When 3,000' is NOT 3,000'
Max Angle,
Agreed if the temperatures are significantly below ISA then the printed MSL altitudes on the approach chart need to be adjusted. My impression is that this is not a well understood phenomenon by many pilots.
Your second statement regarding ATC is exactly my question. I am not at all sure ATC compensates for non standard temperatures. It’s a big world and I am sure some do. However, if you find yourself flying someplace that is experiencing sub zero frigid temperatures it is a real concern. Under those circumstances flying non temperature corrected altitudes (the ones printed on the approach plate or issued by ATC {possibly}) will result in significantly decreased separation from the underlying terrain.
My general impression is that I am not in fact “protected” by ATC when extremely cold temperatures exist at the aerodrome I am landing at. Last winter I was vectored to an ILS at the same assigned final altitude prior to intercepting the glide slope that they use during the summer. With no surprise we intercepted the glide slope well past (inside) the glideslope intercept point or the FAF. I was really surprised as this aerodrome is just outside the Arctic Circle and frequently experiences such conditions and the airport has been in operation for 60+ years. Here is their current weather, I just checked it: 031915Z 0000 1/16sm R01L/2400v2800ft FZFG BKN001 M41/ 29.97 RMK A02 FG BKN000. We were in VMC and I had the terrain in sight so I accepted it because the experience provided a good “teaching moment”.
I think the Canadians have this figured out. I’m learning about Europe from the responses.
I have been told that at some military airports in the U.S.A. altitudes are temperature compensated. I do not believe ATC assigned altitudes are corrected in the U.S.A. at civilian airports-we are on our own. Ya’ll be careful out there.
Last edited by Northbeach; 3rd January 2009 at 19:04.