United Airlines plans to add daily flights to Vietnam and Thailand in October, further expanding the network for the U.S. carrier that already has the most Asia service. In the expansion, United is using a tactic that’s unusual in its network: Its airplanes from Los Angeles and San Francisco that are headed for Hong Kong will then go on to the two new destinations. The Bangkok and Ho Chi Minh City, Vietnam, service is set to begin on Oct. 26. On Oct. 25, United plans to add a second daily nonstop flight from San Francisco to Manila, Philippines, and on Dec. 11, it will launch nonstops from San Francisco to Adelaide, Australia, which will operate three days a week. The carrier has aggressively been adding far-flung destinations not served by rivals to its routes, like Nuuk, Greenland, and Bilbao, Spain, which start later this year. Getting the mix right is especially important as carriers…
