MONTREAL -- Air Canada's machinists union wants the country's labour relations board to ensure it represents workers at the airline's low-cost subsidiary Air Canada Rouge and Sky Regional Airlines, an privately owned partner.

The International Association of Machinists and Aerospace Workers is filing two applications with the Canada Industrial Relations Board for have Air Canada declared the single employer for both airlines.

One application is designed to ensure the union continues to represent its members at Rouge after the current contract expires in 2016. The other seeks to represent non-unionized mechanics and baggage handlers at Sky Regional, which uses Air Canada (TSX:AC.B) aircraft on routes in Canada and the United States.

IAMAW general chairman Fred Hospes says the union is trying to "protect work done by our members and their jobs at Air Canada."

The union contends Sky Regional and Rouge were created to fly Air Canada planes and routes at lower costs, but are controlled and directed by the country's largest airline.

The IAMAW is the largest union at Air Canada representing more than 8,800 workers, including line maintenance mechanics, auto mechanics, baggage handlers, cargo agents, aircraft cleaners, cabin groomers, millwrights, electricians and technical writers.

Launched last July, Rouge serves routes to sun destinations and Europe. With more seats, lower wages, more flexible work rules and lower overhead, Rouge flights are cheaper to operate than Air Canada's main network.

Operating under the Air Canada Express banner, Sky Regional operates flights between Montreal and Billy Bishop Toronto City Airport as well as flights mainly from Toronto and Montreal to the U.S. Northeast.