737 MAX Flight Crew Operations Manual
Flight Management, Navigation -
Navigation Systems Description
MN-FLT-OH-201
11.20.17
The nominal Flight Path Weather envelope is ±4,000 ft with respect to the
expected flight path. At cruise altitudes above 29,000 ft MSL, the floor of
the envelope is extended down to 25,000 ft MSL when necessary to ensure
that relevant convective activity is displayed. On the ground and during
departure or approach the ceiling of the envelope is fixed at 10,000 ft MSL.
This provides approximately 10 minutes of look-ahead. Secondary weather
is displayed for situational awareness and to aid in making changes to your
flight plan to avoid "flight path" weather.
• MAN – Manual weather mode provides a means to assess storm cell
height and development by providing selectable altitude slices. These
slices from the 3D memory are corrected for the curvature of the earth,
providing a view at a constant MSL altitude level. Selecting MAN on
the mode selection knob enters the manual mode. Upon initial selection,
the altitude slice is set to the current aircraft altitude (nearest 1000 feet).
The altitude (ALT) knob is used to select the desired altitude slice from
0 to 60,000 feet MSL in 1,000 foot intervals. Turbulence information
and secondary weather information is removed in MAN mode to
enhance analysis of weather reflectivity.
The IntuVue Radar also includes the following features:
• Predictive Hail and Lighting (Hazard Display) – icons will be displayed
on top of the reflectivity to identify areas that have the signature
characteristics of hail, lightning, or both. The radar does not directly
detect hail or lightning; it analyzes the data in the 3D memory to
identify areas that have a high probability of containing these hazards.
• Rain Echo Attenuation Compensation Technique (REACT) – as the
transmitted radar signal travels through heavy rain it loses power, or
becomes attenuated. If this attenuation is severe enough, weather behind
a storm cell may not be detectable, or it may be displayed as being less
severe than it actually is. REACT automatically indicates areas where
the radar signal has been attenuated. These areas are shown as magenta
arcs superimposed over the reflectivity in the areas where the signal
attenuation is significant.
March 1, 2021
