WHEN she was training for her flying career, former stewardess Vanessa Khaw, 30, would often attract attention not because of her looks - she was in relatively uncharted territory as a female trainee pilot.

"All eyes are on you and they (male colleagues) are just waiting for you to make a mistake," said First Officer Khaw, who joined Tigerair as a pilot in 2010. She said: "You know you have to be just as good, or even better."

She is one of a small but growing number of female pilots with airlines here.

There are now 30 of them with Tigerair, Scoot, Jetstar Asia and SilkAir, nearly double the 16 at these airlines in 2010. There are no female pilots in Singapore Airlines.

Airlines say they do not discriminate by gender and that their hiring criteria for men and women are similar. To qualify, one must first graduate from flight school, which involves tests on memory, mathematics, psycho-motor skills and flying.

To rise up the ranks, one needs to chalk up thousands of flying hours. Pilots also have to pass annual tests to renew their licence. To be captain, one may have to log 5,000 hours flying a commercial jet, with 2,000 of these in command, as is the case at Scoot.

One veteran who has met the criteria and more is Captain Nilza Karmakar, 47, of Tigerair, who has flown 11,500 hours in her 17-year career. When she started nearly 20 years ago, female pilots were rare.

"There were so few female pilots, I didn't know if I could make it," said the Singapore permanent resident who earned her wings in Punjab, India.

These days, female pilots are becoming more common. As First Officer Khaw said: "As women see other women join the industry, they get the sense that it is possible... The stereotype of male pilots is slowly fading."

But challenges remain. Having a child usually means that a female pilot has to be "grounded" for about a year.

"You take some time to polish your skills in flying again, but it's okay," said Capt Karmakar, whose mother-in-law helped her bring up her daughter.

When she flew for Air India, she could spend up to five days away from home because of her flight schedule. But she can go home almost daily at Tigerair, she said.

She said she has not faced discrimination in the male-dominated industry.

"There is little a female pilot can't do. Modern aircraft are sophisticated... Hardly anything needs brute force," said Capt Karmakar, who flies an Airbus A-320. "To some extent, your male colleagues respect you for being one of the few females in the industry."

But First Officer Khaw and and Tigerair trainee pilot Natalie Ng, 25, feel they had to fight the equivalent stereotype of being a "female driver".

Said Ms Khaw: "The men may assume they can make it through flight school. But women put in the extra effort because they know they are the rare few. And you know what? They usually make it."