Path: scolex!sco!uunet!uunet!cs.utexas.edu!utgpu!cunews!fultz
From: fultz@scs.carleton.ca (Brian Fultz)
Newsgroups: rec.aviation
Subject: Cold Weather Flying
Message-ID: <1991Nov12.133316.21981@cunews.carleton.ca>
Date: Tue, 12 Nov 91 05:33:16 PST
Sender: news@cunews.carleton.ca
Organization: School of Computer Science, Carleton University, Ottawa, Canada
Lines: 45

Further on the topic of Cold Weather Flying.  Up in Canada we have to
do a little correction to the heights we fly ( this correction is 
done in the U.S. by the Air Force only, others are expected to kill them 
selves ).  I type in from the Canada Air Pilot in a long quote:

Cold Temperature Corrections:

Pressure altimeters are calabrated to indicate the true altitude under
ISA conditions.  Any deviation from ISA will result in an erroneous reading on
the altimeter. In the case when the temperature is higher than ISA the true
altitude will be higher than the figure indicated by the altimiter and the true
altitude will be lower when the temperature is lower than ISA.  The altimeter
error may be significant and becomes extremely important when considering
obsticle clearences in very cold temperatures.

the following procedures apply:
1)IFR altitudes may be accepted or refused
2)IFR altitudes will not be adjusted 
3) radar vectoring altitudes will not be adjusted
4)when the following adjustments are used the pilot must advise ATC

Correction chart:
A/D temp         height above aerodrome ( HAA,  feet )
          200 300 400 500 600 700 800 900 1000 1500 2000 3000 4000 5000
0C          0  20  20  20  20  40  40  40   40   60   80  140  180  220
-10C       20  20  40  40  40  60  80  80   80  120  160  260  340  420
-20C       20  40  40  60  80  80 100 120  120  180  240  380  500  620
-30C       40  40  60  80 100 120 140 140  160  240  320  500  660  820
-40C       40  60  80 100 120 140 160 180  200  300  400  620  820 1020
-50C        40 80 100 120 140 180 200 220  240  360  480  740  980 1220 

worked example you are going to "Broken Crotch, Alberta" mid January
Aerodrome Elevation 2262 feet ASL temp -50C
                 Altitude     HAA    Correction     fly indicated

Procedure turn       4000     1738         +420              4420
FAF                  3300     1038         +240              3540
MDA STR IN           2840      578         +140              2980


end of quote
Personal comment:  This is the type of item which if not understood
or forgotten gets you a note in the accident statistics.  I do not
know why American non military people are thought by the government
to be unable to make this correction