Okay, thank you, as I said NO sinister reason for wanting to know, just we didn't have those secure doors for the almost 40 years I was in the Industry.
Could you, or someone else, just please provide a little more detail?
I get that you don't go, but does a U/S cockpit door lock nowadays make the aircraft unserviceable/not airworthy, OR is a different law/regulation, OR just Company policy??
Thank you..................