I'm afraid Wiggy is correct. Tell me, how would having a sweet twenty-something or other cabin crew member sitting in the otherwise vacant F/O seat stop me from doing something I really ought not to? Will she whack me with fire axe? Will she be able to find the radio page? After I trip a C/Bs will she be able to open the door? This is a pointless box ticking exercise. One of the few defences against insane acts is a proper staff welfare monitoring program. A starting point might be something quite simple as a cup of free company coffee whilst reading through your briefing. Or a simple chat with the driver of the crew transport. But this costs money and after all, airlines sub most of these things out and buy insurance to cover themselves against losses caused by staff action. But nobody cares. Instead, we have to face the Gestapo will continue to p!ss us off with enforcement of "no yoghurts or pointy sticks" policy, yet fail to determine if we should even be where we are... Basically, provided not too many people are killed too often nothing will happen, because... nobody really cares.