British Airways pilots' planned strike may cost the airline as much as US$50 million a day, the airline said in a lawsuit as it seeks to halt the walkout.

Pilots at the airline backed industrial action -- including what would be their first strike in about four decades -- with a 93% majority, the British Airline Pilots Association said Monday.

While it's impossible to accurately assess the costs, it'll be "very substantial indeed," running to between 30 million pounds (US$37.4 million) and 40 million pounds a day, the airline said in its filings for a hearing at London's High Court. BA is seeking an injunction to halt the strike, which it expects to start on or soon after Aug. 7.

"The industrial action will be enormously disruptive" for the airline and for passengers, John Cavanagh, the airline's attorney, said Tuesday in court.

"There can be no doubt that the timing of the action is deliberate and is designed to cause the maximum in financial loss and disruption for BA," the airline said in court filings. "The action is due to commence in peak holiday period, in the middle of school summer holidays, and at the busiest time of BA's year."

Pilots' demands in the labor dispute relate to pay, profit sharing, and a share-awards program.

It'd "cost less to agree every item we have put forward than it would cost BA if there was just one day of strike action," a union spokeswoman said. "It is surely time for common sense to prevail over the macho management we have seen up till now."

The airline, part of International Consolidated Airlines Group SA, said the labor union had failed to comply with balloting rules, meaning the court should grant the injunction. The union said it wasn't obliged to provide the information that the airline contends it should've -- including the dates of industrial action.

"We continue to pursue every avenue to find a solution to protect our customers' travel plans and avoid industrial action," BA said in a statement.

- With assistance by Benjamin D Katz, and Simon Foy