The likelihood of a pilot’s mental illness or suicidal feelings resulting in a crash in the U.S. is low; the Federal Aviation Administration maintains very strict guidelines for evaluating the mental health of aircrew. Under FAA rules, no one suffering from psychosis, severe personality disorder, manic-depressive illness or substance dependence can be issued the medical clearance to fly an airliner. Captains are required to renew their clearance every six months and first officers every year. Hundreds of people get refused every year.
That last sentence intrigues me. One would like to be a fly on the wall at a few of these proceedings.