In Alaska, the mountains grow taller in the winter.
https://www.tc.gc.ca/eng/civilaviation/publications/tp185-4-06-operations-4024.htm
https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0702.html
http://allaboutairplanes.wordpress.com/2011/08/31/correction-formula-on-altimeters-in-cold-weather/
http://www.bluecoat.org/reports/Long_98_Cold.pdf
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0CEEQFjAF&url=http%3A%2F%2F44rf.com%2Fmisc%2FUSAF_AIS_Cold_WX_Altimeter.ppt&ei=vBs4VMW-LsaEiwLkroHgBQ&usg=AFQjCNGF-SSNHwxTg6iyWlG86etL2ZpK7A&sig2=P2K44WuCiog9STSB3sbPAw&bvm=bv.77161500,d.cGE
C=h(15-to)/273+to-.5k(e+h)
h=height above facility
k=standard temperature laps rate (.00198degC/ft or .0065degC/meter
e=facility elevation
t-facility temperature
to=facility temp. adjusted to mean sea-level (to=t+ke)
thus C= the altitude correction value.
You may have heard, "high to low, lookout below."
What's missing is, "Mountains grow taller in the winter."
Yes, the cold weather altimeter error is far more extreme than appreciated. GPS altitude helps. Canada corrects vectored altitudes for cold, but I cannot confirm that the US does, and the FAA advisories are few and far between. Furthermore, pilots must request higher rather than merely adjusting for cold. By the time the pilot runs the formula above, the aircraft may already run into a mountain. The charts for cold-correction apply to approaches and stop at 5,000 ft. The error increases with altitude, so the discrepancy may exceed a thousand feet or more at the mountain tops, say 2,000 or more for Denali. Be assertive, demand higher than MEAs. Also note that flight level 18 at 29.92 will interfere with VFR traffic below.
Jet fuel crystallization becomes a concern at 37C outside temperature or 41C fuel temperature. Reciprocal engine Cessnas cope with the cold as long as they are properly winterized, and wow does the performance ever improve -- especially on skis. Don't try it, however, without a preheat and installing the winter conversion by an experienced Alaska AI. With clear skies, winter flying can be spectacularly rewarding.
https://www.tc.gc.ca/eng/civilaviation/publications/tp185-4-06-operations-4024.htm
https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0702.html
http://allaboutairplanes.wordpress.com/2011/08/31/correction-formula-on-altimeters-in-cold-weather/
http://www.bluecoat.org/reports/Long_98_Cold.pdf
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0CEEQFjAF&url=http%3A%2F%2F44rf.com%2Fmisc%2FUSAF_AIS_Cold_WX_Altimeter.ppt&ei=vBs4VMW-LsaEiwLkroHgBQ&usg=AFQjCNGF-SSNHwxTg6iyWlG86etL2ZpK7A&sig2=P2K44WuCiog9STSB3sbPAw&bvm=bv.77161500,d.cGE
C=h(15-to)/273+to-.5k(e+h)
h=height above facility
k=standard temperature laps rate (.00198degC/ft or .0065degC/meter
e=facility elevation
t-facility temperature
to=facility temp. adjusted to mean sea-level (to=t+ke)
thus C= the altitude correction value.
You may have heard, "high to low, lookout below."
What's missing is, "Mountains grow taller in the winter."
Yes, the cold weather altimeter error is far more extreme than appreciated. GPS altitude helps. Canada corrects vectored altitudes for cold, but I cannot confirm that the US does, and the FAA advisories are few and far between. Furthermore, pilots must request higher rather than merely adjusting for cold. By the time the pilot runs the formula above, the aircraft may already run into a mountain. The charts for cold-correction apply to approaches and stop at 5,000 ft. The error increases with altitude, so the discrepancy may exceed a thousand feet or more at the mountain tops, say 2,000 or more for Denali. Be assertive, demand higher than MEAs. Also note that flight level 18 at 29.92 will interfere with VFR traffic below.
Jet fuel crystallization becomes a concern at 37C outside temperature or 41C fuel temperature. Reciprocal engine Cessnas cope with the cold as long as they are properly winterized, and wow does the performance ever improve -- especially on skis. Don't try it, however, without a preheat and installing the winter conversion by an experienced Alaska AI. With clear skies, winter flying can be spectacularly rewarding.
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