British Airways (BA) has been forced to cancel all passenger flights out of Heathrow for two days next week because of a strike by thousands of cabin crew.
Domestic and European flights to and from Gatwick will also be grounded on the two days - Tuesday and Wednesday - following the breakdown of talks aimed at resolving a bitter row over sickness absence, pay and staffing.
BA chief executive Willie Walsh said: "We are deeply sorry that our customers are the innocent victims of this unnecessary and unjustified strike."
The airline said it will allow any customer due to travel on a British Airways flight cancelled by the strike to claim a full refund, rebook their flight for a later date or be rebooked by BA with another airline.
BA said customers due to travel on a cancelled service should not go to Heathrow or Gatwick.
The carrier warned of further cancellations on either side of the official strike dates because crew and aircraft will be out of position.