737 MAX Flight Crew Operations Manual
Warning Systems
Chapter 15
System Description
Section 20
MN-FLT-OH-201
15.20.1
20 System Description
System Description
File Highlight
Introduction
Aural, tactile and visual warning signals alert the flight crew to conditions
requiring action or caution in the operation of the airplane. The character of the
signals varies, depending upon the degree of urgency or hazards involved. Aural,
tactile, and visual signals are used singularly or in combination to simultaneously
provide both warnings and information regarding the nature of the condition.
Mach/airspeed warnings, landing gear warnings, takeoff configuration warnings,
windshear warnings, and ground proximity warnings are discussed in this section.
Cabin altitude warning is discussed in this section and in the Air Systems chapter,
and autopilot and autothrottle disengage warnings are discussed in the Automatic
Flight chapter. The conditions which excite the fire warning bell are discussed in
the Fire Protection chapter.
Conditions which require the immediate attention of the flight crew are indicated
by red warning lights located in the area of the pilots’ primary field of vision.
These lights indicate engine, wheel well, cargo, or APU fires; autopilot,
autothrottle disengages; and landing gear unsafe conditions.
Conditions which require the timely attention of the flight crew are indicated by
amber caution lights.
Blue lights inform the flight crew of electrical power availability, valve position,
equipment status, and flight attendant or ground communications. Blue lights are
for information and do not require immediate flight crew attention. Some system
blue lights indicate a transitional state by illuminating bright as valves or
components reposition, then returning to a dim blue when the required
configuration is reached.
Green lights indicate a fully extended configuration, e.g., landing gear and leading
edge devices.
For specific information regarding red, amber, blue, and green lights refer to the
appropriate systems chapters.
Stall warning is provided by a control column shaker on each control column.
Various aural signals call attention to warnings and cautions. An aural warning for
airspeed limits is given by a clacker, the autopilot disengage by a warning tone,
takeoff configuration and cabin altitude by an intermittent horn, and landing gear
positions by a steady horn. The fire warning by a fire warning bell. Ground
proximity warnings and alerts, and windshear warnings and alerts are given by
voice warnings.
March 1, 2021
