The board announcing departures at Moscow's Sheremetyevo International Airport today provided a kind of United Nations roll call on the Soviet downing of a South Korean airliner with 269 people aboard.

Absent were Montreal, London, Rome, Frankfurt, New York, Tokyo, Madrid, Stockholm and Brussels. Present were East Berlin, Mexico City, Budapest, Sofia, Algiers, Pyongyang, Havana, Tehran and Conakry.

Also present on the board were Vienna and Paris--the capitals of Western European countries that have condemned the destruction of the airliner but refused to join in the two-week western ban on aviation links with the Soviet Union. That ban began today.

In all, the boycott was being enforced by 13 NATO countries plus Switzerland and Japan, severing Moscow's air links with a large part of the western world. The ban halts Soviet flights to, from and over the countries taking part.

A senior State Department official in Washington said that the countries participating in the boycott accounted for 50 percent of world civil aviation. During the two-week course of the ban, he added, 80 scheduled flights out of a normal 156 in and out of the Soviet Union will be canceled, halting about 30 percent of regular Aeroflot flights to noncommunist countries.

"We're very gratified," he said. "We think it's fairly successful. This won't destroy Aeroflot. But that was never the purpose. We wanted to provide a strong political signal. . . that would put the Soviets on notice that their behavior is unacceptable and must be changed."

Only France, Greece and Turkey refused to join their NATO allies in the action.

Austria and the Soviet Union's Eastern European bloc members all maintained regular services.

Judging by the scene at the modern Sheremetyevo Airport, the boycott looks as if it is going to hurt western tourists more than Soviet citizens. Most Russian travelers questioned at the airport said they were flying to cities in Eastern Europe.

Western travelers who were forced to change or delay their flights because of the boycott gave mixed responses when asked if they thought it was all worthwhile.

Berndt Rodtke, a West German technician who had been put on a flight to East Berlin after finding out that he could not fly Lufthansa to Frankfurt, said he did not see the point.

"What kind of protest is this when it hurts us more than them? I've been here for six months, and I want to go home. Now it looks as if I'll be up all night looking for a train to get me from Berlin to Hannover, my hometown," he complained.

Thomas Schelling, a professor of political economy at Harvard University, was on standby with his wife to fly Austrian Airlines to Vienna after finding out that his Swissair flight to Zurich had been canceled.

"If an action such as this has an effect, I am willing to be a chance victim," he said. "It probably does have some symbolic effect, although not a big one. My impression is that the Soviet government is adamant about its line and is not going to change it."

Underneath the departure board, a crowd of young French tourists lay sleeping on the floor of the main airport concourse, their heads propped up against rucksacks. They had been scheduled to fly back to Paris on Aeroflot this morning after a two-week holiday in Siberia.

But the Aeroflot flight was canceled because Switzerland banned the airline from flying over its territory and the Air France flight--manned by a nonunion crew--was crammed full.

Among the 25 stranded French tourists, opinions were also divided.

"In principle, I think the West is right to protest," said Eric Lenormand of Paris.

Oliver Grundmann said he felt the boycott was "ridiculous. . . . Very few Soviet citizens are allowed to travel to the West anyway. We are the only ones being affected by this boycott."

U.S. diplomats reacted defensively to suggestions that the boycott, which was imposed at President Reagan's urging, is hurting westerners more than Soviets.

"We fully understand that these restrictions are going to cause inconvenience to some people," an embassy official said. "But we feel very strongly that the larger objective--sending a message to the Soviet Union--overrides this inconvenience."

The U.S. Embassy last week barred any employe from flying into or out of Moscow until further notice, except in emergency. Couriers carrying the confidential diplomatic pouch are now required to use trains.

Last Saturday, however, U.S. Ambassador Arthur A. Hartman flew back to Moscow from Madrid aboard a U.S. Air Force plane with supplies for the embassy. An embassy spokesman explained that the flight came under a joint agreement signed in 1982 allowing both the United States and the Soviet Union at least six "service" flights a year to each other's territory.

This agreement has not been canceled despite the boycott.

Representatives of western airlines said the boycott was diverting traffic to Eastern European capitals such as Prague or East Berlin. These cities are now being used as transit points between Moscow and the West.

Eastern European companies are gaining business, as are western airlines such as Air France and Austrian Airlines, which have defied the ban. Usually half empty, their flights are now fully booked for at least the next three days.

Soviet newspapers today published a commentary by the official news agency Tass accusing President Reagan of instigating the boycott in order to damage competing western airlines and disrupt "human contacts" between East and West. The commentary predicted that the boycott would fail.

When an American reporter telephoned Aeroflot today to ask about airline connections between Moscow and Washington, he was told: "We don't give that kind of information out over the phone--and particularly not now." Click.

An inquiry at the airport information desk about how to get from the capital of one superpower to the other met with a bemused grin and the remark: "Really, it would be much better if you tried to fly somewhere else. What about Havana?"