(FORTUNE Magazine) – The deregulation of U.S. airlines is causing turbulence in Europe. Says John Pincavage, industry analyst for Paine Webber: ''The Europeans have seen the advent of the U.S. megacarrier, and they realize they aren't competing with just Pan Am anymore. We'll see more collaboration.'' Some carriers will take the merger route. British Airways plans to buy its smaller rival, British Caledonian, for about $390 million. Another likely union: Sabena, Belgium's national airline, and SAS, the Scandinavian carrier. Collaborations of the marketing sort will give both U.S. and European airlines more range. Swissair, British Airways, and KLM Royal Dutch Airlines have teamed up with United to launch a European reservation system. Total cost: $120 million. Texas Air recently joined with Air France, Lufthansa, Iberia, and SAS to spend $300 million on a similar system called Amadeus. The airlines plugged into these systems, which will list all carriers, will profit by getting passengers from their partners. That leaves American Airlines, whose Sabre system was the first in computerized reservations, standing at the gate. American may have lost more than its reservation-systems business. Says Timothy Pettee, industry analyst for Bear Stearns, the New York investment house: ''A U.S. airline hoping to market successfully in Europe has got to have some input or share of the European distribution system.''