737 MAX Flight Crew Operations Manual
Supplementary Procedures -
Adverse Weather
SP.16.12
MN-FLT-OH-201
Verify that the L and R VALVE OPEN lights illuminate
bright, then extinguish.
Cold Temperature Altitude Corrections
Extremely low temperatures create significant altimeter errors and greater
potential for reduced terrain clearance. When the temperature is colder
than ISA, true altitude will be lower than indicated altitude. Altimeter
errors become significantly larger when the surface temperature
approaches -30°C or colder, and also become larger with increasing height
above the altimeter reference source.
Apply the altitude correction table when needed:
• apply corrections to all published minimum departure, en route and
approach altitudes, including missed approach altitudes, according to
the table below. Advise ATC of the corrections
• MDA/DA settings should be set at the corrected minimum altitudes
for the approach
• corrections apply to QNH and QFE operations.
To determine the correction from the Altitude Correction Table:
• subtract the elevation of the altimeter barometric reference setting
source (normally the departure or destination airport elevation) from
the published minimum altitude to be flown to determine “height
above altimeter reference source”
• if the corrected indicated altitude to be flown is between 100 foot
increments, set the MCP altitude to the closest 100 foot increment
above the corrected indicated altitude to be flown.
• enter the table with Airport Temperature and with “height above
altimeter reference source”. Read the correction where these two
entries intersect. Add the correction to the published minimum
altitude to be flown to determine the corrected indicated altitude to
be flown. To correct an altitude above the altitude in the last column,
use linear extrapolation (e.g., to correct 6000 feet or 1800 meters, use
twice the correction for 3000 feet or 900 meters, respectively.) The
corrected altitude must always be greater than the published
minimum altitude
• do not correct altimeter barometric reference settings.
March 1, 2021