When pilots choose to crash, shouldn’t there be some way to stop them?

It is extremely rare, especially in commercial aviation, but on occasion a pilot chooses to die at the controls.

And when that happens it stirs a cloud of questions, especially: How could that possibly occur in an era when security has become so paramount?

American flights do enforce some safeguards not always present overseas, where the worst incidents have occurred.

Still, at least one expert says the crash of Germanwings Flight 9525, which investigators believe may have been intentional, should prompt more aviation medical examiners in this country to probe deeper into the psychological state of pilots.

John Hastings is a Tulsa, Okla., neurologist who is among the people charged with identifying pilots on the verge. He is a senior aviation medical examiner, part of a large fraternity of American physicians who tend to be pilots themselves.

The Federal Aviation Administration requires U.S. airline pilots to undergo a physical exam at least once a year — twice if they’re age 40 or older.

Hastings, who has worked with pilots since 1976, said Thursday that theoretically, the examiner should at some point ask the pilot how he’s doing, whether he has any troubles at home, or any at work.

“To my way of thinking,” he said, “looking that pilot in the eye and asking those questions is the most important reason for doing the physical.

“But how much time is typically spent examining a pilot’s emotional health? Very little. In my opinion, too little.”

Still, some rules for monitoring the mental health of aircraft crews are stricter in the United States than in many other countries, aviation groups say.

For example, the FAA prohibits an airline pilot from being alone in the cockpit during flight, as was the case when Flight 9525 descended and crashed into the French Alps.

At least two crew members must be in the cockpit at all times on U.S. flights.

“If one pilot needs to use the restroom, you’ll see a flight attendant step into the cockpit” to accompany the pilot at the controls, said Steve Hedges, spokesman for the Aircraft Owners and Pilots Association.

The Air Line Pilots Association International issued a statement Thursday stressing the two-person rule and the “rigorous screening” of U.S. and Canadian airline pilots prior to being hired.

In addition to the required physical exams, the pilots’ union noted, “all flight and cabin crewmembers monitor and evaluate each other while on duty, and procedures, processes and programs exist to respond should a concern arise.”

It added about the German flight: “We urge the public to refrain from speculating about what may have transpired and allow a thorough investigation to be undertaken.”\

The co-pilot of the Germanwings jet may have had a brief, untreated bout of depression while undergoing pilot training, according to German news accounts.

Lufthansa, the operator of the low-cost Germanwings airline, said that the co-pilot, Andreas Lubitz, had taken a break during his training but had been thoroughly tested and cleared upon his return, completed his training and was considered “100 percent fit and ready to fly.”

But the mother of one of his former classmates told the German newspaper Frankfurter Allgemeine that Lubitz had confessed to her daughter a few years ago that his timeout during training was because of “a burnout, a depression.”

Still, the co-pilot was well thought of, and people who knew him were at a loss to explain what would have caused him to decide to kill all those aboard.

“People who commit suicide usually do so alone. When you do it with 150 people behind you it’s not suicide,” said the French prosecutor leading the investigation, Brice Robin. “That is why I am not using this word. I don’t call it a suicide.”

Robin said that Lubitz had no known connection to terrorism and that there is no known motive for his apparent actions.

Findings and speculation of airline pilots intentionally crashing planes date back decades. Incidents cited by the Aviation Safety Network include the possibility that a suicidal pilot was flying Malaysia Airlines Flight 370 when it went missing last year over the Indian Ocean.

Other cases:

▪ In 2013 LAM Flight 470 entered a rapid descent and crashed in Namibia, killing 33. Results of a preliminary investigation indicate the captain set controls for the plane to hit the ground while the first officer was away from the flight deck.

▪ In 1999 Egypt Air 990 bound for Cairo plunged into the Atlantic Ocean 30 minutes after taking off from New York. During the plane’s tailspin, pilot Gamal al-Batoui muttered several times “I rely on God,” an Arabic phrase traditionally spoken moments before death. All 217 passengers and crew died.

▪ Two years earlier, a U.S. investigation of a Silk Air Boeing 737 that went down in Indonesia, killing the crew and nearly 100 passengers, determined that the crash was deliberate. The Indonesian government found nothing conclusive to support that finding.

▪ In 1994 the captain of a Moroccan airline disconnected the autopilot and crashed a turboprop carrying 44 people into a mountainside. He reportedly had a troubled love life.

This story was originally published March 26, 2015 at 6:53 PM with the headline "When pilots choose to crash, shouldn’t there be some way to stop them?."