British Airways cabin crew have begun strike action that will cause severe disruption to flights for the next three days, BBC reported
Talks between the airline and the Unite union, which represents the crew, collapsed on Friday.
A further four days of action are set to begin on 27 March, although BA has said this weekend's action could disrupt flights into next week as well.
Cabin crew are striking over pay and working conditions.
BA says that 65% of passengers will still be able to reach their destination during the first three-day strike, even though a total of 1,100 BA flights out of the 1,950 scheduled to operate will be cancelled.
At Gatwick, all long-haul flights and more than half of short-haul flights are expected to operate as normal.
At Heathrow, more than 60% of long-haul flights will operate, though only 30% of short-haul flights are expected to do so, with the help of aircraft leased from rival airlines.
Uncertainty still exists about just how many BA crew will go on strike after BA said that any staff who took part in strike action would lose perks, including heavily-discounted travel fares.
BA says that it is confident that it can handle 49,000 passengers on each of Saturday and Sunday, compared with around 75,000 on a normal weekend day in March.
In a video message on the BA website, chief executive Willie Walsh apologised to passengers for what he said was a "terrible day" for the airline.
However, he said he was confident that a "good service" would be provided.
Mr Walsh and Unite union joint general secretary Tony Woodley failed to reach an agreement to avert action on Friday in the increasingly bitter dispute.
After the talks failed, Mr Woodley said Mr Walsh wanted to "go to war" with the union. Mr Walsh dismissed the claim as "absolute nonsense".
Mr Woodley had called on BA to put an earlier deal to end the strikes "back on the table", which he said would have allowed him to call off the strike while union members considered it.
Instead, Mr Walsh offered a less attractive deal to compensate the company for the costs already incurred in making alternative arrangements for some passengers to fly during the strikes.
Mr Woodley called the revised offer a "disgrace and an insult", and refused to present it to union members.
Among the passengers inconvenienced is James Alexander, from Newcastle, who is due to emigrate to Australia with his partner on Monday, the last day of the strike.
He said: "I've told them today on the phone I'll never fly BA again. Never. Just purely as a matter of principle now. This is chaos."
BA has been in negotiations with Unite for many months.
Workers are particularly angry that last November BA reduced the number of crew on long-haul flights and is introducing a two-year pay freeze from 2010.
The airline also proposed new contracts with lower pay for fresh recruits.
Unite says it accepts the need for BA to cut costs, but that it was not consulted on the changes.
BA suffered a loss before tax of £342m for the nine months to the end of December 2009 and says it needs to cut costs in order to survive.