The tragic crash of Germanwings Flight 9525 has aviation experts trying to figure out what happened. While the French government is treating the crash as an accident, the possibility of terrorism has not been formally ruled out. What is known is that the aircraft cruising at altitude began an 8 minute descent staying on course until it crashed into the mountains. There was no distress signal and no call from the pilots.
There are four possible causes of this kind of plane crash. Three of the four causes involve depressurization.
The first cause is a catastrophic structural failure. This seems to be the least likely scenario because it is highly unlikely a plane would stay on course and descend so slowly if something terrible happened to the aircraft’s structural integrity, such as a wing failure or a lost rudder. The plane would in most circumstances have deviated from its course, and plunged down to the ground. The pilots would probably have had time to send a distress call.
The second cause is an external catastrophic event. This event would be a plane that was hit by an object of some kind, causing depressurization. If the plane was hit in the forward section or in the cockpit, there would not have been time for any emergency call. Since the weather at the time was fairly clear, such an object could be either a meteorite or some other kind of space junk that hit the airplane (a one in a billion chance) or the airplane was hit by another airplane or by a missile. At this time there is absolutely no evidence either for a “natural” or man-made cause of this kind. It is possible the recovered, but damaged, flight voice recorder may tell us something. But it is just as likely we may not learn anything.
One of the theories being put about is that there could have been a windshield (windscreen) failure. There is one significant example of a windshield failure where maintenance workers installed the glass with the wrong type bolts. While this theory could account for rapid depressurization and disabling one of the pilots, it is hard to account for knocking them both out. In any case there is not information as yet that would lead to a windscreen failure, and the altitude of the plane would mitigate against any possibility of a bird strike.
The third cause is an internal catastrophic event such as a debris from a disintegrating engine, an explosion caused by the airplane’s batteries, or a bomb. Neither an engine failure, a bomb or an explosion has been ruled in or out. An engine failure could create debris that might penetrate the aircraft skin and lead to depressurization. While pilots have little time to react, there is enough to send a distress call. It does not seem that an exploded engine was the cause. The possibility of a bomb is an entirely different matter, depending on where the bomb was placed. If it was in the passenger compartment or in storage, the plane probably would not have stayed on course, the pilots would have been able to react and try and control the plane. This does not mean there was not an explosion and it could be that the voice recorder will indicate that. The explosion of a battery also can cause a catastrophic event and might have shut down the electrical system. Battery explosions are a known risk. But a battery explosion almost certainly would not have stopped passengers from making cell phone calls.
The fourth case is a terrorist attack where the cockpit is immediately overwhelmed and the plane headed to the ground, in other words a suicide terrorist event. The voice recorder will probably tell us that such an event took place. It is surprising that the French view, which has not been disputed, is this was not a terrorist suicide attack. The French authorities have not assigned their counter-terrorist investigators to Flight 9525. It is important to note that there have been no claims by terrorist organizations that they were behind the destruction of Flight 9525.
Airbus aircraft are designed differently from Boeing passenger airplanes. In Boeing aircraft, the pilot can override automatic controls. In the Airbus design this is much more difficult because the software that controls the aircraft does not allow deviation from safe maneuvers. There are reports that Airbus aircraft have been difficult to manage under extreme conditions. Whether this applies to Flight 9525 is impossible to determine, since presently we have no evidence that the pilots tried to control the plane and no evidence whatever that the plane ever went off course. This means there was nothing to override and the pilots were not in positive control of the aircraft in any event.
The best we can say now is that some event rendered it impossible for the pilots to communicate to aircraft controllers or send any emergency message or to steer the aircraft to some kind of safe landing. It would also seem that the passengers had little realization the plane was in trouble because there are no known cellular phone calls. While the area was remote, there probably were cellphone towers capable of receiving calls. As the plane descended gradually passengers may not have been aware of any event in the cockpit, but this seems very unlikely. In fact, unless there were no cell towers anywhere near where the aircraft was flying, this is an even bigger mystery than the cockpit failing to send a warning.
The flight data recorder case has been found but not the innards. The search is on to see if any of the internal parts can be found. The aircraft is in many small pieces strewn over a fairly wide area. It will take time and some good luck to find the remains of the recorder’s components.
Airplanes do not just fall out of the sky. Generally speaking flight at cruising altitude is generally the safest part of flying; more accidents occur on take off and landing. This is why most of the experts are strongly of the opinion there was cabin and cockpit depressurization and that no one had control of the airplane. A slumped over pilot pushing the aircraft into a descent is probably what happened. The question is what caused the pilots to black out and the plane to go down. Or even if the pilot deliberately crashed the plane, also a possibility.
The latest information is that one of the pilots, probably the captain, had left the cockpit and could not get back in. The door was locked, as it is supposed to be, and the other pilot did not open it. The reason why remains a mystery. Had something happened in the cockpit to incapacitate the copilot? A stroke, heart attack, black out? Was it a suicide event?
Under Airbus procedures there is a code that the chief stewardess can use to unlock the door. However the pilot or co-pilot can override this attempt. This tells us that the co-pilot in the cockpit had to be alive and capable and prevented the pilot from entering.
The latest news is dramatic. The Marseille prosecutor said the plane was crashed deliberately by the co-pilot. “The German citizen, left in sole control of the Airbus A320 after the captain left the cockpit, refused to re-open the door and pressed a button that sent the jet into its fatal descent, the prosecutor told a news conference carried on live television.”