Fainting pilot dived down

Pilots brave people. Their profession, especially at a test pilot, the profession is more dangerous than many others. Not in battle with the enemy, and in the process of peaceful everyday testing work perished such famous Soviet pilots, as Valery Chkalov, Valentin Serov, Polina Osipenko, a pioneer of the conquest of space, Yuri Gagarin.
First, such facts were connected only with technical defects of aircraft. But then it turned out that 60 % of accidents when performing aerobatics, especially after the release of the peak, is associated with blackouts are a pilot. It is not excluded that this was here.
The reason was the congestion experienced in such moments pilot. The output from the peak is a sharp slowdown in the position, feet first. The rate is reduced instantly on tens of meters per second. The acceleration of free falling bodies, due to the force of gravity is 9.8 m/S. acceleration in several times more than we experience significant overload: while acting causing this acceleration force, our weight is increasing in many times, how much this force more of the force of gravity. Falling from the 10th floor, the man at the moment of contact with the earth becomes a moment of weight in a few tons; arise injuries incompatible with life. When you exit the peak overload less, no injuries, but there may come a swoon. What it is called and what overload this danger?
The reason becomes clear if we consider that in our vessels flowing liquid internal environment - the blood. When 5-fold overload the blood also heavier in 5 times, and the heart can no longer raise it to the level of the brain. Brain cells are deprived of oxygen, and without it the mind of man can be stored no more than 5 seconds. This is the threshold of danger when overloaded, operating from the head to the feet (in aviation and cosmonautics it is called the positive overload). The threshold of this characterize two five - 5-fold overload within 5 seconds.