AF> Watch the weather reports for mountains in your area. The temperature at AF> altitude will be closer to mountain temps than ground temps. I recall AF> turning up to a job at a town at 1000m ALT where the temperature was AF> pleasantly warm. However snow was forecast for 1500m and above, so I AF> carried my ski parka with me, to the mirth of my associates. Ten minutes AF> later I could have sold that parka for almost any sum I could name, but then AF> I'd be freezing my own arse off :-)
The simple aproximate rule is that from sea level, for each kilometer of height the temperature drops by 6 degrees Celsius. Of course, weather - cold fronts, also the rapid wind (get some pertex or other windproof) if the helicopter is in motion from the open windows, can lower the temp more. Good light, Frantisek Vlcek
