I seem to remember that not so very long ago - in the UK with it's very strict firearm laws - a (duly authorized) armed bodyguard to an on board VIP managed to leave his loaded weapon in the toilet of a commercial aircraft. It was found by a rather shocked pax shortly thereafter and handed to an equally shocked hostie.
The consequences of this scarcely bear thinking about. (The so called "responsible" individual was, I understand, dismissed summarily from his close protection position - and subsequently from the force.)