AS each Air India A310 Airbus climbs out of Kai Tak on its way to Delhi and Bombay, chances are that it will be carrying a cargo of clothes for Mother Teresa. The clothes, shoes and other small items are gathered by members of the Indian community in Hong Kong and flown free of charge by the airline to help Mother Teresa's charitable operations in Calcutta. ''Hong Kong is very affluent, and when we were approached and asked to carry the clothing, we were pleased to be able to help,'' said Air India's Hong Kong manager, Dhanoo Khusrokhan. As well as charitable work, the airline pays special attention to elderly and unaccompanied young travellers. Both groups are looked after by flight attendants who each speak several Indian dialects and other languages. This attention to detail has paid off. Earlier this year, the airline flew from Bombay to Osaka, via Delhi and Hong Kong, only twice a week. In April and June, it added two more flights a week, which end in Hong Kong, and hopes to open a fifth in October. Growing demand from businessmen, Hong Kong's Indian community and visitors from the sub-continent prompted the airline to plan still more flights and a bigger fleet, Ms Khusrokhan said. Air India will replace its A310s on the Osaka route with 747s in 1994, when Osaka's new airport opens. Within the next two years, the airline hopes to start flying again from Bombay to Perth, and to open routes to Seoul via Hong Kong and direct to Beijing. Three 747-400s are due for delivery by the end of the year and a fourth will arrive in June 1994. They will be used to replace other 747s on the routes west of India.