G'Day to you TG too.
It does indeed seem strange that the AAIB report seems so slack on this occasion. I don't recall seeing any from them that was so slack as this one.
As for the question of 0.04 mcg being a tiny amount, 0.04 mcg isn't that hugely far off the therapeutic level, even considering the therapeutic level we're interested in discussing might be for for sleep-inducing effects (although CAMI states the therapeutic low as 0.1 mcg, it doesn't say for what - see below). Also, according to one of the reports that I saw, drowsiness can be observed at 0.03-0.04 mcg/mL, and mental impairment may be observed with concentrations above 0.06 mcg/mL. Therapeutic level for antihistamine effects are >0.025 mcg/mL according to the same document. So you could say that at 0.04 mcg/mL, it was in the therapeutic level, if the PH took it for antihistamine effect, although it was stated in the AAIB report that the likely reason was to aid sleep. Hence my thinking that it wasn't really a tiny amount as such. (Yes I did realise you were referring to the PH.)
I hazard a guess to say this would probably have been the rationale used by the pathology specialist in stating that "but the evidence indicated that it was highly probable that it corresponded to a therapeutic concentration of diphenhydramine.".
By the way, I am starting to wonder if "12 to 24 hours" wasn't a typo for "2 to 24 hours". This would make a little more sense in terms of what was stated elsewhere and the numbers.
Now this is purely a hypothetical question.
I am wondering if there could have been any factor that contributed to this accident, or more precisely to the failure to de-ice, from the human factors point of view, in that two captains were flying together. In my very unscientific research I have heard many stories that when captains fly together, their general alertness in relation to their airmanship can be reduced, thinking that the other pilot knows what he/she is doing, and that the authority gradient not being quite so clear can mean that they are a little more relaxed, possibly too relaxed. Does such a potential over-relaxation happen, and if so, could this have been a contributory factor in not de-icing the aircraft and not turning the anti-ice on, thinking "if the other guy thinks it's OK, it must be OK, as he must know what he's doing"? Any people with knowledge of human factors care to comment?
Last edited by Non Normal; 21st Aug 2004 at 13:26.