BA has pledged that more than three-quarters of its passengers - more than 180,000 out of 240,000 - will still be able to travel as planned during the walkout, which follows a similar three-day action last week.
A further 18 per cent of customers have been rebooked with other airlines, or have switched their travel dates to avoid the strike period, it said.
Willie Walsh, the BA chief executive, insists the company could fold in a decade unless the changes he wants take place.
He said the "vast majority" of staff were "pulling together to serve our customers and keep our flag flying".
"At the same time, I feel really sorry for those customers whose plans have been ruined by the Unite union's completely unjustified action."
Amid growing hostility between BA and Unite, the trade union which represents BA's 12,000 cabin crew, it has been claimed that the cost to the strike to the airline would be £100 million ($149 million).
By contrast, BA said on Monday that the walkout from last Saturday would cost £7m a day and that an assessment of the cost of the full seven-day action could only be made after it was finished.
Talks between the two sides broke down on the eve of the first strikes, and relations have become increasingly bitter.
Unite said on Saturday that the airline's proposed reforms would leave staff unable to offer the service BA is famous for, saying: "Willie Walsh's slash-and-burn strategy is undermining the brand that BA has built over recent years."
However, Walsh said that changes to working conditions were vital to the company's survival.
"We are trying to transform the way we operate because the industry is changing and the economic conditions have changed so radically that we've got to change," he told the UK's Daily Telegraph newspaper.
"We're doing this to make sure BA still exists in 10 years. If we don't do this, BA won't exist in 10 years."
The strike by Unite members has embarrassed Gordon Brown, the British prime minister, as the union is the governing Labour party's largest financial backer.
Memories of unrest
Tim Friend, Al Jazeera's correspondent in London, said: "Brown is desperate for a settlement.
"What his party fears is of people being reminded by the opposition about the kind of industrial unrest that Labour administrations have had to deal with in the past."
"Labourites fear that the general public will blame them for allowing this to happen - by letting the unions take advantage of the situation - and they will suffer at the polls.
"That may not be true, but that is the fear that the people advising the PM fear, so he is looking for a quick settlement."