"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 7-3-1.) 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 temperature operations at LANNY, CHARL, or ODIRE."

Cold Temperature Barometric Altimeter Errors, Setting Procedures and Cold Temperature
Airports (CTA)

7-3-5