User's Manual

SYSTEM DESCRIPTION AND INSTALLATION MANUAL
T
3
CAS/Part No.9005000
(3) Aural Messages
The TCAS generates aural alerts or messages announced over the aircraft audio
system. These messages accompany the visual TA or RA display and are
softened or strengthened, depending on the urgency of the situation. The TCAS
audio level is preset and is not adjustable by the aircrew.
If a logic change occurs before a message is completed and a new message is
initiated, the original alert is terminated and the new alert announced
immediately.
(a) Requirements and Limitations
The following is a list of the requirements and limitations for issuing an
aural advisory by the T
3
CAS Computer Unit:
1 Voice announcements are inhibited below 500 feet (152.4 meters)
above ground level (AGL).
2 The CANCEL BUTTON, which is a reserved input on the 9005000-
10000, -10101, -10202, and -10204 T
3
CAS CUs, only halts voice
announcements after the CANCEL BUTTON is activated. An aural
advisory in progress is terminated and not repeated after
deactivation of the CANCEL BUTTON.
3 During T
3
CAS computer unit self-test, an aural advisory confirms
proper operation of the aural advisory system by annunciating the
message “TCAS TEST”. The aural advisory system annunciates the
pass/fail status of any monitored functions with the messages “TCAS
TEST PASS” and “TCAS TEST FAIL”, respectively.
4 An aural advisory tone will precede each aural advisory when the
audio tone enable program pin has been activated.
5 T
3
CAS computer unit TCAS aural alerts are inhibited when the
advisory inhibit discrete inputs 2, 3, or 4 are grounded. An aural
advisory in progress is disabled after the grounding of advisory
inhibit discrete. The truncated message is annunciated in its entirety
once the inhibit discrete has been released. This capability is used to
defer all advisory (TA and RA), aural alert, and visual alert outputs
until another, higher priority announcement/alert is completed. See
Table 4-1 for RBP-5A, 5B, 5C and 5D.
6 Increases and decreases in the threat level are aurally annunciated.
However, decreases in threat level are annunciated once and are not
preceded by setting the audio tone discrete. For example, a vertical
speed restriction following a climb RA is annunciated once.
(b) Traffic Advisory (TA) Message
The traffic advisory aural alert, TRAFFIC - TRAFFIC is spoken once, and
then inhibited until the next TA occurs. This alert occurs when TCAS
predicts an intruder will enter the collision area within 20 to 48 seconds.
Simultaneously, the TCAS traffic display shows the location of the
intruder.
Pub. No. 8600200-001, Revision 004
34-45-29
1-82
04 Nov 2014
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