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6/17/21 

AIM 

“Reported Temperature” row. Round this number as 
applicable and then add to the final MA altitude only. 

(b) 

Aircraft with temperature compensating 

system: If flying an aircraft equipped with a system 
capable of temperature compensation, follow the 
instructions for applying temperature compensation 
provided in the AFM, AFM supplement, or system 
operating manual. Ensure the temperature compensa-
tion system is on and active prior to the segment(s) 
being corrected. Manually calculate an altimetry 
correction for the MDA or DA. Determine an 
altimetry correction from the ICAO table based on 
the reported airport temperature and the height 
difference between the MDA or DA, as applicable, 
and the airport elevation, or use the compensating 
system to calculate a temperature corrected altitude 
for the published MDA or DA if able. 

f. 

Acceptable Use of Table for manual CTA 

altitude correction: (See TBL 7

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1.) Pilots may 

calculate a correction with a visual interpolation of 
the chart when using reported temperature and height 
above airport. This calculated altitude correction may 
then be rounded to the nearest whole hundred or 
rounded up. For example, a correction of 130 ft. from 
the chart may be rounded to 100 ft. or 200 ft. A 
correction of 280 ft. will be rounded up to 300 ft. This 
rounded correction will be added to the appropriate 
altitudes for the “Individual” or “All” segment 
method. The correction calculated from the table for 
the MDA or DA may be used as is or rounded up, but 
never rounded down. This number will be added to 
the MDA, DA, and all step

down fixes inside of the 

FAF as applicable. 

1. 

No extrapolation above the 5000 ft. column is 

required. Pilots may use the 5000 ft. “height above 
airport in feet” column for calculating corrections 
when the calculated altitude is greater than 5000 ft. 
above reporting station elevation. Pilots must add the 
correction(s) from the table to the affected segment 
altitude(s) and fly at the new corrected altitude. Do 
not round down when using the 5000 ft. column for 
calculated height above airport values greater than 
5000 ft. Pilots may extrapolate above the 5000 ft. 
column to apply a correction if desired. 

2. 

These techniques have been adopted to 

minimize pilot distraction by limiting the number of 
entries into the table when making corrections. 

Although not all altitudes on the approach will be 
corrected back to standard day values, a safe distance 
above the terrain/obstacle will be maintained on the 
corrected approach segment(s). Pilots may calculate 
a correction for each fix based on the fix altitude if 
desired. 

NOTE

 

Pilots may use Real Time Mesoscale Analysis (RTMA): 
Alternate Report of Surface Temperature, for computing 
altitude corrections, when airport temperatures are not 
available via normal reporting. The RTMA website is 
http://nomads.ncep.noaa.gov/pub/data/nccf/com/rtma/ 
prod/airport_temps/. 

g. 

Communication: Pilots must request approval 

from ATC whenever applying a cold temperature 
altitude correction. Pilots do not need to inform ATC 
of the final approach segment correction (i.e., new 
MDA or DA). This request should be made on initial 
radio contact with the ATC facility issuing the 
approach clearance. ATC requires this information in 
order to ensure appropriate vertical separation 
between known traffic. Pilots should query ATC 
when vectored altitudes to a segment are lower than 
the requested corrected altitude. Pilots are encour-
aged to self

announce corrected altitude when flying 

into a non

towered airfield. 

1. 

The following are examples of appropriate 

pilot

to

ATC communication when applying cold

 

temperature altitude corrections. 

(a) 

On initial check

in with ATC providing 

approach clearance: Missoula, MT (example below). 

  Vectors to final approach course: Outside 

of IAFs: “

Request 9700 ft. for cold temperature 

operations.” 

  Vectors to final approach course: Inside of 

ODIRE:

 “Request 7300 ft. for cold temperature 

operations.

” 

  Missed Approach segment: “

Require 

final holding altitude, 12500 ft. on missed approach 
for cold temperature operations.

” 

(b) 

Pilots cleared by ATC for an instrument 

approach procedure; “Cleared the RNAV (GPS) Y 
RWY 12 approach (from any IAF)”. Missoula, MT 
(example below). 

  IAF: “

Request 9700 ft. for cold tempera-

ture operations at LANNY, CHARL, or ODIRE.

” 

Cold Temperature Barometric Altimeter Errors, Setting Procedures and Cold Temperature 

7

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Airports (CTA)