Air Canada has been ordered to pay a French-speaking couple of 21,000 Canadian dollars ($ 15,700; $ 12,900) and write them an apology letter for violating their linguistic rights.
The couple complained that some signs of a domestic flight they took were only in English, while others gave the French version less prominence.
A judge ruled that the airline had violated Canada's bilingual laws.
Air Canada allegedly told the court it would work to replace the signs.
The Ontario couple and Lynda Thibodeau filed 22 complaints against the airline in 201
Among them, they argued that the word "lift" was engraved on the buckle of seatbelts in English, but not in French, while French translations of words such as "exit" was in minor grades.
They also said the English-language boarding message for their Montreal-bound flight was more thorough than the French version.
"Air Canada is systematically violating the linguistic rights of Francophones," the couple argued, according to the written judgment on the case.
In the ruling, a judge in Ottawa declined that the airline had not "maintained its linguistic obligations".
Air Canada is subject to the country's official language law, which seeks to ensure that English and French receive equal status.
The airline had claimed that the couple interpreted the action too strictly, according to court documents.
In an interview with the Canadian broadcaster CBC, Mr. Thibodeau said he was happy with the verdict, but hoped to see signs of Air Canada flights improving in the future.
"Signs must be of the same quality," he said. "My expectation is that in a few months we will be able to fly on all Air Canada flights, and eventually signage will be in both official languages."
This is not the first time the couple has accused the airline of violating their linguistic rights. In 2014, the Supreme Court ruled that they could not sue Air Canada over an incorrect drink order on an international flight and had to settle for an apology, the Toronto Sun reports.