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1 Dec 2003
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MAINTENANCE MANUAL
CAS-100 COLLISION AVOIDANCE SYSTEM
Use or disclosure of information on this page is subject to the restrictions in the proprietary notice of this document.
TCAS equipment operates at the same transmit and receive frequencies as ground stations
(1030 MHz transmit and 1090 MHz receive). TCAS and ground stations operate at transmit
and receive frequencies that are inverse to transponder transmit and receive frequencies
shown below:
TCAS interrogates only in Mode C and Mode S by transmitting 1030-MHz messages through
the top and bottom TCAS antennas. TCAS receives 1090-MHz messages from Mode S and
ATCRBS Mode A or Mode C transponders through the top directional antenna and the bottom
TCAS omni or directional antenna.
If TCAS receives a Mode C reply from a Mode A transponder or a Mode C transponder that is
not supplied with altitude data, it will process the reply as a NAR reporting Mode C equipped
aircraft.
TCAS does not interrogate in Mode A. However, an aircraft equipped with a minimal
transponder that replies to Mode A interrogations, will reply to Mode C interrogations with no
altitude-encoded data present in the reply. TCAS tracks such aircraft in bearing and range,
and will display the aircraft a nonthreat intruder, proximity intruder, or traffic advisory. However,
a resolution advisory will not be generated since the correction maneuver (e.g., fly up, fly
down) cannot be determined without intruder altitude data.
B. Equipment Part Numbers
The required and optional TCAS equipment, including aircraft systems are:
•
TCAS processor (required equipment)
•
Top-mounted directional antenna (required equipment)
•
Bottom-mounted omni or directional antenna (required equipment)
•
Installation selectable combinations of resolution advisory (TA/VSI or RA/VSI) and
traffic advisory displays [TA/VSI, plane position indicator (PPI), dedicated, etc.]
(required equipment)
•
Mode S transponder (required equipment)
•
Required aircraft equipment
•
Optional aircraft equipment.
System
Transmit Frequency
Receive Frequency
Mode S Transponder
1090 MHz
1030 MHz
Mode A/C ATCRBS Transponder
1090 MHz
1030 MHz
TCAS
1030 MHz
1090 MHz
Ground Station
1030 MHz
1090 MHz