Fear of flying is at the center of the air traffic controllers' strike. The same fear kept 25 million Americans out of airplanes even before the strike. The Professional Air Traffic Controllers Organization (PATCO) has counted on fear to justify its wage demands. In their statements about continuing airline operation during the strike, PATCO representatives have talked of the danger of flying. When controllers talk about the stress of their jobs--and thus the need for higher salaries, shortened work week and early retirement --they return again to the theme of fear. Why, after all, is their job so stressful? Because, they say, "There is no margin for error."

As director of the Phobia Program of Washington, I have a professional interest in fear. As a physician who has worked for over a decade in public health, I have a special interest in safety. There are some curious aspects of the fear, and the resulting stress, about which PATCO speaks. The fear is a "what if" fear. Controllers feel stress by what could have happened or what almost happened. This "borrowing trouble" or "future thinking" is precisely the thinking that keeps phobic people disabled. For example, it is the fear that keeps many fearful fliers out of airplanes. It is a fear that is resistant to "facts." Even though only 13 people were killed last year in all U.S. commercial aviation, despite over 14,000 flights per day, the fearful flier can still argue that his flight could crash. The stress the controllers feel is the stress of protecting against the "what if."

To help put this in perspective, consider some other occupations. When an air traffic controller recalls, as one did recently, that he had a near miss several years ago in which two planes came within a quarter-mile of each other, this could be compared with the experience of a taxi driver's everyday experience with near misses. Contrast the complexity and stress and personal responsibility the air traffic controller experiences with the stress of the high school teacher in today's school environment, standing alone, before 30 teen-agers for six hours a day. Some may say that teachers don't risk death. Compare, then, an air traffic controller's fears and stress with the ordinary hospital doctor or nurse, or, for a more dramatic contrast, think of the emergency-room or the operating-room staff of a busy hospital. They see death itself, not the possibility of death, every day, and their margin of error is hardly more than that of the controllers.

Why do the air traffic controllers, and the public in general, feel so much stress compared with taxi drivers, high school teachers and emergency-room nurses? The answers are to be found in the public psychology of fear. There are three simple irrational principles that govern the perception of risk.

The first is whether the person feels he controls the risk. The person who drives a car feels "in control," as does the cigarette smoker, while the passenger on the plane or the person living down-wind from an industrial smoke stack feels "they" control his health risk.

The second principle is whether the risk involves one big event (such as an explosion or a plane crash) or little, separate occurrences. Thus, 130 people die each day in car crashes. This is not news and not scary. But 13 people a year killed in plane crashes is a big threat. Single big events are feared excessively, and this fear is often exaggerated by the media.

The third principle of risk assessment is familiarity. It is hard to fear the familiar and hard not to fear the unfamiliar. This principle underlies the successful new treatment of phobias-- supported exposure. It is easy to fear elevators if you stay out of them; it is hard to fear them if you ride elevators several times every day.

All this makes clear why the controllers feel themselves in a dangerous, stressful occupation and why the public agrees that these stresses warrant special benifits and salary for controllers.

A skeptic may argue that one does not need to walk across a freeway and get run over to know that the ''what if'' fear of crossing a heavy traffic is not purely a psychological problem. If we are to assess properly the risks we face in our lives, we must, at some point, compare one risk with another, and there must be some calculation of the danger based on what did happen rather than on what could have happened. Fears are as often underestimated on the basis of these irrational psychological factors as they are overestimated. Compare the lack of fear experienced by the nation's 50 million cigarette smokers (350,000 of whom will die this year because of their habit) to the fear of the controllers and the passengers in commercial airplanes.

The air traffic controllers consider themselves ''professionals.'' Part of that professional identity is the capacity to accept and manage the stress ad responsibility of the professional ideas in the psychology of work is stress management. Perhaps, as controllers are trained in the future, a new plan for stress reduction can be developed -- one that helps the controllers themselves have a more useful perspective on their work.

Airplanes do crash and controllers are an important link in the safety chain that protects the flying public. However, there has been a distortion in the sense of risk and the relative stress of this occupation, which is now seriously confusing the debate. Not only is the public suffering as a result of these irrational fears, but, I suspect, so are the controllers.