British Airways cabin crew who have been on strike have returned to work for one day before the next five-day stoppage begins on Sunday.
It comes after talks between the airline and the Unite union ended without an agreement.
The two sides are locked in a row over pay, staff levels and work conditions.
Despite the brief break before the second five-day strike, dozens of BA flights scheduled for Saturday are still set to be cancelled.
The airline described Saturday as a "breather" day and said although the "vast majority" of flights were running it was impossible to run a full schedule.
A spokeswoman said: "The large majority of flights to and from Heathrow today will operate as normal and customers will be able to travel as planned. All flights will operate at Gatwick and London City over the weekend.
"The knock-on impact at Heathrow is far less than anticipated due to the numbers of cabin crew who came to work as normal over the past week."
On Friday, conciliation service Acas said talks had been adjourned and it would now try to arrange futher negotiations.
The Unite union says 121 flights out of 333 scheduled to leave Heathrow on Friday have been cancelled.
But in national newspaper adverts published on Saturday, BA said it had flown 325,000 passengers this week. It said it flew to 87% of its long-haul and 100% of its short-haul destinations during the walkout.
"Together, we are confident that we will keep flying through any further industrial action," BA added.
The airline has also said it will increase its flying schedule next week as more cabin crew than expected had decided to work as normal during this week's industrial action.
A third five-day strike is due to start on 5 June.
Unite has said it will call off the industrial action if the airline restores travel concessions to staff who previously went on strike.
Joint general secretary, Derek Simpson said this would not cost the airline anything, and accused BA chief executive Willie Walsh of "blocking a deal".