737 Flight Crew Operations Manual
Flight Instruments, Displays -
PFD/ND – System Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
D6-27370-866-EGP 10.21.13
Air Data
The pitot static system is comprised of three separate pitot probes and six flush
static ports. Two pitot probes and four static ports interface with the air data
modules. The remaining auxiliary pitot probe and alternate static ports provide
pitot and static pressure to the standby instruments. The auxiliary pitot probe is
located on the first officer’s side of the airplane.
The air data modules convert pneumatic pressure to electrical signals and send
these data to the ADIRUs. Each pitot air data module is connected to its on–side
pitot probe; there is no cross connection. The air data module connected to the
Captain’s pitot probe sends information to the left ADIRU, while the air data
module connected to the First Officer’s pitot probe sends information to the right
ADIRU. The remaining air data modules are located at the balance centers of the
Captain’s and First Officer’s static ports. The air data module connected to the
Captain’s static ports sends information to the left ADIRU, while the air data
module connected to the First Officer’s static ports sends information to the right
ADIRU.
Angle–of–Attack
There are two alpha vanes, one located on each side of the forward fuselage. The
vanes measure airplane angle–of–attack relative to the air mass.
Total Air Temperature (TAT)
A total air temperature probe is mounted outside the airplane to sense air mass
temperature. The temperature sensed by the probe is used by the ADIRUs to
compute total air temperature.
Note: For manual CDU input of OAT on the ground, TAT indication is
approximate and should not be used in lieu of ambient OAT for takeoff
performance.
Static Air Temperature (SAT)
Static air temperature, displayed on the CDU PROGRESS page, comes from the
ADIRUs, using total air temperature probe information.
September 26, 2013
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