User's Manual

SYSTEM DESCRIPTION AND INSTALLATION MANUAL
TCAS 3000 Traffic Alert and Collision Avoidance System
34−43−23
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Page 1−56
15 Dec 2005
(d) An aural advisory tone will precede each aural advisory when the audio tone
enable program pin has been activated.
(e) TCAS computer unit aural alerts are inhibited when the advisory inhibit discrete
input No. 4 is grounded. An aural advisory in progress is disabled after the
grounding of advisory inhibit discrete No. 4. 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.
(f) 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.
(2) 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.
(3) Resolution Advisory (RA) Messages
Resolution advisories indicate evasive vertical maneuvers calculated to increase
separation between the TCAS aircraft and the intruder (corrective advisory), or to
indicate certain changes in vertical speed are not recommended (preventive).
Resolution advisory messages made up of a single word are repeated three times;
longer messages are repeated twice.
RAs are annunciated on the TCAS computer unit using the voice messages listed
below as determined by Collision Avoidance System (CAS) data. The following
messages will not immediately follow another message from this paragraph if it
causes a reversal of sense. For example, a “CLIMB, CLIMB, CLIMB” message
cannot immediately follow a :”DESCEND, DESCEND, DESCEND” message.
(a) “CLIMB, CLIMB, CLIMB”: Climb at the rate shown on the VSI or other suitable
indicator. The −XX003 TCAS CU message is “CLIMB, CLIMB”.
(b) “DESCEND, DESCEND, DESCEND”: Descend at the rate shown on the VSI or
other suitable indicator. The −XX003 TCAS CU message is :”DESCEND,
DESCEND”.
(c) “MONITOR VERTICAL SPEED”: Verify that vertical speed is out of the
illuminated red VSI arc, or comply with another suitable indicator. Additional
messages are “MAINTAIN VERTICAL SPEED, MAINTAIN: MAINTAIN
VERTICAL SPEED, CROSSING MAINTAIN”: or “ADJUST VERTICAL SPEED,
ADJUST”. Safe separation is based upon maintaining the current vertical speed.
(d) “ADJUST VERTICAL SPEED, ADJUST”: Reduce vertical speed to a speed out
of the illuminated red arc.