Hello, SLF here.
Just a question, out of curiosity, to all the Captains out here. So in your opinion - what are the justified circumstances whereby a Captain would allow a passenger to enter the flight deck?
Somehow - at least in my opinion - allowing this because the person is a friend/family/nice/famous/good looking/just plain curious - is not a justifiable reason. I mean - there are tens of thousands of professions out there where this would be absolutely unthinkable on grounds of professionalism and work ethics. Can you imagine, say a cashier at the bank inviting a friend to sit with her inside her glass cubicle for a bit of chit chat? Or a doctor having her husband sit by while she's examining patients? A teacher inviting someone over to the classroom without clearing it with the headmistress? Have you ever seen a tube or train driver invite a passenger into the cabin? Would you like to have staff's kids having a crèche at the control room of the nuclear power plant just down the road from your house?