737 MAX Flight Crew Operations Manual
Flight Instruments, Displays -
MAX Display System - System
Description
10.20.10
MN-FLT-OH-201
Standby Flight Instruments
The standby flight instruments include:
Standby Magnetic Compass
A standard liquid–damped magnetic standby compass is provided. A card located
near the compass provides correction factors.
Integrated Standby Flight Display (ISFD)
1B401, 1B402, 1B801 - 1B824
The ISFD displays attitude, airspeed, altitude, localizer/glideslope deviation and
magnetic heading information. Attitude information is computed from data
provided by internal inertial sensors. Airspeed and altitude are computed from
pneumatic pressure data provided by direct connections to the auxiliary pitot and
alternate static sources. Localizer/Glideslope deviation is provided by the #1
MMR. Magnetic heading is provided by the ADIRU-L. Magnetic heading is not
available in polar regions. The ISFD will automatically switch to True Heading
when Magnetic Heading becomes unusable in polar regions.
Note:
The standby magnetic compass must be used to validate information.
The battery bus powers the ISFD. Selecting the battery switch ON activates the
ISFD. After 10 seconds, an initialization sequence begins that requires 90 seconds
to complete. ATT and INIT 90s messages are displayed during initialization.
Initialization will stop if airplane movement is excessive and will resume when
airplane movement is acceptable for initialization. Upon completion of the
initialization sequence, attitude information is displayed.
Detection of a momentary out-of-limit ISFD condition may cause the attitude
display to blank and the WAIT ATT or ATT:RST message to display. Operation of
the attitude reset switch is required in response to the ATT:RST message. This will
reset the horizon line with the airplane symbol.
On the ground, operation of the attitude reset switch must be performed with the
airplane stationary. In flight, operation of the attitude reset switch must be
performed with the airplane in wings level, non-accelerated flight. During the
process, the ATT 10s message displays. Failure to maintain straight and level
flight for 10 seconds may result in an ATT:RST message. If the reset attempt is
unsuccessful, the ATT:RST message remains displayed and the ISFD does not
enter normal operation.
Radio Altimeter (RA)
The radio altimeter measures airplane altitude above terrain. Radio altitude is
displayed on the PFD.
• standby magnetic compass
• integrated standby flight
display
March 1, 2021
