Air Canada flight attendants’ union has notified the airline of a three-day strike after negotiations over pay increases broke down. The strike is set to begin August 16, with 99.7% of union members—more than 10,000 flight attendants—voting in favor.

According to the union, while some progress was made during talks, key issues remain unresolved. A major point of contention is compensation for all hours worked, including duties outside of flights, such as boarding passengers. Currently, Air Canada only partially pays for these duties, whereas the union is demanding full pay for the entire workday.

The airline proposed an overall compensation increase of 25% in the first year and 38% over four years, including benefits and bonuses, but the union says the offer still falls below inflation. Notably, Delta Air Lines became the first U.S. airline to pay flight attendants for passenger boarding.

If the strike proceeds, it could lead to the cancellation of around 700 flights per day, affecting roughly 130,000 passengers. Regional flights operated by third-party carriers under Air Canada Express will not be impacted.