737 MAX Flight Crew Operations Manual
Warning Systems -
System Description
MN-FLT-OH-201
15.20.11
These alerts are “radio altitude based alerts.” The GPWS does not alert the flight
crew toward vertically sheer terrain or slow descent into unprepared terrain while
in the landing configuration.
The GPWS also monitors terrain proximity using an internal world wide terrain
data base. Proximate terrain data shows on the navigation display. If there is a
potential terrain conflict, alerts are provided based on estimated time to impact.
These alerts are “look-ahead terrain alerts.”
Ground proximity alerts are accompanied by voice aural alerts and the PULL UP
annunciation on the attitude indicators or, for deviation below glideslope alert, the
BELOW G/S light.
Note:
Terrain ahead of the airplane may exceed available climb performance. A
ground proximity alert does not guarantee terrain clearance.
Look-ahead terrain alerts and radio altitude based alerts are prioritized based on
the level of hazard and the required flight crew reaction time. Look-ahead terrain
alerts and radio altitude based alerts are inhibited by an actual windshear warning
(airplane in windshear).
Look–Ahead Terrain Alerting
The GPWS terrain data base contains detailed terrain data near major airports, and
data in lesser detail for areas between airports. Terrain within 2,000 feet of
airplane barometric altitude shows on the navigation display. The terrain data is
not designed to be an independent navigation aid.
The terrain display is generated from a data base contained in the GPWS computer
and correlated to GPS position.
Terrain and weather radar cannot show together on a display. If one pilot selects
terrain and the other pilot selects weather radar, each display updates on
alternating sweeps. All other displays (TCAS, LNAV routing, etc.) can show with
terrain data.
Look-ahead terrain alerts are based on the airplane’s position, barometric altitude,
vertical flight path, and ground speed.
October 26, 2021