Vietnam-based low-cost carrier (LCC) Vietjet Air reported a 2015 revenue of VND10.9 trillion ($490.7 million), up 34.5% from VND8.1 trillion in 2014. The airline said the revenue increase was achieved “despite increasing challenges in the wake of the ASEAN Open Skies policy.”

The result was lower than the VND13.8 trillion forecast at the start of 2015, and came during a year when the carrier added 11 Airbus A320s and A321s to its fleet and increased passenger numbers by 66% to 9.3 million passengers during the 12-month period, compared to 2014.

“The company met its targets,” Vietjet said in a statement, adding that it saw an average 88% load factor, with an on-time performance (OTP) ratio of 82.58% for the 58,355 flights it made during the period.

The company has expanded rapidly and has offered passengers a series of offer flights, including up to 400,000 low- or zero-cost tickets on international routes to Seoul, Taipei, Singapore, Bangkok and Yangon.

Its expansion comes after Vietnamese Deputy Prime Minister Hoang Trung Hai urged local airlines to “overcome shortcomings and limitations,” reduce airfares, improve service quality, and expand domestic and international routes.

Vietjet has set a target of 15 million passengers in 2016, with an OTP ratio of 85%.

As of Dec. 31, 2015, Vietjet operates 28 domestic and 12 international routes using a 30-strong fleet of Airbus A320s and A321s.