User's Manual Part 1

T
2
CAS / Part No. 9000000
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
34-43-20
15 Feb 2003
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1--60
5. System Operation
A. TCAS Operation
The principal modes of operation and display features of the TCAS function are
discussed in the paragraphs that follow. In--flight procedures with display examples are
contained in the T
2
CAS Pilot’s Manual, ACSS Publication No. 8000264--001.
(1) Operational Modes
The TCAS function can operate in several different modes, depending on control
panel selection. Several control panels are available. Only the ACSS single Mode S
control panel is discussed. Other control panels provide similar features.
Four switches directly affect the TCAS operational mode: TCAS/XPDR mode
selector, TA DSPLY selector, ALT RPTG selector, and TCAS TEST switch. To
distinguish the modes that provide TCAS advisories from those that do not, the
operational modes are discussed under TCAS modes and non--TCAS modes. The
non--TCAS modes are annunciated TCAS OFF at the center of the display.
The extended test mode is mentioned for reference. A detailed description of its use
can be found in the FAULT ISOLATION section.
(a) TCAS Modes
The TA/RA and the TA--only modes are the two TCAS operational modes. The
TA/RA mode gives traffic information and warnings of hazardous traffic conflicts,
while the TA mode gives only traffic information. A third mode, the TEST mode,
can be temporarily activated from any mode including standby (STBY). The
TEST mode does not inhibit the generation of advisories. Functions available in
the operational and test modes are as follows:
1
TA/RA Mode
This mode is the normal operation mode providing full TCAS coverage. In
this mode, TCAS tracks all aircraft in the surrounding airspace and
generates traffic advisories or resolution advisories, as the situation requires.
Figure 1-- 3 contrasts the airspace covered for each kind of advisory.
For normal TA/RA operation, the TA/DSPLY selector must be set to AUTO or
ON and the ALT/RPTG selector must be set to 1 or 2.
2
TA Mode
The TA mode provides only surveillance of the surrounding airspace. In this
mode, TCAS tracks all proximate aircraft and generates traffic advisories; no
resolution advisories are issued in this mode.
The flight crew uses the TA--only mode when resolution advisories would be
a nuisance, or when flying over an area where only TCAS surveillance is
allowed. Also, the system automatically selects this mode when the aircraft
is flying under 1000 feet above ground level (AGL).
The TA mode is annunciated TA ONLY at the upper left corner of the display.