Air Canada is finalizing contingency plans to suspend most of its operations.

The airline says contract talks with the Air Line Pilots Association (ALPA), representing more than 5,200 pilots at Air Canada and Air Canada Rouge, are nearing an impasse.

Unless an agreement is reached by Sept. 15, Air Canada said in a press release, the union could issue a 72-hour strike notice, or the airline could issue a lockout notice. Either will trigger the carrier’s three-day winddown plan.