The tragic crash of a jetliner in the French Alps has spotlighted the potential problem of airline pilot depression.

German pilot Andreas Lubitz intentionally crashed a Germanwings plane, killing all 150 aboard after apparently being treated for mental illness, authorities say.

Depression is one of the most common mental illnesses, with studies showing that about 9 percent of American adults suffer from the condition, according to the Centers for Disease Control.

Since there are 104,000 commercial and airline pilots in the U.S., that would mean there could potentially be some 9,200 pilots with depression, assuming they suffer the illness at the same rate as other American adults.

With such statistics, it is very likely there are pilots flying today who are dealing with depression, a factor that could put passengers at risk, according to Angelos Halaris, M.D., a Loyola University Medical Center psychiatrist who specializes in depression treatment.

Although pilots are routinely screened for physical and mental problems, Lubitz apparently successfully hid his condition from his employer, according to reports.

“People who are depressed can hide it successfully,” said Dr. Halaris, who heads Loyola’s psychiatry department. “They can fake a normal mood, or tear up a letter saying they are not fit for duty, especially if they are so driven or take it as a personal insult or embarrassment.”

According to crash investigators, the pilot had taken a break from flight training in 2009 for depression and anxiety treatment, which should have been a red flag, said Dr. Halaris.

Such lax oversight points to problems not only in other countries, but in the U.S. as well, Dr. Halaris told Newsmax Health.

“One area in we have lagged is our ability to do a good job assessing individuals in terms of putting them in charge of a plane, train, or even surgeons -- any job in which they have control of other people’s lives. We need to get serious about it.”

Dr. Halaris has treated thousands of people with depression over the years, and said he makes such a recommendation with reluctance. But in the case of pilots, this is justified, he believes.

“If the person fails, we are left with a disaster,” he said.

Such a prohibition should apply even to those people successfully controlling their depression with medication, said Dr. Halaris.

“People on medication can stop taking medication, and unfortunately, with depression this happens all the time. If people stop taking it, they can go into a massive relapse,” he said.

“We don’t know if this is what happened in the case of the German pilot, but if it was, it took the lives of 150 people.”

Dr. Halaris said he was taking his stance to prohibit depression patients from being pilots reluctantly because, “I am the last person to support any discrimination with people with a psychiatric disorder.”