Honeywell
MK VI MK VIII EGPWS Installation Design Guide
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5.3.8 Category 8, Radio Altitude Input Select
The following table provides identification of the Radio Altitude type. The entry in the Radio Altitude Type corresponds
to a table that provides detailed information on the configuration. For example, the details for Radio Altitude Type #1 are
found in Table 5.3.8-1. ARINC 552, ALT 55 and digital ARINC 429 compatible Radio Altimeters are supported. ALT50
Radio Altimeters are not recommended due to the maximum 2000-foot operation. GPWS TSO-C92c requires Mode 1
alert thresholds up to 2450 feet radio altitude.
In this category, only the following signals are defined:
Radio Altitude source selection, input scaling, and associated validities.

Table 5.3.8: Radio Altitude Input Select

ID Radio Altitude
Type Description Software
Effectivity
EGPWS
Effectivity
(Table 5.3.8-x) MKVI MKVIII
0 0 Analog Radio Altitude (ARINC 552) -020 X X
1 1 Analog Radio Altitude (ALT 55) -020 X X
2 2 Digital Radio Altitude (ARINC 429) -020 X X
3 3 Analog Radio Altitude (RT-200/300) -020 X X
4 4 Analog Radio Altitude (KRA 405) -020 X X
251 251 Digital Radio Altitude (ARINC 429 via dual IOC
buses with DH/MDA) (Note 1,3) -020 N/A X
252 252 Digital Radio Altitude (ARINC 429 via dual IOC
buses) (Note 1,3) -020 N/A X
253 253 Digital Radio Altitude (ARINC 429 via dual IOC
buses with DH discrete) (Note 1) -020 N/A X
254 254 Digital Radio Altitude and MDA (ARINC 429
via dual IOC buses) (Notes 1, 2, 3) -020 N/A X
255 255 Digital Radio Altitude (ARINC 429 via dual IOC
buses) (Note 1, 3) -020 N/A X
Note 1: ID 251 - 255 may only be used in conjunction with other IOC bus selections for categories 2,6,9,10,11 and 12.
Note 2: ID 254 must be used in conjunction with Category 9 ID 254, since this provides Label 163 which determines from
bits 19-21 whether MDA or DH is displayed.
Note 3:ID 251, 252, 254 and 255 must not be us ed in conjunction with Category 4, ID 100 or 101 Altitude Callouts types.

Table 5.3.8-0: Radio Altitude Input Select Type 0 (ARINC 552)

SIGNAL CONNECTION REFERENCE SUMMARY DATA
Radio Altimeter #1 (+) = J1-64
(-) = J1-45
6.1.1
4.2.3.1
Format: ARINC 552 with Validity Flag
Input Type: Basic
Fault Designation: RADIO ALTIMETER FAULT
Validity: Radio Altitude Valid Discrete #1 (+28V)
PIN FUNCTION CONNECTION PIN TYPE CHANNEL DESIGNATION
REFERENCE
Polarity/Configuration References
Radio Altitude Validity
Discrete #1 (+28V)
J1-29 Input 28V_DISC_07 >+17V = Valid
<+4.4V = Invalid
6.6.1
4.2.7
DH Discrete (Gnd) J1-33 Input GND_DISC_11 Gnd = Below DH
<not> Gnd = Above DH
6.6.14
4.2.7