Thales 421 - Check Alarm Limits and Alarm Delays

LLZ 421
Operation and Maintenance Alignment Procedure LLZ−2F (LPD)
ILS 420
8−19Ed. 07.08
SOAC
8.4.5 Check Alarm Limits and Alarm Delays
NOTE: If upper limit is equal to lower limit, executive monitoring is not available.
8.4.5.1 Executive Alarm Limits
a) Open dialog ’Monitor 1 − Executive Alarm Limits’ and open dialog ’Monitor 2 − Executive Alarm
Limits’ (for MCS: dialogs ’Monitor 1/2 − Limits: Current Executive Data’).
b) Check that RF level alarm limits for all monitors are set to: 90 % (lower limit) and 110 % (upper limit).
c) Check that SDM alarm limits for all monitors are set to: 38 % (lower limit) and 42 % (upper limit).
d) Check that POS DDM alarm limits for all monitors are set to:
–0.9 % (lower limit) and +0.9 % (upper limit)
NOTE: Used for CAT III only, CAT I and CAT II require other values, see section 8.8.
e) Check that CRS WIDTH DDM alarm limits for all monitors are set to:
–2.6 % (lower limit) and +2.6 % (upper limit) of actual measured value;
example for 15.5 %: 18.1 % (upper limit) and 12.9 % (lower limit)
f) Check that CLR WIDTH DDM alarm limits for all monitors are set to:
−4 % (lower limit) and +4 % (upper limit) of the actual measured value.
g) Check that Ident AM alarm limits for all monitors are set to:
−2 % (lower limit) and +2 % (upper limit) of the actual measured value.
h) Check that Alarm delay time is set to: CAT I: 10 s; CAT II: 5 s; CAT III: 2 s (prefer. 1 s); NF: 20 s.
8.4.5.2 Far Field Alarm Limits
a) Open dialog ’Monitor 1 − Far Field Alarm Limits’ and dialog ’Monitor 2 − Far Field Alarm Limits’
(for MCS: dialogs ’Monitor 1/2 − Limits: Current Far Field Data’).
b) Check that RF level alarm limits for all monitors are set to: 71 % (lower limit) and 129 % (upper limit)
c) Check that SDM alarm limits for all monitors are set to: 38 % (lower limit) and 42 % (upper limit).
d) Check that POS DDM alarm limits for all monitors are set to:
–0.9 % (lower limit) and +0.9 % (upper limit)
NOTE: Used for CAT III only, CAT I and CAT II require other values, see section 8.8. The alarm limits
are only available if an integrated FFM is installed.
8.4.5.3 Standby Alarm Limits
a) Open dialog ’Monitor 1 − Standby Alarm Limits’ and dialog ’Monitor 2 − Standby Alarm Limits’
(for MCS: dialogs ’Monitor 1/2 − Limits: Current Standby Data’).
b) Check that RF level alarm limits for all monitors are set to: 90 % (lower limit) and 110 % (upper limit)
c) Check that SDM alarm limits for all monitors are set to: 38 % (lower limit) and 42 % (upper limit).
d) Check that POS DDM alarm limits for all monitors are set to:
–0.9 % (lower limit) and +0.9 % (upper limit)
NOTE: Used for CAT III only, CAT I and CAT II require other values, see section 8.8.
e) Check that CRS WIDTH DDM alarm limits for all monitors are set to:
–2.6 % (lower limit) and +2.6 % (upper limit) of actual measured value;
example for 15.5 %: 18.1 % (upper limit) and 12.9 % (lower limit)
f) Check that CLR WIDTH DDM alarm limits for all monitors are set to:
−4 % (lower limit) and +4 % (upper limit) of the actual measured value.
REMARK: Check pre−alarm limits. If need be adjust to 80 % of alarm limit value (recommended).