British Airways (BA) has said it plans to fly more than 70% of customers during the upcoming five-day strike.
The strike will last from May 18 to 22.
BA says more than 60,000 customers each day will get to their destination.
Flights at Gatwick and London City airports will continue as normal.
More than 60% of longhaul Heathrow flights will operate, and 50% of shorthaul.
BA said it would add to the schedule where possible, and that the airline will fly to every shorthaul destination on its network.
The airline has also made arrangements with more than 50 other carriers, to rebook customers during the strike onto other flights.
Before the previous round of strikes, in March, BA pledged to fly a fewer number (60%) of passengers, but by the final two days the airline said it was actually flying 75% of customers.
The airline has been training volunteer cabin crew, to replace striking staff, since the initial set of walkouts.
The airline is still available to hold further talks with Unite but wants customers to have early warning of its flying schedule to allow sufficient time for alternative travel arrangements to be made.
Customers flying to/from Heathrow on a longhaul flight between May 18 and May 23 can now check their bookings on www.ba.com to see if their flight is still operating. The revised shorthaul Heathrow schedule between May 18 and May 23 will be available for customers on our website at 10am on Friday May 14.
Willie Walsh, British Airways' chief executive, said the decision to strike is "disproportionate" and accused Unite's leaders of deliberately targeting half term hoidays "to cause as much disruption as possible".
"We are confident that many crew will ignore Unite's pointless strike call and support the efforts of the airline to keep our customers flying... Due to the numbers of cabin crew who are telling us they want to work normally since Unite's latest strike call, the schedule will be slightly larger than we had originally anticipated." said Walsh.
"As the new government starts addressing the enormous economic challenges facing the country, it is sad that Unite's priority is to seek to damage Britain's links with the world.
"We remain absolutely determined to resolve the dispute and our door remains open to Unite, day or night. It is not too late for Unite to call off this action and protect its members' job security."
BA has set up a phoneline to help customers with refunding and rebooking queries: 0800 727 800.