Air Canada offered its flight attendants an overall increase of more than 30% over four years ahead of a potential strike, according to a person familiar with the negotiations.

Air Canada flight attendants want to make gains on unpaid work that go beyond recent advances secured by their U.S. counterparts, a union leader said on Wednesday, in a fresh test of the way airlines compensate cabin crews.

The Air Canada component of the Canadian Union of Public Employees says members voted 99.7 per cent in favour. The mandate does not mean that a strike is guaranteed, only that union members support the measure if the bargaining team decides to call for a work stoppage.