WestJet may start grounding flights as early as tomorrow unless a deal is reached with the union representing 4,400 flight attendants.

CUPE has issued a 72-hour strike notice, which was followed by a 72-hour lockout notice issued by the airline.

WestJet, which operates more than 600 flights daily, including several out of St. John’s and Deer Lake, is expected to begin the wind-down process tomorrow.

Those booked on flights between now and Tuesday can change or cancel their plans at no additional cost.