Embraer EMB145 Operation Manual page 1606

CREW
AIRPLANE
AWARENESS
OPERATIONS
MANUAL
AURAL WARNINGS
There are two kinds of aural warnings: voice messages and tones.
Voice messages are normally associated with warning messages on
EICAS or other warning systems. They are generated whenever a
potentially dangerous condition exists, as determined by the GPWS,
TCAS and windshear detection system. There are some voice
messages that can be cancelled, but others can only be cancelled
when the cause that triggered them has been eliminated.
Tones have different forms and indicate some notable airplane events,
sometimes in unison with voice messages.
AURAL WARNING UNIT
In order to generate messages and tones, the Aural Warning Unit
(AWU) receives signals from the following airplane systems:
− TCAS;
− Windshear detection system;
− GPWS;
− IC-600;
− Fire detection system;
− Stall protection system;
− Trims;
− Flaps;
− Brakes;
− Spoilers;
− Radio altimeter;
− Autopilot;
− Landing gear;
− ADC;
− Pressurization;
− SELCAL.
The AWU sends the appropriate audio signal to an audio digital
system, which routes the messages to the appropriate speakers.
AWU POWER SOURCE
The AWU is supplied by one DC bus and one Essential DC bus, and is
provided with two channels, A and B. Channel B is kept as a backup
for channel A, and is automatically activated should channel A fail.
Page Code
2-04-15 1 01
REVISION 37