British Airways cabin crew have entered their 20th day of strike action this year, with no sign of agreement between the Unite union and the airline.
Monday is the third day in the latest five-day strike action, which is due to end on Wednesday.
Unite has threatened to hold a fresh ballot among its members on further strike action, which could disrupt flights during the summer.
The long-running dispute is over staffing levels and working conditions.
The current strike action is the third and last in the current series of walkouts.
Over the weekend, BA said it had been able to operate extra flights as more cabin crew than expected had turned up for work.
"Our global operations went very well last week and we have got off to another good start at the beginning of this strike period," BA said.
The airline said it had been able to operate more flights to Los Angeles, Washington, Mexico City and Phoenix over the weekend, and would continue to operate all flights at Gatwick and London City airports.
BA has said it plans to fly more than three-quarters of customers who booked flights during the current strike period.
Last week, the airline announced that the number of passengers it carried in May fell by 14.2% from a year ago, partly due to the strikes.
BA carried a total of 2.37 million passengers in May, down from 2.76 million a year earlier.