Question: What low-cost airline headquartered in Tan Binh District, Ho Chi Minh City, Vietnam, has the second busiest airport in Vietnam with its hub?
Sentence (from "Noi Bai International Airport"): Nội Bài International Airport (IATA: HAN, ICAO: VVNB) (Vietnamese: "Sân bay Quốc tế Nội Bài" ) in Hanoi, the capital of Vietnam, is the largest airport in Vietnam in terms of total capacity.
Relevant evidence: No