User's Manual Part 2

T
2
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.
6--10
Figure 6--4. Typical RAD/ALT Status Page
The first information line (line 3) of the RAD/ALT STATUS page indicates which
of the two radio altimeter ports is being used by the T
2
CAS computer. The
T
2
CAS computer attempts to use radio altimeter No. 1 first. If it determines this
input is invalid, it automatically switches to radio altimeter No. 2.
The current status of the two radio altimeter ports is displayed on lines 5 and 6.
If a signal is valid, the radio altitude value is displayed in either “FT” for English
type altime ters, or “M” for Metric type altimeters.
If one of the radio altitude signals is determined to be invalid, the altitude value is
replaced by INACT. Radio altitude INACT indicates the radio altimeter has failed,
is not powered, or is not connected.
The radio altimeter input is determined to be invalid if, for an analog radio
altimeter input, +28 Vdc valid is not present at T
2
CAS CU pin RMP--2K for Radio
Alt #1 or pin RMP--3C for Radio Alt #2, or for a digital radio altimeter input, the
sign status matrix (SSM) of the radio altimeter output indicates not valid or no
data is present on the digital bus.
If the radio altimeter output is greater than 2200 feet (source is valid, but data is
invalid), the radio altitude value is replaced by OVR RNG.
When both radio altitude sources are invalid, line 3 is blank.
(e) Transponder (XPDR) Status Page
Selection of code 0003 displays the XPDR Status page, Figure 6--5. This page
displays data for the transponder selected at the time the extended test mode
was entered.