User's Manual Part 1

T
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CAS / Part No. 9000000
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
34-43-20
15 Feb 2003
Use or disclosure of information on this page is subject to the restrictions in the proprietary notice of this document.
1--64
(d) VSI Scale Overlays
During a resolution advisory, red and green bands overlay the VSI scale. The
red band indicates what vertical speed range is to be avoided by the pilot
(prohibited vertical speed). The green band indicates the vertical speed the pilot
is to attain to achieve safe separation from a threat aircraft (recommended
vertical speed). The red/green band reflects the RA in progress and acts as a
vertical speed advisory for the pilot.
(e) Reference Graphics and Annunciations
A white airplane symbol is displayed in the lower center of the VSI representing
the aircraft own position. A white range ring made up of 12 dots, each
corresponding to a normal clock position, is included. The range ring surrounds
the airplane with a radius of 2 nautical miles and is intended to assist in
interpreting TCAS traffic information.
The scale of the VSI display is 6.0 nautical miles to the top display edge of the
VSI (ahead of the aircraft), 4 miles to the left and right edges, and 2.5 nautical
miles to the bottom (behind the aircraft).
Annunciations in white letters serve as a reminder of the current operation mode.
They include TCAS OFF, TA only and RA only. Fault annunciations in amber
letters replace the mode annunciations in case of system failure. They include
TCAS FAIL, RA FAIL, VSI FAIL, and TA FAIL (traffic display failure). Figure 1--14
shows a typical failure display.
(3) Aural Messages
The TCAS generates aural alerts or messages announced over the aircraft audio
system. These messages accompany the visual TA or RA display and are softened
or strengthened, depending on the urgency of the situation. The TCAS audio level is
preset and is not adjustable by the aircrew.
If a logic change occurs before a message is completed and a new message is
initiated, the original alert is terminated and the new alert announced immediately.
(a) Requirements and Limitations
The following is a list of the require ments and limitations for issuing an aural
advisory by the T
2
CAS Computer Unit:
1
Voice announcements are inhibited below 500 feet above ground level
(AGL).
2
The CANCEL BUTTON, which is reserved for future use on the --XX001
T
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CAS CUs only, halts voice announcements a fter the CANCEL BUTTON is
activated. An aural advisory in progress is terminated and not repeated after
deactivation of the CANCEL BUTTON.