getting to grips with CAT II CAT III operations(10)

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Additional information on pilot's eye position
The pilots must realize the importance of eye position during low visibility approaches and landing. A too-low seat adjustment may greatly reduce the visual segment. When the eye reference position is lower than intended, the already short visual segment is further reduced by the cut-off angle of the glareshield or nose.
Airbus aircraft are equipped with an eye position indicating device. The optimum eye position is obtained when the pilot sees the red indicator ball covering the white ball.
Additional information on landing lights
Use of landing lights at night in low visibility can be detrimental to the acquisition of visual references. Reflected lights from water droplets or snow may actually reduce visibility. Landing lights would therefore not normally be used in Category III weather conditions.
VISUAL SEGMENT AT DH=100ft WITH RVR 350m (TYPICAL CAT II)
Figure 2.6

VISUAL SEGMENT AT DH=50ft WITH RVR 200m (TYPICAL CAT III A)
Figure 2.7

2.5 FAIL-PASSIVE AUTOMATIC LANDING SYSTEM
An automatic landing system is fail-passive if, in the event of a failure, there is no significant out-of-trim condition or deviation of flight path or attitude but the landing is not completed automatically. For a fail-passive automatic landing system the pilot assumes control of the aircraft after a failure (JAA).
On Airbus aircraft since the A320, fail-passive capability is announced by the display of CAT 3 SINGLE on the PFD.
Figure 2.8 PFD on A340

2.6 FAIL-OPERATIONAL AUTOMATIC LANDING SYSTEM
An automatic landing system is fail-operational if, in the event of a failure below alert height, the approach, the flare and landing can be completed by the remaining part of the automatic system. In the event of failure, the automatic landing system will operate as a fail-passive system (JAA).
On Airbus aircraft since the A320, fail operational capability is announced by the display of CAT 3 DUAL on the PFD.
Figure 2.9 PFD on A340

2.7 MINIMUM APPROACH BREAK-OFF HEIGHT
The Minimum Approach Break-off Height (MABH) is the lowest height above the ground, measured by radio-altimeter, such that if a missed approach is initiated without external references:
.  in normal operation, the aircraft does not touch the ground during the procedure ;
.  with an engine failure during a missed approach, it can be demonstrated that taking this failure probability, an accident is extremely improbable.
This definition is not considered by the FAA and is abandoned by JAA following the harmonization process of the AWO regulations.
The MABH will remain indicated in some Airbus AFM (except FAA AFM).
For some Airbus type the MABH is replaced by an indication of the minimum DH and for more recent certifications the MABH will be replaced in the procedure section of the AFM by an indication of the altitude loss during automatic go around.
　
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