"It most likely couldn't be avoided" — 3 pilots on the Germanwings crash

Germanwings Flight 4U9525 crashed into the French Alps last week, killing all 150 people on board. In the days since the crash, French prosecutors have revealed a frightening theory for what happened in the plane's final minutes in the air: the co-pilot, Andreas Lubitz, may have deliberately crashed the plane while the pilot was locked out of the cockpit.

"The guy outside is knocking lightly on the door, and there is no answer," a senior French military official told the New York Times, citing information from the plane's voice recorder. "And then he hits the door stronger, and no answer. There is never an answer." Later, the same investigator said, "You can hear he is trying to smash the door down."

Plane crashes are extremely rare, and intentional crashes are even rarer. Still, airline pilots confront unique challenges as they carry out their difficult jobs — jobs where mistakes could endanger the lives of scores of people. On a recent Quora thread, several pilots described the stresses they face on the job — and explained why they think the Germanwings tragedy likely couldn't have been prevented, even with stricter mental health screenings. Here are some highlights from their answers:

Pilots need to suppress their emotions — and problems arise when they can't

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Tim Hibbetts, naval aviator, airline pilot, aerospace engineering major: There's a little bin for everything, from flying to anniversary dates (a smaller bin, easily closed, evidently). If you don't need that bin to fly, you close it. Argument with the missus? Shut that thing and push it aside. Got cut off in traffic? Daughter not feeling well? Lost your dog? Watched Game of Thrones? Shove all that frustration way back in the corner and shut it away in the dark. Once you're done defying gravity and cheating death, deal with it, but here and now isn't the place or time. You're saying you can't keep that lid shut tight? Don't fly. If your head isn't in the right place to wield a hundred tons of steel and fire, then you shouldn't be pulling a yoke.

Tom Farrier, retired US Air Force command pilot; current aviation safety contractor for the government: A common thread among many who fly for a living seems to be an ability to focus on the task at hand while setting aside other aspects of their lives (relationship issues, money concerns, etc.). Flying tends to be an immersive activity demanding a great deal of attention to do properly and safely.

In my experience, "coping" becomes a problem for pilots, air traffic controllers, and similarly highly skilled professionals with challenging, task-driven jobs when the various compartments into which they like to keep the different parts of their lives (daily personal routine, family life, work performance) start to leak into each other.

Being a pilot is extremely demanding — and often low-paying

Tom Farrier: Lots of pilot jobs these days tend to be quite low-paying at the entry level, especially when the physical demands of long hours and constant exposure to onboard aircraft environment (dry, lower-pressure air, etc.) are taken into consideration. They also often require pilots to go out-of-pocket to get adequate rest; they don't necessarily provide opportunities for rest or meal breaks during the day; and they frequently drive newer pilots to travel significant distances to start and end their work cycles, simply because the cost of living of major airline markets often is out of newer pilots' reach.

It can be difficult to speak up if you're concerned about your co-pilot

Tim Hibbetts: Another potential source of stress is between the crew members. If you think speaking up is going to get you chewed out, there might be a hesitation, and that lapse may be all that's needed to court disaster. As a wise captain once instructed me in a pre-flight brief, "If I'm messing up, tell me. My skin is thicker than my wallet." On the obverse, if your fellow pilot is displaying erratic behavior, you now have grounds to question his fitness to fly that day.

Tom Farrier: Pilots are not always good at introspection, so they don't always catch themselves losing focus. Their supervisors also tend to be pilots, and may find it difficult to approach another about performance or behavioral problems they might observe that don't have a direct bearing on how well an aircraft is guided from Point A to Point B on a daily basis.

(Shutterstock)

Most pilots are mentally stable

Tom Farrier: I've found people who fly tend to love life — whether naturally an introvert or an extrovert, flying is a pleasurable activity that offers the opportunity for self-expression, stress relief, or just the chance to be really good at something many people can't do.

Monitoring every pilot for mental health issues is probably impractical

Tom Farrier: The bottom line is that stress is stress, and humans are humans. Different jobs bring different stressors; the aviation industry as a whole has a lot of experience with its stressors, and has institutionalized a number of protocols for trying to relieve them. Can more be done? Sure. Is the monitoring of individual pilots optimum in every company? Probably not, but there's little agreement on precisely what symptoms or markers should be considered warning signs of a need for intervention.

It'd probably be impractical to even consider much beyond what's already been recognized as necessary and appropriate at an industry level.

Kåre Lohse, flying out of Hong Kong: Could it have been avoided? It's easy to be a Monday morning quarterback. No, it most likely couldn't be avoided.

Every day, we trust our lives and health left, right, and center. From the food you eat for breakfast to the water you drink from the tap (or bottles?), the bus that takes you to work (or taxi/friend/family member). You could be shot by some criminal, sick from medicine, and the list goes on.