British Airways yesterday said Unite's three-day strike would cost it around £21m.
The airline faces a £7m-a-day bill under its “current best estimate” of the impact of the industrial action.
BA added that contingency plans to cope with the strike had been “very successful”, and results for the year to March 31 would be “broadly unchanged”.
Based on yesterday's estimates, BA would be left with a total bill of almost £50m if the four-day strike, due to start on Saturday, goes ahead although the airline said the cost of any action could only be assessed after the event.
Over the first two days of the action, BA said it operated 273 or 78% of long-haul flights and 442 or 50% of its short-haul flights.
The airline also ran 70 positioning flights — which in most cases carried cargo — to return passengers home with minimum disruption.
The company said it began the weekend with 82,573 bookings for the two days, after reservation teams worked with customers to reduce bookings, although it actually carried 86,262 passengers after late bookings.
The update from BA is the latest shot in the row between Unite and the airline over the |impact of the strike.
Although BA said the outlook for the year was unchanged, it remains on course for record losses this year after racking up a pre-tax loss of £342m in the nine months to December 31.
The latest slide into the red follows losses of £401m in the 12 months to last March as the firm was hit by the recession.
Leaders of British Airways cabin crew last night urged the airline's chief executive to “come out of his bunker” and hold fresh talks as the three-day strike over jobs and cost-cutting came to an end.
Tony Woodley, joint leader of Unite, said he had not received any positive response from the company to his plea for fresh talks and added that chief |executive Willie Walsh's silence was “deafening.”
Striking staff were in buoyant mood at a rally at Heathrow Airport, many booing BA flights as they passed overhead and joining in various chants aimed at Mr Walsh.
BA said yesterday: “Cabin crew are continuing to report as normal at Gatwick, and Heathrow levels remain above what we need to operate our published schedule.”