I don't usually question the wisdom and knowledge of AAIB investigators (of whom I have the greatest respect) but I'm curious as to the inference that it may have been due to "High density altitude". If the air is highly dense then wouldn't this facilitate an improved climb rate whereas the accident related to a poor climb rate? This would suggest that the air was 'thinner' than normal, i.e. would be a lower pressure/density than normal? Thinking about it, shouldn't it be described as a "High altitude density" (i.e. lower air pressure, leading to an effect similar to taking off from a higher altitude airfield). Overall though, I'd be worried about flying in anything whose performance is potentially affected by a height difference of only a thousand feet or so.