A question for the A320 drivers: When descending through the Transition Level does the altimeter sub-scale setting automatically change from QNE to QNH or do you have to manually change it?
The reason I ask is that The Aviation Herald is reporting that: 'Radar data suggest the aircraft ... appeared to have leveled off at FL068 for one minute [prior to impact]'. The Grid Mora at the point the aircraft commenced descent is 6100. This suggests to me that the crew had set 7000 as a level off altitude for an emergency descent. 7000 is the Grid Mora at the descent point rounded up to the nearest 1000 and the difference between FL068/7000 could be due to the QNE/QNH difference.
This is consistent with the Rapid Depressurisation / Pilot Incapacitation scenario. The crew had enough time to wind down the altitude selector to 7000 and establish a descent, but subsequently became incapacitated before completing the rest of their emergency procedures. The aircraft descended on autopilot to 7000.
I can anticipate someone asking why didn't they set a higher altitude given that they were flying towards high terrain? Well at the point they descended they were very near the coast so high terrain was not an immediate issue. If depressurisation was the problem, then the immediate priorities are get on oxygen, establish comms with the other pilot and initiate an emergency descent. Setting the current MSA (6100 rounded up to 7000) is conceivable. I know, I know ... a lot of you will say just spin it down to anything, or anything but not below 10 000. But maybe in the stress of the moment 7000 was what was in their minds and that's what they first set. After the descent is established then you carry out the rest of the emergency descent procedures (declaring an emergency to ATC, adjusting the descent altitude, turning away from high terrain etc). Since none of these second phase procedures were performed, it would appear they've become incapacitated after the descent was initiated.