"The Air Canada strike helps negotiations everywhere. It defined the problem of ridiculous expectations for flight attendants to work without pay," said Sara Nelson, international president of the Association of Flight Attendants-CWA, which represents 55,000 flight attendants at 20 airlines, including United.

Air Canada has already begun canceling flights after hitting an impasse in contract negotiations with the flight attendants' union as a possible strike looms. Earlier this week, the union issued a notice of intention to strike,

After months of stalled negotiations, 10,000 Air Canada flight attendants walked off the job early Saturday morning. The federal government stepped in hours later to order binding arbitration, forcing an end to the strike — or so they thought.

The Canadian government has urged Air Canada and its flight attendants' union to restart contract negotiations, with a threatened work stoppage that could disrupt travel for tens of thousands just hours away unless there is a resolution to the dispute.