(CNN)It is now generally accepted that Germanwings first officer Andreas Lubitz did indeed lock his captain out of the cockpit, put their airplane into a steep descent, and then sit back and wait calmly for the end to arrive. He did it with premeditation, having discarded a doctor's note that would have excused him from work that day. He  joins the short and infamous list of airline pilots, a handful over the past two decades, who have used their airplanes to combine suicide with mass murder. Why is this thought at once so fascinating and so horrifying? It is because of the incompatibility between what we want to believe about flying and what we now see. Air travel presents itself as a highly controlled, stringently professional activity, stripped of every unpredictable element. Flight crews wear military-style uniforms not because they could not fly equally well in street clothes, but because uniforms convey to passengers a subliminal suggestion that they are of a different breed, as far from ordinary folk as a world-class athlete is from a duffer. Not only are pilots smarter and better-trained than ordinary people, those stripes and caps say, but they also must be less forgetful than we, less distractible, better rested, not prone to irritability or sadness or smoldering resentments. Like soldiers, they must be just a little bit robotic, efficient, brave and purified of the trash that infests the souls of common humans. Because they have earned their stripes, we feel safe -- even when it seems impossible for us to understand, or apparently for anyone to explain, what keeps those huge metal contraptions up in the air. The truth, as the voluminous history of airplane accidents reveals, is that pilots are not different from other people. They can be careless, lazy, inattentive and reckless. They can drink too much. When pilots talk among themselves,  the mistakes, the close calls, the disasters averted by sheer luck are favorite topics. But if pilots slip up in little ways from time to time, the sweeping drama of aviation, in which they are the actors and we the audience, eclipses their faults. Besides, most flying is routine -- hours of boredom, the cliché goes, punctuated by moments of sheer terror. The glitches have long since been ironed out, and the airplanes are so wonderfully engineered that they usually protect even the worst pilot from himself. Nor are pilots of a higher moral type than the rest of us. Despite the pieties they occasionally utter, pilots do not consciously shoulder the burden of hundreds of lives or feel more responsible for a full airplane than for an empty one. Pilots, by and large, are proud. They identify with the airplane; it is an extension and enlargement of the self, and the pilot feels the same motive to deliver it safely to its destination as you feel when driving a car on a crowded freeway. A pilot values a smooth landing because it demonstrates skill, not because the people in back are still alive. The greatest guarantee you have that your pilot is devoted to your safety is the fact that he or she is in the airplane with you. So we should not be overly astonished if from time to time a pilot does something completely incompatible with our confidence. Pilots are drawn from the diverse pool of human types. The human mind is the blackest of boxes; no one, neither colleague nor psychologist, can reliably peer inside it. Desperate, cataclysmic acts occur almost daily all over the world; why should they not occur, once in a long while, in cockpits? Perhaps, with time, we will understand better who Andreas Lubitz was and what he did. Today, we still know very little.
Experts suspect first officer Andreas Lubitz locked pilot out of the cockpit of plane . Peter Garrison: Pilots don't exist on different moral plane than the rest of us, and the human mind is the blackest of boxes .