From a previous post of mine:
Apologies in advance if I have missed any vital pieces of information; I have tried to check the published information thoroughly before posting.
Some things are simply not adding up for me, particularly the 'evidence' supporting the theory that this was a malicious act by the FO. It seems that the FO has as good as been found guilty of murder without full evidence or any trial, however...
1. We are assured that the sound of the FO breathing (note: 'normally', not hyperventilating or panicked) is heard through to the end. Similarly, we're told that the Alt select can be heard being wound down, a seat being moved, and the door being opened and/or closed. Yet I haven't heard of any reports of the FD door being positively locked in the 'Lock' position, yet this should be clearly audible if these other faint sounds have been picked up. I cannot help feeling that this would be of sufficient importance to have been explicitly stated in the very detailed account offered by the French authorities of what they have heard. Some have questioned how breathing, described as gentle can be heard. I can assure readers that with digital signal processing techniques, including correlation and autocorrelation, signals significantly below the noise floor (ie completely drowned out by noise to the human ear) can be measured and heard, making the CVR a very rich source of audio clues that we wouldn't normally be able to hear. Few are aware that GPS operates by receiving signals sometimes 30dB or even 40dB below ambient noise levels (ie when massively swamped by noise which is many orders of magnitudes stronger than the actual GPS signal) by using this very technique.
2. Is the reported 'normal' breathing consistent with the alleged actions the FO is apparently guilty of doing? It gives the impression of being indicative of a relaxed, possibly incapacitated or even semi-conscious or unconscious person rather than someone knowing they are pointing at a mountain and about to die.
3. It has been assumed that the FO was conscious, if for no other reason than because he HAD to repeatedly re-lock the door after the 5 minute time-out. Have we had this explicitly stated by the authorities who know the facts or heard the CVR audio? If so, wouldn't this positive re-locking be clearly audible on the CVR as per my point above? However, the FO did not NEED to re-lock the door. If the Captain was preoccupied with banging on the door, as has been reported, it is entirely possible, even likely that he never made a (further) attempt to activate the access code as by this time his desperation to re-enter the FD would very likely be closing down options in his mind, to simply trying to smash his way in, just as we have been told. And wouldn't any attempt to re-enter the entry code be reported on as significant? A brief break in the door banging while a code is re-entered would be quite obvious on the CVR.
4. We are informed that the passengers were apparently unaware of the problem until the final seconds. By all accounts, the Captain made significant efforts to either gain the FO's attention, or indeed to break the door down. Are we really to believe that this all went completely unnoticed by the passengers?
Given these anomalies, I don't believe we have been told significant facts that have been revealed by the CVR. And it also seems very premature to judge the FO as totally guilty, as many have done so on this very forum, until the full facts are known. Maybe the media reports forced their hand, but I believe this partial revelation of CVR evidence combined with strong suggestion that the FO deliberately did this is not the way to handle such an important investigation as this.
Also, why would a landing briefing be given during the initial climb? This is a time to be on the lookout for any pressurisation problems etc, closely monitoring leveling off etc, certainly not distracting attention away from these essential monitoring roles with a landing briefing.
How could they have listened to the destination ATIS to determine runway in use and expected approach, specific local WX etc to be able to give a detailed and full brief by this stage of flight?
This reported 'landing briefing' doesn't make much sense - I think there was more to this specific briefing than has been mentioned by those who know, along with the actual discussion that gave rise to the reported change of mood of the FO.