The transport minister has exempted Air Canada from a rule requiring one flight attendant per 40 passengers on narrow-body aircraft with more than 50 seats.
The exemption lets the airline have one flight attendant per 50 passengers.
The Canadian Union of Public Employees says this means that one floor-level exit would be unstaffed by a flight attendant on certain aircraft, raising serious safety considerations, particularly in the event of an emergency evacuation.
A spokeswoman for Transport Minister Lisa Raitt wouldn't comment because the matter is before the courts, but an Air Canada spokesman defended the exemption.
Peter Fitzpatrick says the one-to-50 ratio is "absolutely safe" and is an internationally accepted standard.