Since when do Cabin Crew perform bag searches? Sure, they have THEIR bags searched in hotel foyers but I don't seem to ever recall searching passengers bags on the aircraft?
Not sure if thats a response to my post or not... however if it is I will clarify what I meant re CC not being aware of the cylinder (on the ground during boarding) - I meant CC would not be aware of the cylinder for the exact reasons you say if it were carried on in a bag, as we dont (and I hope to god it never gets to the stage that we are required to) perform bag searches (excluding certain inflight circumstances).
Hope that clarifies!
Edited to note that an above post from a newspaper article is now saying that the cylinder was in the cargo hold - in which case the pax lied (either intentionally or through naievety) re the contents of his baggage when asked the DG questions (presuming of course he was asked them, which I am almost certain he would have been - I am in no way doubting JQs checkin practices nor am I attempting to slander JQ, however you do need to consider all possibilities).
What I *really* want to know though is why it was not removed from his baggage before going on the second flight??????????
