Hi Alan
I think that the reason you have had no replies to this thread is that most helicopter pilots do not consider the increased fuel efficiency with altitude a very relevant factor in their day to day flying. Wind is by far the most important factor and low in a head wind high in a tail wind usually works as far as speed to destination is concerned. I sometimes go at flight level ridiculous in the summer to find cooler air for the oil workers cocooned in their survival suits.
HF
