User's Manual
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
TCAS 3000 Traffic Alert and Collision Avoidance System
34−43−23
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Page 1−51
15 Dec 2005
5. System Operation
The principal modes of operation and display features of the TCAS 3000 are discussed in the
paragraphs that follow. In−flight procedures with display examples are contained in the TCAS
Pilot’s Manual, ACSS Publication No. C28−3841−005.
A. Operational Modes
The TCAS 3000 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.
(1) 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:
(a) 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.
(b) 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.