There is certainly one constructive measure which will result from the tragic destruction of KAL Flight 7 over Sakhalin Island on Aug. 31. Governments, airlines, and pilots organizations will demand and undoubtedly obtain better means of informing pilots flying near Soviet frontiers of their actual locations.
Existing evidence would indicate that had the pilot of Flight 7 known he was off course he would have taken himself safely out of Soviet airspace long before he ever reached Sakhalin Island. The chances are that he had no idea that he was in danger until his plane was actually struck by a Soviet missile.
The plain fact, and not a new one, is that the Soviets are extra-sensitive about their airspace and inclined when something intrudes into it to shoot first and think about it later. No Soviet air defense officer is likely to be court-martialed for shooting at a foreign aircraft. He could even be shot for allowing a foreign plane to enter, and then make good its escape. There are unofficial reports that this has happened to more than one Soviet officer.
There is no serious chance that the Soviets can be persuaded to adopt more civilized practices about commercial aircraft which may stray off course. Most Soviet citizens probably believe that any intruder is a spy in disguise. Russians have long been like that. They are not likely to change suddenly just because the civilized world is shocked and angry over what they did on Aug. 31.
Their concern is for the security of their air defenses, not for the safety of foreign passengers flying near their frontiers.
So, the only protection against a repetition is to make sure that commercial airliners do not in the future stray unintentionally into Soviet airspace. That in turn means new devices which will make it possible to determine any off-course event and warn the pilot at once of his danger.
Beyond that, what are the other long-term consequences?
Of course it will now be easier for President Reagan to get his military budget through Congress, including funding for the MX missile.
Western European governments will probably find it politically easier to ride out the series of ''anti-deployment'' demonstrations scheduled all over Western Europe this fall as the new American weapons arrive. The fate of Flight 7 has removed any last doubt about the deployment. It will take place.
Another probable result which will be welcome in Washington is an improved climate in Japan for an increase in the size and range of Japanese defense forces.
But on the other side of the coin, President Reagan is likely to have a more difficult time putting a new arms limitation agreement through the Congress, if he gets one.
Present Washington planning calls for such an agreement sometime in 1984 in time to adjust Mr. Reagan's public image in a more ''peace-loving'' direction.
The assumption is that once the new Pershing and cruise missiles are actually in place and the Soviets know that they and the ''peace marchers'' of Western Europe have failed to prevent the deployment, the Soviets will then be ready to go ahead with a realistic arms control agreement.
If this assumption proves to be correct, and if an agreement is then reached in the spring, Mr. Reagan will have strong political reasons to want to push it through the Senate before election day.
But, his own right-wing constituency is up in arms already over his failure to do anything solid to punish the Soviets for shooting down Flight 7. He has not revived the grain embargo. He has not forbidden all imports of Soviet goods. He has not broken off arms control talks. He has in fact done nothing which in any serious way punishes the Soviets for what they did; he has only called them names.
The conservativies will certainly oppose any arms control agreement Mr. Reagan presents to the Senate. They will oppose it regardless of its terms on the ground that it is trafficking with the Soviets. They want no traffic of any kind with the Soviets. They will give Mr. Reagan a hard time on arms control.
As for other possible consequences: The present airline boycott is not complete. And most of the lines which are not today flying to Moscow will be flying again in another week or so. The Canadians did a 30-day ban, but most went only for 14 days. American travel agencies are already lobbying for a reopening of Soviet Aeroflot offices in the US. The agencies say they are losing money to European competitors.
Some Washingtonians think there will be a chill in Soviet-American relations well into next year. The chances are that by next year the tragedy of Flight 7 will belong to history.