It is reported that the co-pilot Andreas Lubitz had rehearsed putting the aircraft into a controlled descent which was before the crash into the French Alps. This report which is from the BEA, is currently basing the analysis off of the flight data recorder and cockpit voice recorder. With this data, they are certain that there were many altitude selections towards 100 feet that were recorded during the descent while the co-pilot was all alone in the cockpit. The captain had only left the co-pilot alone for less than five minutes when this all went down. On the flight home from to Spain to Dusseldorf, the co-pilot is now blamed for slamming the Germanwings Flight into the French Alps. He killed all 150 people on board. Lubitz suffered from depression and while on the flight he refused to let the captain re-enter the cockpit. With this incident happening, many people want to be able to monitor the mental health of pilots. While the co-pilot was alone in the flight deck, he was asked to bring the plane down to a lower altitude. He chose to decrease the altitude to 100 feet for three seconds, increase back to 49,000 feet and then finally go back to 35,000 feet. The co-pilot kept changing the altitude several times. Since the co-pilot was asked to descend, the air traffic controllers would never notice his rehearsal of different altitude settings. They just assumed he was testing the parameters of the aircraft's systems. It can be considered that he was testing the computer system to see when the alarm bell might go off. During the descent, air traffic controllers were trying to call the flight crew 11 times even on three different frequencies but they didn't answers. The captain was trying desperately to get back into the cock pit. You could all hear this in the recorder and then all of a sudden the air plane crashed.
Smith-Spark, Laura. "Report: Germanwings Co-pilot Practiced Crash Descent - CNN.com." CNN. Cable News Network, 6 May 2015. Web. 6 May 2015.