TCAS (TRAFFIC ALERT
AND COLLISION
AVOIDANCE SYSTEM)
GENERAL
The TCAS I or TCAS II is manufactured by
Allied Signal. The controls and displays are
integrated with the Primus 1000. Controls are
through the RMUs and TCAS/annunciator dis-
plays are on the MFD and PFDs. On those air-
planes equipped with TCAS II, the RA
(resolution advisories) are integrated with the
vertical speed indicator display on the PFDs.
There is no RA display on TCAS I equipped
airplanes. Aural commands and advisory mes-
sages are through the audio control system.
The TCAS interrogates other airplane
transponders and analyzes the replies to de-
termine range and bearing of the intruder. In
addition, if the intruder’s transponder is re-
porting altitude, the relative altitude is also de-
termined. If the system predicts that safe
boundaries may be violated, it issues a TA
which is displayed on the MFD. Should the
TCAS II processor determine that a possible
collision hazard exists, it issues visual and
audio advisories to the crew to initiate ap-
propriate vertical avoidance maneuvers. TCAS
is unable to detect an airplane without an op-
erating transponder. If an airplane has a
transponder, but does not have altitude re-
porting, the TCAS will depict it on the TA
display, but without the altitude information
tag, and without the capability of providing
evasive commands. The pilot should not ma-
neuver the aircraft based on the traffic display
only. Pilots are authorized to deviate from
their current ATC clearance to the extent nec-
essary to comply with a TCAS resolution ad-
visory (RA).
With TCAS II installed, the Learjet 45 will also
be equipped with a Mode S ATC Transponder.
TCAS II is capable of generating a TA display
of traffic from Mode A transponder equipped
airplanes, and it is also capable of generating
RA signals to avoid Mode C equipped traffic.
For similar Mode S equipped traffic, the air-
plane’s TCAS II system coordinates evasive
maneuvers for both aircraft. TCAS I can pro-
cess transponder information from other air-
planes equipped with Mode A, C or S
transponders, but does not compute or coor-
dinate a resolution advisory (RA).
CONTROLS AND DISPLAYS
Mode
Selection of the TA or TA/RA modes is ac-
complished through the transponder window
on either RMU main radio tuning page (Figure
16-53). After the cursor is placed over the
transponder mode line, the desired mode is se-
lected with the RMU tuning knob.
Subsequently depressing the adjacent LSK
(line select key) alternately switches the
ATC/TCAS between STANDBY and the op-
erating mode selected with the RMU tuning
knob.
LEARJET 45 PILOT TRAINING MANUAL
16-98
FOR TRAINING PURPOSES ONLY
FlightSafety
international
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