Look, you seem to be missing my point which is that the whole idea of locking the cockpit door is flawed for the very reasons that you state - that access or exit is required from time to time - understandably. A solution to serving food / drinks could be a lockable hatch in the cockpit door - a solution to the 'comfort breaks' situation is more difficult but could be solved by the secondary 'air lock' door as suggested by PT6A, though this might be difficult to physically install. I'm not having a go at you fine folks - I just want everyone to fly in safety and as I saw something that I thought compromised that, thought it appropriate to raise the issue.