The latest attempt to secure an agreement between British Airways and the Unite union has failed, the conciliation service Acas has said.
Acas had given both sides a new set of proposals last week, but said that "regrettably" they were unable to break the deadlock and move closer to a deal.
It said no new meetings were currently planned, but that it would monitor developments.
Cabin crew workers have staged 22 days of strikes so far this year.
The industrial action was triggered by changes to staffing levels, but currently centres on the removal of travel concessions from striking workers.
Unite has threatened to ballot over further walkouts in July if no agreement is reached with BA.
"Unite remains committed to finding a settlement which addresses its members' concerns," said a spokesman for the union.
"We remain in touch with Acas and with British Airways to that end."
BA said it remained available for talks.
The industrial action has cost the airline an estimated £150m. It recently said passenger numbers were 14.2% lower in May than a year earlier.
Acas said it would continue to offer its services to both sides.