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MINIMA REQUIREMENTS – WHAT YOU NEED TO SEE
VISIBILITY REQUIREMENTS AT MINIMA
SVR (slant visual range) can vary greatly (less or more) from RVR
(runway visual range). SVR cannot be measured. SVR is more often
(90% of cases) less than RVR.
RVR is measured when vis is below 500m. End zone measurement is
not required unless mid zone is not available. For CAT 3b operations all
zones are required.
WHAT TO SEE
CAT 1: at minima, a portion of the approach lights in view then - the
threshold lights should come into view shortly. If there is no approach
lighting then the threshold lights should be in view at the CAT 1 minima
to continue.
CAT 2: at DH, a substantial span of the approach lights commencing
midway between the first 2 crossbars and extending to the threshold
CAT 3: at DH, TDZ or other runway lights appropriate to the DH must be
visible
SYSTEM INFORMATION
FAILURE AND SYSTEM DEFINITIONS
ALERT HEIGHT (Airbus definition, FCOM 4.05.70 P4)
“The alert height is the height above touchdown, above which a CAT 3
autoland would be discontinued and a missed approach executed, if a
failure occurred in either the aircraft system or the relevant ground
equipment. Below the alert height, if such a failure occurs, the flare,
touchdown and rollout may be accomplished by the remaining automatic
system”.
Alert height applies to CAT 3 only.
The alert height is associated with both the autopilot and the ILS beams.
If the pilot can continue by visual reference (CAT 1 or better) then a
manual landing can still be completed. The alert height relates to
equipment, not procedures.
The alert height for the A330 is 200’ RA
FAIL OPERATIONAL: Below the alert height, a system failure occurs
which still allows the automatic landing to be completed with the
remaining systems. CAT 3 approach must be fail operational. For a CAT
3 DUAL approach, a failure below the alert height generally does not
“LOWVISI” (OCT 07) NOT AN OFFICIAL DOCUMENT
PAGE 2
require a go-around. Fail operational is associated with CAT 3 DUAL on
the FMA.
FAIL PASSIVE: Below the alert height, a system failure occurs which
results in the aircraft maintaining a stable flight state (ie. flight path, trim,
attitude, etc) but autoland is not possible – a manual landing can be
completed if there is enough visibility to flare, touchdown and rollout. A
manual go-around is still an option – especially if visual cues are
inadequate, no matter what RVR is reported. CAT 2 approach can be fail
passive (a manual landing and rollout can be completed – although this
is not to be planned.) The failure case applies when the fault occurs
when ON the approach and not prior. Fail passive is associated with
CAT 3 SINGLE or CAT 2 on the FMA.
For anti-skid and nosewheel steering failures, disconnect the AP and
perform the rollout manually if visibility permits.
TECHNICAL
The automatic ‘retard’ call is 20’ for manual landing and 10’ for autoland.
AUTOMATIC RA CALLS
200’ CAT 3 DUAL alert height
100’ CAT 3 DUAL no DH
SYSTEM FAILURES
SYSTEM FAILURES
With a failure there are only 3 options:
- continue to planned minima
- revert to a higher minima
- go-around
AP engagement or re-engagement below 1,000’ RA is not permitted.
“It is considered preferable to discontinue an approach rather than
attempt corrective following a system failure or warning below 1,000’ RA”
Continuation of approach following a failure can be done if:
- all ECAM actions are complete
- the failure does not affect the minima (no reversion)
- the failure requires reversion to a higher minima and the weather is
suitable for the higher minima and the decision to revert is completed
by 1,000’ HAT.
If A/THR has failed, try using the other AP and re-engaging A/THR
(above 1,000’ RA only)
For true low vis ops (ie. Vis below CAT 1) - a go around must be
performed in the case of:
- AP OFF (cavalry charge)
- Downgrading of capability (clic clic clic), eg. loss of CAT 2 or CAT 3
- Any AMBER caution or RED warning
- Any FLAG (flag on STBY ATT IND now OK – can fail)
- ALPHA FLOOR activation
- ENGINE failure and ECAM actions not complete before 1,000’ HAT
- no LAND GREEN at 350’ RA
- LOC/GS excessive deviation
- below 200’ RA: AUTOLAND warning light
When the weather is at or above CAT 1, the pilot can disconnect the AP
if a system fault occurs and fly manually to the CAT 1 minima (or visual
approach if available) as usual.
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