Germanwings just got very ugly
A French prosecutor has accused the First Officer, Andreas Lubitz, of deliberately crashing Germanwings 9525 into the Alps. After the aircraft reached cruise altitude, the Captain left the cockpit. Germanwings apparently does not require two people to be in the cockpit during the absence of one pilot, so the First Officer was able to use the locking system to keep the Captain out for the remainder of the flight.
This explains why this could not have been an emergency descent for a depressurization; in that case the First Officer would have added two steps to the descent: a level off at 10,000 ft and a turn toward the nearest suitable runway, at Marseilles Provence International Airport. These did not happen; Germanwings 9525 continued straight into the mountains.