737 Flight Crew Operations Manual
Supplementary Procedures -
Adverse Weather
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
SP.16.18 D6-27370-866-EGP
Note: If only cooling air from a ground air conditioning cart is supplied
(no pressurized air from the APU or ground external air), then the
TAT probes are not aspirated. Because of high TAT probe
temperatures, the FMC’s may not accept an assumed temperature
derate. Delay selecting an assumed temperature derate until after
bleed air is available.
If these actions do not reduce cabin temperatures sufficiently:
PASSENGER CABIN temperature
selector ....................................................................AUTO COOL
PACK switches ....................................................................HIGH
After engine start with the engines at ground idle, the pneumatic pressure
available to the bleed air system may not be sufficient to provide
adequate cooling during extended ground operations. Use of APU bleed
air instead of engine bleed air to supply the packs while on the ground
can significantly increase cabin cooling. If additional cooling is needed
during extended ground operations:
Engine BLEED 1 air switch....................................................OFF
Engine BLEED 2 air switch....................................................OFF
ISOLATION VALVE switch............................................... OPEN
APU BLEED air switch ........................................................... ON
PACK switches ....................................................................HIGH
Temperature selectors ............................................. AUTO COOL
Prior to takeoff:
PACK switches ...................................................................AUTO
Engine BLEED 2 air switch..................................................... ON
APU BLEED air switch ..........................................................OFF
Engine BLEED 1 air switch..................................................... ON
ISOLATION VALVE switch...............................................AUTO
Temperature selectors ................................................... As needed
September 15, 2016
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