CREW
AWARENESS
AIRPLANE
OPERATIONS
MANUAL
2-04-15
Page
2
Code
01
REVISION 37
AOM-145/1114
AWU POWER-UP TEST
An AWU power-up test is performed and generates aural warnings for
one or both channels operating normally. If both channels have failed,
the caution message AURAL WARN FAIL is displayed on EICAS.
AURAL WARNINGS LEVELS
The aural warnings are classified into four levels, presented below in a
decreasing level order:
− Emergency - Associated with situations that may be hazardous.
AWU generates a master warning tone (triple chime) before the
warning and voice message may be generated. In any case, the
aural warning is repeated every second until deactivated through the
master warning button or until the condition that generated the
warning has been eliminated.
− Abnormal - Associated with malfunctions or failures. AWU
generates a master caution tone (single chime) every five seconds,
until it is removed, canceled or replaced by a higher priority aural
warning. Voice messages are generated after each tone.
− Advisory - Associated with minor malfunctions or failures that lead
to loss of redundancy or degradation of the affected system’s
performance.
− Information - A remarkable event has occurred.
AURAL WARNINGS ANNUNCIATION PRIORITY
When multiple aural warnings are active, aural warnings among the
highest level alert groups shall be sounded first in order and repeated.
Once all alerts in the higher group are cancelled or removed, then the
second tier group alerts are sounded and repeated.
An alert in process shall be immediately interrupted when an alert of a
higher priority needs to be generated.
EXCEPTIONS TO AURAL WARNINGS PRIORITY
When an internal voice message is being annunciated, it shall be
completed before another alert, even of a higher priority, is
annunciated. This does not apply to internally generated tones which
shall be interrupted within 1 second.
If an emergency arises together with a warning that generates
continuous sounds, such as a fire or stall, the sound volume is
reduced to avoid misunderstanding of the remaining messages,
although being loud enough to still warn pilots.
The master warning tone is inhibited when any other emergency alert
(internal or external) is occurring at the same time.
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