1979 - Four brand new Airbus A300s were purchased to serve THAI's regional routes. Two Boeing 747-200 jumbo jets, with seating capacity of 371, were also purchased so that THAI could offer non-stop flights between Bangkok and Europe. The company moved into its 26-rai Head Office complex on Vibhavadi Rangsit Road, bringing all functions and departments together for the first time.

1980 - With the arrival of the jumbo jets, THAI was now ready for trans-Pacific services to North America. Los Angeles became THAI's gateway city into the US. At the same time THAI increased its operations to the Middle East.

1981 - THAI pioneered the North Pacific Bangkok-Seattle route. It expanded its routenet into the People's Republic of China by serving Canton. During that year, the company's share capital was increased to 1,100 million baht.

1982- To better manage its growth, THAI reassessed and consolidated its fleet and operations. Pool agreements on strategic routes were concluded with other airlines. Though the devaluation of the Thai baht affected revenues, THAI still posted a pre-tax profit of 26.3 million baht for fiscal year 1981/82.

1983 - THAI's Royal Executive Class was introduced on regional routes, setting a new standard in airline comfort and convenience. Business Class passengers enjoyed separate cabins, roomy armchair seating, lounges and privileged services. The airline broadened its focus into related industries and bought equity in Bangkok Aviation Fuel Services Limited (BAFS), Royal Orchid Hotel and the Airport Hotel.

1984 - THAI's efforts to promote provincial destinations inThailand intensified. Chiang Mai, already linked as an intermediate stop on Hong Kong flights, was serviced with daily turnaround flights from Bangkok. Phuket and Hat Yai were added as intermediate stops on the Singapore route. 

1985 - A new Maintenace Centre at Bangkok International Airport was built, enabling THAI to perform heavy maintenance on its wide-bodied aircraft in Bangkok. The facility was later expanded to a three-bay hangar able to accommodate two 747 jumbo jets and a narrow-bodied aircraft simultaneously. That year also saw the opening of THAI's (cargo Village), one of the largest cargo facilities in Southeast Asia at that time. Its 43,000 sq.m. terminal handled freight shipments for THAI flights and those of 28 other airlines.

1986  - THAI launched its Stockholm flight. The middle Eastern network was further expanded. The first branch of THAI's popular Airport Restaurant was opened at the new Chiang Mai International Airport Terminal.

1987 - New Domestic and International Passenger Terminals were built at Bangkok International Airport to cater for "Visit Thailand Year 1987." THAI provided 80 percent of all passengers handling services in the new terminals. The "Visit Thailand Year" campaign proved a huge success for the nation and the nation's flag carrier. Auckland and Madrid were added as new destinations.

1988 - THAI and its parent company, TAC, merged into a single airline, bringing together domestic and international air operations. With the addition of TAC's 11 aircraft, the combined fleet now consisted of 41 aircraft. The routenet comprised 48 cities in 35 countries around the world plus a network of 23 cities in Thailand.