Cabin crew at British Airways have begun the first of a series of strikes after last-ditch attempts to resolve the dispute collapsed at the weekend.
Passengers using the airline face disruption as the first five-day industrial action gets underway.
Unite had offered a last-minute deal to call the strike off. They said the restoration of travel perks for BA staff, withdrawn after their involvement in March's strikes, would be sufficient to see the strikes called off.
BA rejected the offer, meaning the strike is now taking place. Only a small number of flights from London Heathrow are expected to be affected, however.
"We have already offered to reinstate travel concessions to cabin crew once all elements of our offer have been implemented," a BA spokesman said.
Relations between the airline and the Unite union plumbed new depths over the weekend. First talks were disrupted by a Socialist Workers' party protest, then a row broke out over Twittering from within the private meetings.
Further five-day strikes are set to begin on May 30th and June 5th.
Last week BA posted losses of £531 million, its worst annual results since its privatisation. The long-running dispute has already cost BA some £43 million.