@Andy_S looks like someone on here has deleted my suggestion. What a
Only the Pilot leaving the cockpit know's the code he has entered. It's something he must remember whilst using the facilities. It can't be that hard can it? You are telling me that the Pilot leaving the cockpit is going to be interrogated by terrorists at that instance and force a code from him? I highly doubt it.
We are using an outdated system post-9/11 that is fictitious. It needs changing, clearly. If MAS370 is found out to be similar to this incident, then we know we have a few rouge pilots possibly still flying around the world ready to strike. In the digital age, you'd think something better than a keypad could be used for entry/exit of a cockpit door. Entering a one-time only code a bit like RSA SecurID into a NEW exit panel for the cockpit, and being able to use this to gain entry would negate this issue, and if in use 3 days ago. The captain could have re-entered the cockpit. Same with Ethiopian last year and possibly MAS370.