THE holiday season is always a difficult time to get a seat on an aircraft unless bookings have been made well in advance and, with Canadian Airlines, it can become even more of a problem. If you are thinking of taking a flight to Vancouver between now and mid-September on economy class, you may as well forget it, according to Richard Webb, the airline's general manager in Hongkong. Mr Webb said despite the usual holiday makers around this time of the year, finding room on Canadian Airlines was compounded by people emigrating to Canada. Passengers can fly on Boeing 747-400s from Vancouver to Hongkong daily. On six of these days, the flight continues to Bangkok. Although passengers flying from Hongkong to Toronto have to change aircraft at Vancouver, they do not have to clear immigration and customs until Toronto. Despite the high passenger capacity - the envy of many other airlines - Mr Webb said that the airline had no plans to expand the number of flights in and out of Hongkong. ''We increased our seating capacity in May 1991 when we introduced Boeing 747-400s to replace DC10s on three flights a week between Hongkong and Vancouver,'' he said. ''The number of flights increased to two DC10 and five 747-400 last year, and the arrival of another 747-400 at the end of 1992 allowed us to fly daily 747 flights and increase our capacity this year by 290 seats a week.'' Mr Webb said that this would be sufficient for the next two years on the Hongkong-Canada route. However, elsewhere in the region, Canadian Airlines had taken substantial steps to increase its services. The service to Taipei, which began with two DC10 flights a week in 1991, now had five flights. The two-flights-a-week service from Nagoya to Vancouver was increased to six a week from the beginning of last month. At the the same time, the airline began operating six flights a week from Tokyo to Toronto, a route which it had previously shared with JAL. Canadian Airlines is also planning to resume its services to Beijing in the spring, after the purchase of a 747-400. Through its predecessor, Canadian Pacific Airlines, Canadian Airlines has provided a scheduled service to Tokyo and Hongkong since 1949. Canadian Airlines is a privately run airline and the national carrier. It was formed in 1987 by the amalgamation of Nordair, Eastern Provincial Airways, Canadian Pacific Air Lines and Pacific Western Airlines: airlines which, between, them flew charter, domestic and international flights. This was followed, in 1989, by the acquisition of Wardair Canada, an airline which brought with it a string of European routes. A partnership with Canadian Regional Airlines, a commuter airline, has provided a feeder network operating from 150 airports across Canada. The airline's focus in the 1990s is globalisation. Part of this policy includes an alliance with American Airlines in an aim to improve competitiveness in Canada. The Canadian National Transport Association has approved the alliance, and Mr Webb said negotiations were expected to be completed by next month. Canadian Airlines already operate a large number of charter flights to United States' airports, particularly in the winter to Florida, and the link up with American Airlines will expand the network in the United States. Like most airlines, Canadian offers a frequent-flier programme. It is known as Canadian Plus. This enables people who fly regularly with the airline to accrue mileage credits, which can be used for free flights, hotels and holiday packages. Although the alliance with American Airlines has not been finalised, the frequent fliers' programmes of both airlines became interchangeable last month.