Heathrow was badly hit by last month's strike - which will cost up to £45m
Talks between British Airways and the Unite union aimed at resolving the cabin crew strike have resumed, Unite has said.
Joint general secretary of the union Tony Woodley said "serious progress" had been made and discussions would continue over the next few days.
Cabin crew went on strike for seven days last month over pay and working conditions.
On Wednesday, BA said the strikes cost it between £40m and £45m ($61m-$68m).
Unite said talks with BA had resumed over the Easter weekend and are ongoing.
"It is welcome that talks have resumed and I am pleased that some serious progress has been made over the issues that have divided us," said Mr Woodley.
He added that no further strike dates would be set while the talks continued.
In its latest traffic statement for March, BA said it managed to fly 79% of long-haul flights and 58% of short-haul flights during the strikes.
Its monthly traffic figures also showed the airline carried 14.6% fewer passengers than in March last year.
About half of the fall was as a result of planned winter capacity reductions, BA said.
BA and the Unite union are in dispute over the airline's cost-cutting plans, which include reducing the numbers of cabin crew on long-haul flights.
Analysts say BA needs to bring down its costs significantly.
The airline is expected to announce the biggest loss in its privatised history when it reports its annual results later this year. Last year it lost more than £400m.
The financial impact of the recent strike not only includes lost revenue, but the cost of hiring in planes and crew, as well as buying seats on rival carriers.