British Airways Plc and American Airlines quietly settled their differences last week, and American withdrew its litigation against the UK flag carrier. American had complained that the fact dhat the only reservation system able to issue British Airways tickets was the airline’s own Travicom system amounted to restraint of trade. Under the settlement, American’s Sabre reservation system will be able to machine-issue British tickets, and in return, American has agreed to change the way Sabre displays the flights of British Airways to give them more prominence. The settlement will make it more attractive for UK travel agencies to install terminals to the US Sabre system.