Under “similar threads” below there are two good discussions. I think the bottom line is; there is no universally applied and accepted standard for non standard ISA, vectoring altitude corrections.
For the pilots, published instructions exist but generally they are not well understood. This is an education problem. Pilots need to understand the phenomenon, make the required corrections and then notify ATC of their actions. It’s interesting to me that there have been no U.S.A. or Canadian controllers join in the discussion (I think).
From my observation of the flight deck the vast majority of pilots have little understanding of the phenomenon therefore do not understand its ramifications nor do they apply any correction to the published or assigned altitudes.
On the other side of the coin (the point that was brought up in a recent post); yes if it is hotter than ISA, then flying the published altitudes will result in the aircraft being higher than it would be under ISA conditions.
I just received the following quoted response from the U.S. ATC facility where I first experienced this phenomenon. "We do not make any adjustments to our Minimum Vectoring Altitude due to temperature variations. Personal controller experience and technique may keep some flight higher but generally speaking we adhere to the requirement in FAA Order JO 7110.65."
The document referenced is some 605 pages in length. Having searched it I have not yet come across any mention of modifying assigned altitudes due to lower than ISA temperatures. I will keep looking but I doubt it is there. It seems I have the answer to my original question. In the U.S. altitudes assigned by ATC are not modified due to higher or lower than ISA temperatures.
Last edited by Northbeach; 8th Jan 2009 at 01:14.