British Airways argues that it is entitled to reduce the number of cabin crew on board its Worldwide and Eurofleet flights as such a step would not breach individual cabin crew members' contracts.
British Airways cabin crews are reported to have lost a High Court case against cuts to the number of staff serving on the flagcarrier's flights.
Also the union cites implementing such changes would hamper collective agreements with the unions relating to crew numbers, which it said were "expressly incorporated'' into individual contracts.
The case was filed when the airlines called for a new regime in November, cutting its staff by one on all flights and two on some international ones. The judgment from Judge Sir Christopher Holland comes days before the conclusion of a strike ballot protesting against planned job cuts, changes to contracts and a two-year pay freeze.
BA said in a statement, "We are extremely pleased with today's High Court ruling that the modest changes we made to on-board crew numbers on flights from Heathrow were reasonable, did not breach crew contracts and can remain in place".
Unite had revealed to approve unwillingly to work to the new schedules pending today's decision on 10 test cases - representative of about 5,400 claimants who are among 13,400 cabin crew employed by BA.