CUPE says it has asked the Federal Court for a judicial review of Transport Canada's decision to allow Sunwing to reduce the number of flight attendants by 20 per cent, to one attendant per 50 passengers.
National president Paul Moist called the decision to grant exemptions from the current thresholds "illegal" because they ignore criteria set out in the Aeronautics Act.
"Granting exemptions to Sunwing and WestJet is clearly not in the public interest because it compromises the safety and security levels currently in place," he said in a news release, adding the government is favouring airline profits.
With the matter before the courts, the union said applications by Air Canada (TSX:AC.B) and Air Transat (TSX:TRZ.B) must be "put on ice."
WestJet Airlines (TSX:WJA) received an exemption from the ratio of one flight attendant per 40 passengers in May and has been flying under the new ratio since Oct. 1.
Air Canada said the exemption for narrow-body plane flights within North America would put the airline in line with aviation standards in other jurisdictions, including the United States and Europe.
"In no way does it diminish Air Canada's first priority which is the safety of our passengers and crew," said spokeswoman Isabelle Arthur.
She said the move won't result in layoffs and doesn't apply to international flights using wide-body aircraft, which are governed by collective agreements and Transport Canada regulations.
WestJet said it reduced the number of flight attendants through early retirements and buy-outs, without resorting to layoffs.
The Calgary-based airline has not specifically said how much money will be saved.
Air Transat said its U.S., British and European counterparts already use the lower ratio of flight attendants as a minimum.
"Air Transat is keeping in step with what is now standard practice in other Western countries," said spokeswoman Debbie Cabana.