737 MAX Flight Crew Operations Manual
Flight Management, Navigation -
Navigation Systems Description
11.20.20
MN-FLT-OH-201
Associated Threats are shown while the system is in AUTO and WX+T mode is
selected. Associated threats show as red dots on the display and can be within the
cell boundary or outside. They are determined by temperature as well as
horizontal and vertical radar data. Two type of indications can be shown. The first
is the electrified region found in precipitation around the freezing level. This
indication shows when the freezing point is within 6000 feet of the aircraft.
Associated hazards include icing and lightning. The second type of indication
shows as red dots in a rectangle shape over the thunderstorm cell, and may extend
beyond the cell in the downwind direction any time the wind is greater than 10
knots above 25 000 feet. The anvil pattern above a storm cell is inferred from the
detected cell intensity, and indicates a potential of icing, hail and/or lightning. This
shows no matter which altitude the aircraft is at. The electrified region is active
for aircraft temperatures warmer than negative
20 degrees C.
Core Threat Adjustment provides a color and size adjustment to closer represent
the actual threat. The core threat assessment uses horizontal and vertical growth
rates and increases the color and size on the display if a return is below a certain
decibel threshold. Core Threat Adjustment functions in AUTO mode only with
WX+T selected.
Two-Level Turbulence Detection provides two levels of turbulence detection
when in AUTO and WX+T mode is selected. Severe turbulence is shown by solid
magenta areas, while light and moderate turbulence (known as ride quality
turbulence) is shown by magenta dots. Severe turbulence is indicated when the
aircraft g-load is 0.3 g or greater, while ride quality turbulence is indicated when
aircraft g-load is 0.2 g. When not in AUTO, the single level of turbulence (0.3g)
is available. Two-Level Turbulence Detection functions in AUTO mode only with
WX+T selected.
Flight Path/Descent Assessment shows weather for the descent profile as
soon as the aircraft starts a descent. All Multiscan Radar functions are available
on the descent. The user does not need to switch to Manual mode to observe
weather along the descent.
Windshear
On takeoff Warnings and Cautions are enabled from the beginning of the takeoff
roll (0 knots) until the aircraft reaches 80 knots. From 80 knots until the aircraft
passes 400 ft, only Warnings are enabled. From 400 ft through 1200 ft, Warnings
and Cautions are enabled. All new alerts are disabled from the time the aircraft
passes 100 knots until it reaches 50 ft.
March 1, 2021
