Air Canada began canceling dozens of flights in advance of a planned strike by its 10,000 flight attendants that could begin at midnight on Saturday morning.

A complete shutdown could disrupt 130,000 travelers a day, including international travelers heading to and from Canada. Air Canada Express flights, which are operated by Jazz Aviation and PAL Airlines and serve regional destinations, would not be affected.

Here’s what you need to know if you’re scheduled to fly on Air Canada in the coming days.

Why are Air Canada flight attendants threatening a strike?

Flight attendants are seeking improved wages and compensation for work they do before flights take off and after they land. (Historically, flight attendants have been paid only for hours that they are in the air, and not for work done during boarding or deplaning, though some major U.S. airlines, including Delta and American, have adjusted some of those policies in recent years.)

Will all Air Canada travelers be affected?

No. Travelers on regional flights operated by Air Canada Express will not be affected, since those flights are subcontracted to smaller carriers. Those regional flights make up about 300 of Air Canada’s 1,000 daily flights.

Are any other airlines affected?

Flights that include Air Canada or Air Canada Rouge, a low-cost subsidiary, may be impacted by the labor dispute, and passengers should check their flight status for any cancellations or disruptions.

Air Canada is part of the Star Alliance, which includes more than 20 partnering airlines like Lufthansa and United. Even travelers on other airlines should check if their flight is code-sharing with or operated by Air Canada, which could cause disruptions.