Air Canada is preparing to suspend most of its flights starting next Sunday as it faces a likely impasse in talks with its pilots over wage demands, the company said.

The nation's flagship carrier and the union representing more than 5,200 pilots remain far apart on a deal after 15 months of ongoing negotiations.

In a statement, Air Canada said Monday "it is finalizing contingency plans to suspend most of its operations."

The carrier said flights across its network could be gradually cancelled starting Sunday, before a total shutdown effective at midnight (0400 GMT) on September 18 if a strike notice is filed by the union or if there is a lockout.

The airline's pilots, who voted in August to strike if talks fail, are pushing to close a pay gap with their American counterparts, but Air Canada says their demands "far exceed average Canadian wage increases."

The Air Line Pilots Association (ALPA) union, in a statement to AFP, accused Air Canada of threatening to disrupt flights over "corporate greed," saying the airline has earned record profits "while expecting pilots to accept below market compensation."

Air Canada flies to 47 countries and carries an average of 110,000 passengers a day on its 670 flights.