VANCOUVER - WestJet has lost an appeal of a court decision that refused to throw out a proposed class-action lawsuit that accuses the airline of fostering a culture that tolerates harassment of female employees.

Former flight attendant Mandalena Lewis is suing over alleged gender-based discrimination. She claims her former employer broke its promise to provide a harassment-free workplace for women.

A British Columbia Supreme Court judge dismissed WestJet's application to strike the legal action in 2017, rejecting the company's argument that the dispute belongs before a human rights tribunal and workers' compensation board.

The airline took its argument to the B.C. Court of Appeal and a three-judge panel ruled against it Thursday. The panel said in a written decision that nothing in the relevant statutes removes the jurisdiction of the courts in this case.

None of the allegations contained in the lawsuit have been proven in court.

WestJet spokeswoman Lauren Stewart said in a statement that the company respects the decision of the Appeal Court and is in the process of reviewing the ruling with its counsel to determine next steps.

The lawsuit proposes to represent all of WestJet's past and current female flight attendants whose employment contract included a so-called anti-harassment promise. The case has yet to be approved by the court as a class-action proceeding.

The Appeal Court ruling rejected the airline's argument that the plaintiff's allegations fall within the mandate of the Canadian Human Rights Act, which enforces employee rights related to discrimination and harassment.

Appeal Court Justice David Harris said although the alleged facts of the lawsuit involve discrimination and harassment, the primary allegation is a breach of contract.

“A contract is a recognized source of legal rights grounding remedies for breach in the courts,” he wrote on behalf of the panel.

Lewis said she was elated by the court's decision. She described it as “history-making” because it recognizes the importance of employers' contractual promises to employees, particularly those about keeping women safe from harassment and assault.

“This is a win for women everywhere,” she said. “This lawsuit is definitely already setting a precedent for how employees are dealing with sexual harassment complaints.”

She said she hopes the class-action will be certified within the next year.

Her statement of claim against WestJet alleges she was sexually assaulted by a pilot while on a stopover in Hawaii in 2010.

WestJet has rejected allegations that it failed to take appropriate action after she reported what happened.

The Calgary-based airline's statement of defence said it immediately launched an internal investigation into Lewis's complaint, but the company was ultimately unable to conclude the pilot had committed an assault.

Lewis, 33, said Thursday that she filed the lawsuit because she “couldn't be quiet.”

“I had been through too much myself and I was trying to make a difference within the company.”