THOUSANDS of passengers travelling between Hong Kong and Canada could be grounded if an Air Canada pilots' strike, set for Tuesday, goes ahead. The airline has announced it is preparing for a strike to begin at midday on Tuesday, Hong Kong time. There is no deadline, but Air Canada initially is offering no-fee refunds to travellers with tickets for flights between September 2 and 6. Air Canada spokeswoman Nicole Couture-Simard said those with seat sale tickets - issued without fixed dates - or on charter fares would be unable to get their money back ahead of time. They would receive refunds if their flight was cancelled by the strike. Passengers on codeshare flights - in which one leg is flown with Air Canada and another with a different carrier - would not be affected. Vancouver-based travel agent Wong Kam-wai said thousands of Hong Kong migrants and visitors would be affected if the strike went ahead. 'Usually, there are many parents and children are rushing back to Canada next week for new school terms after visiting their relatives in Hong Kong. I think they should prepare for the strike,' he said. The Montreal-based carrier has daily flights between Hong Kong, Toronto and Vancouver. Travel Industry Council executive director Joseph Tung Yao-chung said Hong Kong-Canada was a popular route. Although most summer tour packages end in August, hundreds of Hong Kong students could be caught by the strike. 'The school holidays are just over so a lot of Hong Kong students are returning to Canada,' Mr Tung said. 'It will affect student travel a lot.' The airline said yesterday it would continue talks with pilots after unsuccessful mediation talks on Thursday. The Air Canada Pilots Association, representing 2,100 pilots, set up information picket lines at Montreal, Toronto, Calgary and Vancouver airports yesterday. Pilots have also marched with picket signs inside airport terminals. They are seeking higher wages to match US airlines and better working conditions - they have been without contracts since April 1. Union chief Jean-Marc Belanger warned that a full-blown strike would cause mayhem.