Los Angeles: Jim Vanderploeg is a professor of Aerospace Medicine at the University of Texas Medical Branch in Galveston.

As part of his job, he works with the Federal Aviation Authority (FAA) to evaluate airline pilots who are being treated for depression or substance abuse and who want to get back into flying.

He describes how the mental health of pilots is monitored and tested in the United States.

What are the red flags you look for when you evaluate a pilot?

When a pilot comes to me they have already been through treatment of some sort or another through their company airline or on their own and are at a point where they want to get their medical certification back.

When you are dealing with things like anxiety or depression the typical red flags are if they are not sleeping well, a change in eating — either more or less — and if there are any family problems developing with their kids or spouse. Those are life stressors that could indicate there are some unresolved and undiagnosed mental health issues going on.

How often are pilots psychologically evaluated?

The frequency of the medical evaluations depends on age. If you are under 40 it occurs once a year. Over 40 it occurs every six months. That includes a review of a person’s medical history, both physical and mental, and a hands-on physical exam.

There is not a formal psychological test like you might do if you went to see a psychologist, but what is included is an interview by the doctor of the pilot asking about sleep changes or family issues they have to deal with.

Have you ever had to decide a pilot was not fit to fly?

Yes, I have, both for physical problems that don’t meet the FAA’s standards or for concerns about psychological problems. The way that is typically handled is we say we need to do further investigation. They may need to see a psychiatrist or go through more formal psychological testing. Then it is decided whether they made the certification requirements.

Besides an annual or twice-yearly check-up with a doctor, what other ways are the mental health of pilots evaluated in the US?

Pilots are evaluated in a variety of ways beyond their medical exam. When they are working for an airline, they have to do refresher training in a simulator where a bunch of high-risk situations are thrown at them — either terrible weather, or they lose an engine. It is a pretty high-stress environment. The airlines observe their performance, but also their reaction to those stressful situations.

Pilots are also required to ground themselves if they are aware of a change in their physical or mental status. They know what the qualification requirements are. It’s a self-identifying system and it’s not perfect, but pilots for the most part want to do the right thing and are good about not putting themselves and their customers in peril.

We are still learning about what might have motivated Andreas Lubitz to crash a plane into a mountain, but from what you’ve heard and read, do you think any warning signs may have been missed?

I really can’t comment on him specifically; the information I have is only what is being reported in the news media. However, if pilots choose to hide or not disclose things they are dealing with, it can be very difficult to observe those problems externally.

Carsten Spohr, chief executive of Lufthansa, suggested that what Lubitz allegedly did cannot be classified as suicide. “If a person takes 149 other people to their deaths with him, there is another word than suicide,” he said. What are your thoughts on that?

It’s hard for us who are mentally healthy to imagine that anyone who would wish to commit suicide would want to take 150 people along with them. We can’t fathom that, but mental illness, if that is indeed what occurred in this case, can be a devastating illness and people don’t do rational things.

Does this tragedy make you more scared to fly in the future?

When one looks across the history of aircraft accidents it is extremely rare that the cause of that accident has been due to a medical, physical or mental problem. If that is, indeed, what it turns out to be in this case, it is an extremely unlikely event.

The system in place for refresher training and evaluation has worked very, very well for us over the years and has been effective at identifying if there are problems and dealing with them before they become an accident.

There is no system that is 100 per cent perfect 100 per cent of the time. I fly a lot, and I have no more uneasiness about getting on a plane Sunday night than I did last week.

— LAT