Originally Posted by
mustafagander
To me this looks like a solution desperately seeking a problem.
Do we have any security problems with the current system? I mean real threats not possibilities.
The underlying assumption must be there is some residual risk inherent in the single door solution. As, to my knowledge, there has never been a breach of the current solution, that risk is only a perceived risk and one may estimate that it is very low. The problem with designing any mechanism to remove very small residual risks is you have to be extremely sure you are not adding or increasing other risks because even a small increase in such risks - and in this case I mean blocking legitimate access to the flight deck as a real and demonstrated danger - would completely outweigh the risk you are trying to remove. Basic safety arguments based on the relative probabilities can demonstrate this very well and I would be intrigued to see the FAA's numbers in this regard.
If this second door is implemented, there would need to be some extremely strict operational rules in force to avoid the "unforeseen consequences". One of those rules would certainly be that, during flight, no member of the flight crew could, under any circumstance whatsoever, pass through or beyond that second door. So yes, loo access would need to be designed accordingly.