737 Flight Crew Operations Manual
Warning Systems -
System Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
15.20.2 D6-27370-866-EGP
Various aural signals call attention to warnings and cautions. An aural warning for
airspeed limits is given by a clacker, the autopilot disconnect 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.
Generally, aurals automatically silence when the associated non–normal condition
no longer exists.
Master Fire Warning Lights
Two master FIRE WARN lights illuminate when any fire warning condition
occurs. The lights remain illuminated as long as the condition exists. Pushing
either master FIRE WARN light or fire warning bell cutout switch extinguishes
both lights, silences the fire warning bell and resets the system for future
warnings. Further information appears in the Fire Protection chapter.
Master Caution Lights
Two MASTER CAUTION lights illuminate when any caution occurs outside the
normal field of vision of the flight crew. The lights remain illuminated as long as
the caution condition exists, or until the crew resets the system. Pushing either
MASTER CAUTION light extinguishes both lights and resets the master caution
system for further cautions. Pushing either annunciator light panel recalls all
existing fault annunciations.
A single fault in certain redundant systems, also known as a "simple fault," does
not illuminate the MASTER CAUTION and system annunciator lights. However,
this type of fault is stored in the master caution system. Pushing the system
annunciator recalls the simple fault on the system annunciator panel.
When the MASTER CAUTION recall is pressed, all twelve system lights should
illuminate while the press-to-test feature is held. If a system annunciator light does
not illuminate, refer to the Dispatch Deviation Guide (DDG).
System Annunciator Lights
Two system annunciator light panels are located on the glare shield. The
annunciator light panels include only those systems located on the forward
overhead, aft overhead, and fire control panels. If a caution condition exists, the
appropriate system annunciator(s) and MASTER CAUTION lights illuminate.
March 27, 2014
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