(Calgary) WestJet is cancelling flights in anticipation of a possible strike by the mechanics’ union.

The Calgary-based airline said in a statement Wednesday evening that the Aircraft Mechanics Fraternal Association has served it with another strike notice.

As a result, WestJet has preemptively cancelled 25 flights scheduled for Thursday and Friday. Approximately 3,300 customers will be affected.

The move comes as the Aircraft Mechanics Fraternal Association accuses WestJet of suing it without informing negotiators working with the airline to develop a new collective agreement.

The union calls WestJet’s statement that a strike would put it and travelers at risk “inflammatory,” and is calling on WestJet to spend more time negotiating with union representatives.

Union members overwhelmingly rejected a tentative agreement earlier this month and opposed WestJet’s request for arbitration.