Air-To-Air Coordination Function; Data Recording Function; Data Loader Function; System Component Description And Functions - Honeywell CAS-100 Maintenance Manual

(7)

Air-to-Air Coordination Function

A maneuvering coordination data link is established with the intruder if the intruder
aircraft is TCAS equipped and becomes a threat . This data link makes sure that the
resolution advisories in the two TCAS equipped aircraft are controlled and compatible.
The control links are established between the two TCAS systems through the Mode S
transponder.
(8)

Data Recording Function

TCAS history data is at intervals moved from the processor to the recorder if the optional
data recorder is attached to the PCMCIA card interface on the TCAS processor.
(9)

Data Loader Function

A TCAS processor with the data loader function can receive a software update without
opening the unit if an ARINC 615-3 data loader is connected. Also, there is an option to
load data through a PCMCIA card put into the PCMCIA card interface slot on the front of
the processor.

5. System Component Description and Functions

A. TCAS Processor
(1)

General

The TPA-100A TCAS processor is the primary control unit in the CAS-100 system. The
processor has a combined computerized control system and L-band receiver/transmitter.
The operation of the TCAS system is controlled by TCAS software in the computer
control memory.
(2) TCAS Processor Description and Basic Functions (See Figure 4.)
The TCAS processor routinely reads and keeps the following own aircraft data:
(a) Own aircraft heading, pitch, roll, and radio altimeter input. This data with the
pressure altitude data lets TCAS find own aircraft position and flight path. The data
is used during tracking, RA and TA advisory, and traffic display computations.
(b) Own aircraft pressure altitude data received on the ARINC 429 data bus from the
Mode S transponder. The pressure altitude is input to the transponder from own
aircraft pressure altitude source. The pressure altitude is used to find own aircraft
altitude related to intruder reported altitude and own aircraft flight level altitudes.
(c) The mode control requests and traffic display control inputs from the Mode S
transponder through the ARINC 429 data bus. The Mode S transponder receives
this data from the transponder control panel (and may in the future also receive the
control input from the ground stations). This data is a factor in TCAS sensitivity level
determinations and traffic display formats.
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MAINTENANCE MANUAL
CAS-100 COLLISION AVOIDANCE SYSTEM
34-45-47
Page 39
1 Dec 2003