Unless the other carriers buy the routes, they would have to negotiate with their home governments and the governments at their destinations.

American, which bought the routes to 20 cities in 15 countries from Eastern Airlines for $330 million, is expected to exploit the market better than did its struggling predecessor.

One of the company's drivers, Frank Fiorina, offered to buy the birch beer formula, the customers and the routes.

He said Delta had been interested only in buying the European routes and the shuttle.

The agreement over the rights to fly into Heathrow was crucial to the sale since United would not have bought the routes without such rights.

United, which bought the routes from Pan American World Airways in 1986, had initial problems with the operation and took some large losses on it.

Just this week United has been negotiating with Pan Am to buy the Latin American routes; other bidders are also on the scene.

American Airlines has agreed to buy the routes for $445 million.

United had also offered to buy the routes from Pan Am late in August for $215 million.

This finally bought all the routes under one ownership.