Eventually the National Transportation Safety Board (NTSB) will tell us just how high Flight 90 got; how swiftly it flew; how much it weighed; which turbines were thrusting on impact; how each passenger died or survived. Then it will tell us the "probable cause" of the accident.

This is a kind of moral proclamation. Pure science limits itself to the presumption that a given set of circumstances can produce only one result. Which of the circumstances ought to have been different on Flight 90 is a question of aviation morals.

Morals are remarkably flexible. If our property values are hurt by overflying aircraft, we can blame short runways at National. If our union members are airline pilots, we can blame miserly training or shoddy equipment. If we manufacture avionics, we can point to inadequate instrumentation. The beauty of morals is that we can all be right.

Likewise, the official "probable cause" on which the NTSB settles will reflect its notion of the way things ought to be. The big difference is that the NTSB has no obvious axes to grind. And according to the board, the principal cause of two-thirds of fatal airline accidents is the captain. NTSB spokesman Brad Dunbar told me Thursday that the "two- thirds" number has proven "uncanny" in its predictability over the years.

How to deal with "human factors" is a tough question. They're already being dodged on Flight 90. Television commentators ask their experts why the captain was "allowed" to take off in such poor visibility, with ice on the airframe, with slush on the runway, and so on.

Flight 90 may prove to be the exception. American's DC10 crash in Chicago couldn't have been averted by a mortal pilot. Most competent captains would have done exactly what Eastern 66's captain did when he crashed at JFK. But exceptions don't happen that often. That's what makes them exceptions.

In sterner days, the pilot would have been held responsible, albeit posthumously. That would have been the end of it. But the public likes specific solutions to specific crashes. They want to hear that Flight 90 crashed because of A, B and C, and now we've taken steps X, Y and Z so that it will never happen again.

We can't check the wiring diagrams on a dead captain. So we do the next best thing. We make a regulation forbidding whatever preceded the crash. Or we require a new instrument that tells us when the 14th Street Bridge is near. Or we hire a thousand government "ice inspectors" who must sign off on every flight. Or we require snow plow operators to be licensed. In all cases, we rewrite the airline's operations manual.

We buy a lot of safety in the process. But mostly we just buy peace of mind for the flying public.

We have done something else too. We've made more people responsible for each flight. And the more people who are responsible, the less responsible each is. We don't like to sully our high-tech games like accident analysis (or accident investigation) with "human factors." So we've dissipated the responsibility of the captain to satisfy the flying public, and in so doing, we've endangered the flying public.

If "captain failure" is really responsible for two-thirds of fatal crashes, then why don't we give captains the same scrutiny we give radios, which account for almost no fatal crashes?

Why is a captain's proficiency checked only two or three times a year?

Why are aeromedical examinations kept confidential by the FAA and by most airlines?

Why does the FAA honor a pact with pilots that cockpit voice recorders and flight data recorders will never be pulled out of aircraft to police--or even monitor--pilot performance?

Why was it December 1980 before the NTSB hired its first psychologist? And why does it still have only one?

Why, in its report on Flight 90, will the NTSB most likely fail to tell us what kind of a man the captain really was? We're going to find out whether his thumbs were broken on impact and whether there was scar tissue in his heart, but not whether he was a jumpy, conscientious fellow or whether he was steel- nerved and cavalier.

Airline pilots mostly disagree with me. But they don't say those factors are irrelevant. They say captains deserve privacy.

That's not true. An airline pilot, in the cockpit, is the link on which the whole system depends. He deserves all the scrutiny we'd give an altimeter, a radio or a wing spar. After all, the Federal Air Regulations, in ceremonial--almost mystical--words, have proclaimed him "the final authority."