More than 200 flights in and out of Heathrow have been cancelled on the second day of strike action by British Airways cabin crew.
Nearly 200 short-haul flights and around 28 long-haul flights scheduled for Tuesday have been cancelled, departure boards suggest.
BA refused to confirm the numbers, saying that they preferred to concentrate on passenger numbers.
The airline said its contingency operations were going to plan.
It said it was flying 60,000 passengers a day - equivalent to 70% of the total typical for this time of year.
The airline also said it was meeting its target of flying more than 50% of short-haul flights and 60% of long-haul flights from Heathrow.
The cabin crew's union, Unite, called the strike "well supported", saying that a total of 473 long-haul cabin crew did not turn up to work on Monday.
A total of 361 did show up, the union said, though these included temporary crew, international crew not on strike and what they termed "strike-breakers".
On short-haul routes, 274 staff did not report to work, Unite also said.
BA said it did not recognise these figures, adding that it had more crew than necessary to operate its contingency plan, allowing it to add more flights.
Appeal for talks
"The flights are crewed by union cabin crew members who do not support the strike, cabin crew who are not members of the union (be they UK or international crew) and fully-trained volunteer cabin crew," a BA spokesman said.
Unite says strike action so far this year has cost BA at least £63m, based on a loss of £7m a day over the nine days of industrial action.
Unite's joint general secretary Tony Woodley called on BA's chief executive Willie Walsh to "waste no further time or resources" on fighting the strike and instead return to the negotiating table.
No talks between Mr Woodley and BA's chief executive Willie Walsh are currently taking place, though a meeting is expected to be planned for later this week.
Earlier talks broke down, with the reinstatement of travel perks for workers involved in previous strikes still the biggest sticking point.
Mr Walsh has blamed Bassa, the branch of Unite representing cabin crew, for scuppering a deal that has broadly been agreed with Unite's leadership.
Speaking to the BBC, the secretary of Bassa, Duncan Holley, said his branch had the final say over any agreement between Unite and BA.
He said the latest deal had been rejected because of the mistrust of Willie Walsh from within Bassa.
"The relationship between us and Willie Walsh is so bad that we need clarification on every minor detail," Mr Holley said.
"Everyone sees Willie Walsh as the problem."
Mr Holley, who was sacked by BA three weeks ago, said that Bassa were not negotiating directly with BA, but had complete faith in Unite's leadership.
"Tony Woodley has given us the final say on whether we accept the deal or not," he said.