Western European airline pilots today rallied behind a call to impose a two-month boycott on flights to Moscow to show their outrage over the Soviet Union's shooting down of a South Korean airliner with 269 people aboard.

British Airways may be compelled to suspend its four weekly flights to Moscow because the Association of British Pilots announced today that its 4,500 members will boycott the route for 60 days starting Friday.

The Scandinavian airline, SAS, said that pilots from Norway, Sweden and Denmark have informed the company that they intend to carry out a two-month ban on flights to Moscow beginning Monday.

The International Federation of Air Line Pilots Associations, representing 57,000 pilots in 67 countries, recommended the boycott yesterday after coming under intense pressure from rank-and-file members to take tough action against Moscow for shooting down the passenger jet that strayed into Soviet airspace.

The pilots' angry desire to ostracize the Soviet Union has caused some discomfort among Western European governments that share the pilots' outrage over the incident but want to avoid sanctions that may violate treaties or exacerbate East-West tensions.

A spokesman for West Germany's 2,000 pilots and flight engineers said they wanted to join the boycott but could only do so if the national airline, Lufthansa, agreed to waive a contract clause that equates such action with an illegal strike that could cost them their jobs.

In Frankfurt, Lufthansa officials said they needed to consult the government before making any decision but stressed that any cancellation of their 10 weekly flights to Moscow and Leningrad would break the 1971 civil aviation agreement between West Germany and the Soviet Union.

The West German government has condemned the Soviet action but refrained from supporting sanctions on air travel because Moscow could retaliate by disrupting routes to West Berlin. West German officials also believe that further isolation of the Soviet Union would nullify hopes for cooperation from Moscow in other important fields such as arms control.

The European pilots, however, insist that the Soviets must admit their error and take corrective measures.

The French pilots' association today declared that its members will participate in the two-month boycott of flights to Moscow next week unless the government receives firm Soviet guarantees that their future safety will be assured.

Soviet Foreign Minister Andrei Gromyko is expected to arrive in Paris on Friday for talks with top French officials, and the prospect of a boycott is likely to arise in the discussions.

Pilots for Air France, which conducts seven weekly flights to Moscow, have complained about a lack of cooperation from Soviet air controllers, many of whom speak no English and communicate with the pilots through interpreters.

Reuter news service reported from Melbourne, Australia, that pilots in that country had agreed not to allow Soviet diplomats and government officials to travel on domestic flights in Australia for 60 days, beginning Wednesday. The pilots said they could not participate in the ban on flights to the Soviet Union since no Australian airline has any.

The international pilots association plans to review the ban in a month's time and has threatened further measures, including a total boycott of Soviet airspace, unless Moscow promises that no further attacks on commercial aircraft will occur.

"This action is to demonstrate our determination that this must never happen again," said Captain Robert Tweedy, president of the international association. "It is a sign that we are disgusted by the attack."

The association's vice president, John Leroy, an American, said, "I do not believe it is too much to ask of a nation not to shoot civilians."

So far, European capitals have not made any decision to curtail landing rights for Aeroflot, the Soviet national airline, and flights from Moscow to Europe have proceeded on schedule. Soviet flights could be disrupted if European ground and maintenance crews decide to join the boycott.