Domestic air service was furnished by Thai Airways Company (TAC), a government-owned entity established in 1951. There were some 130 airfields of all categories throughout the provinces, 104 of which were in usable condition, in addition to the major airport at Bangkok. In the early 1980s, service was provided to about twenty airports. In addition to domestic service, TAC also flew to Penang in Malaysia, Vientiane in Laos, and Hanoi in Vietnam. The principal Thai-flag international service was provided by Thai Airways International (THAI), founded in 1959 by TAC jointly with the Scandinavian Airlines System (SAS); TAC held 70 percent of the shares and SAS 30 percent. THAI’s routes included flights to Asia, the Middle East, Europe, North America, and Australia. Approximately thirty international airlines flew into Thailand. Both TAC and THAI had greatly expanded and upgraded their fleets by the mid-1980s. In 1985 THAI placed orders with the European aircraft manufacturing consortium Airbus Industrie for four A300-600 medium-range jumbo jets, making the airline the third largest Airbus user in the world, with sixteen airplanes. Also in 1985, THAI ordered two more Boeing 747s, making a total of eight, for use on its long-distance routes to Europe, North America, and Australia. In 1987 Prime Minister Prem Tinsulanonda approved the proposed merger of THAI and TAC, which was expected to be carried out by 1989.
The principal international airport was Don Muang outside Bangkok. The airport had long been Southeast Asia’s main air traffic center for flights between Asia and Europe (although at the beginning of the 1980s it was experiencing strong competition from Singapore). The airport was used jointly by civilian airlines and the Royal Thai Air Force, resulting in growing congestion as international flights increased. During the mid-1970s, consideration was given to building a new civilian airport, but in 1978 a decision was made to move some military operations to other airports. A two-year expansion program for Don Muang was then initiated, and a new state enterprise, the Airport Authority of Thailand (AAT), was legislated and took over administration of the airport in July 1979. In 1979 the airport at Chiang Mai was upgraded to become an international airport. In 1985 THAI opened a new cargo terminal at Don Muang International Airport as part of its plan to expand its cargo business. That same year a new wide-body aircraft maintenance center was inaugurated at Don Muang as a bid to make Bangkok a regional service center for Airbus and Boeing planes.