Air Canada says it will begin cancelling flights starting Thursday to allow an orderly shutdown of operations with a complete cessation of flights for the country’s largest airline by Saturday as it faces a potential work stoppage by its flight attendants.

The Montreal-based airline said labor negotiations with its 10,000 flight attendants are at an impasse and warned that the carrier may begin to shut down operations as early as Saturday without an agreement.

Air Canada is preparing to halt most of its flights after its flight attendants' union served a 72-hour strike notice on Wednesday, warning of a walkout as contract talks over a pay deal stall.