market economy in 1986, would open up the industry to compete against state carrier Vietnam Airlines.

‘Bikini Image’

VietJet is known for its young and attractive flight attendants who wear bikinis on inaugural flights to beach locations and featured similar models on its calendars, which Thao says are empowering images in Vietnam’s conservative culture.

"You have the right to wear anything you like, either the bikini or the traditional ao dai," she said, referring to the traditional long tunic worn over loose pants. "We don’t mind people associating the airline with the bikini image. If that makes people happy, then we are happy."

VietJet will probably surpass national carrier Vietnam Airlines as the nation’s biggest domestic carrier this year, according to CAPA Centre for Aviation. Vietnam is expected to rank among the world’s 10 fastest-growing aviation markets in the next two decades, according to the International Air Transport Association.