Germany has a special unit commando called KSK (Kommando Spezialkrafte).
To be selected, a candidate has to go through rigorous training, designed to push someone to their limits and far beyond.
Similarly to Navy Seals, they have their own brand of Hell Week.
One particular exercise, involves to walk uphill for several hours, after being sleep deprived, tired and hungry.
To make things worst, each candidate is gifted with a log of approximately 30 kilograms.
If the log accidentally falls, you have one chance only, to pick it up immediately and continue.
If, however, the log is thrown on the ground deliberately (out of anger, frustration or similar), you are removed from the course on the spot.
The reason for this, is no matter how much stress you are under, you should never let your emotions decide for you.
These guys work with hostage situations, terrorists and so on. Understandably, the room for error is tight.
Here comes the scary part.
This is Andreas Lubitz, one of the most hated pilots in the history of aviation.
On the 24th of March 2015, Mr Lubitz committed suicide by locking the Captain of Germanwings Flight 9525 out of the cockpit and then diving the plane with its 150 passengers into the French Alps.
In 2007, he graduated from high school and was accepted as a Lufthansa trainee the following year, enrolling at the company's training school in Bremen.
Lubitz had a break in training about six years prior, lasting several months, according to Lufthansa CEO Carsten Spohr.
He suffered a serious depressive episode during his treatment and went on to receive treatment for a year and a half. During that time, he considered suicide but was eventually declared healthy.
If at this point the connection between the two facts remains unclear, let me elaborate.
Special Forces Soldiers, work in small groups where, worst case scenario, could get only a few of other soldiers killed: soldiers who voluntarily chose a risky profession, fully aware of the consequences.
Still, the bar is set extremely high. Drop the log, you are unfit to continue.
On the other hand, we have a man responsible for 150+ souls (whose only fault, was to have chosen the wrong holiday destination) allowed to fly after a diagnose of depression and suicidal tendencies.
On top of all this, today’s pilots are already under extreme financial and psychological pressure, work very long hours and their salary it is often insufficient to pay the debts accrued for their training.
There are plenty of reasons to be depressed as a pilot, and terrified as a passenger.
EDIT: thanks everyone for the upvotes. The information about pilots working conditions was brought to my attention while listening to a podcast from a former Alitalia Captain, Antonio Chialastri, an expert in human factor in aviation and author of several books on air safety.