@kcockayne
The decision to impose a "2 in the cockpit at all times" policy is, though understandable, a thoroughly "knee jerk" reaction by authorities etc. who "have to be seen doing something" - no matter that it only complicates the situation & does not, necessarily , do anything to increase cockpit security.
It is, for the reason that it does not guarantee anything effective to avoid or overcome the problem, & for the fact that it was hastily (& unthinkingly) set up," Kneejerk".
It is unthinking because 1) it introduces another person to the cockpit (who might, in fact, be the perpetrator of this kind of action), 2)that person may be physically unable to overcome the remaining pilot, 3) that person is totally unqualified to recognise a problem caused by the remaining pilot's actions 4) &, unable to take corrective action, 5) make matters worse, 6) far from your simple explanation of being able to open the door for the returning pilot- be totally incapable of doing even that.
Indeed, I should imagine that such a person's presence & influence would be limited to a very slight deterrent to a pilot with such intent.
What do you really expect a lady stewardess, or a weakly built steward, or a lady pilot to physically be able to do to stop a more powerful (& technically capable) pilot from doing what he is suicidally bent on doing !?
The only way a third person in the cockpit would be reliably capable of stopping such actions would be if HE was a type rated, physically superior, pilot ( & then preferably if there were 2 of them - one to overcome the "suicidal pilot" & the other to correct his actions & fly the a/c).
Otherwise, forget it !
These sort of problems need calm, careful, reflective & exhaustive examination & problem solving to overcome. The whole history of the reaction to this terrible disaster & the piecemeal release of information by the investigators have complicated the very investigation that is taking place. It may even have jeopardised an eventual objective outcome ! (By releasing facts & info. ehich should not be in the public domain.
Certainly, I prefer the DLH Chief Executive's more measured approach & reaction - even if he may have appeared a little insensitive at times !
I appreciate the time you have taken to respond but I disagree with nearly all your objections. The central fact is that implementation of the "two persons" principle makes it far more difficult, by orders of magnitude, for a Lubitz inclined pilot to repeat that specific method of self-destruction. Dealing with your specific objections:
1. CC are given access to the FD anyway to deliver refreshments so the risk of one with evil intent is not much changed whether there to act as door opener or to deliver a cup of coffee.
2. Physically limited possibly but that also applies to captain v FO or vice versa, so no change there.
3. In any event, as I understand the sole pilot is supposed to be always at the controls and strapped in when the other has left FD. The CC only needs to be standing at the door ready to allow access and can call for assistance immediately if the remaining pilot makes any move to leave the controls.
4. I would agree that CC will often not be qualified to judge the remaining pilot's actions but that's not part of the requirement. The job is simply to guard the door and re-open it to the absent pilot.
5. How can CC standing at the door make matters worse?
6. As I understand, turning the handle from the inside over-rides any other lock so the CC at the door will ALWAYS be able to open the door.
Not one of your objection stands up to scrutiny. Moreover, if it is not an improvement, why was the "two persons" rule implemented by some regulators and some carriers even before last week. The answer is simple - it provides another layer of protection; one that quite probably would have prevented Lubitz from doing what he did, or at least not as easily.