Singapore Airlines Limited (SIA) is the flag carrier airline of Singapore. Singapore Airlines operates a hub at Changi Airport and has a strong presence in the Southeast Asia, East Asia, South Asia, and "Kangaroo Route" markets. Its wholly owned subsidiary, SilkAir, manages regional flights to secondary cities with smaller capacity requirements. SIA also engages the low-cost carrier sector through its stake in Tiger Airways and wholly owned subsidiary, Scoot. It ranks amongst the top 15 carriers worldwide in terms of revenue passenger kilometres, and 10th in the world for international passengers carried.