CAT II auto-coupled clarification
 

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Can someone clarify the first note below the table? I’d always understood that CAT II can be flown without the autopilot, so I just want to be clear on what’s being counted here.

Depends on the operator. Some only allow cat II with autoland.

My question is specifically from an EASA regulatory point of view rather than operator policy. Under EASA, CAT II approval itself doesn’t appear to mandate autoland, so I’m trying to understand what that note is referencing..

It's always best to reference latest revision of the regulations, as the example above is outdated.

For a Cat 2 approach with Cat D aircraft, the minimum RVR is 350m, if flown manually, or with AP disconnected before touchdown. If the approach is flown using autoland, then the minimum RVR drops down to 300m.

I understand the point you’re referring to, that’s the part explained in the second note below the table.

My question, though, is specifically about the autopilot requirement to 80% of DH, which isn’t clear to me from that note.

If you have a reference to the current version of the regulation, I’d really appreciate you sharing it

The 80% DH AP engagement may be a cary-though from previous requirements, particularly from CS AWO defining the equipment standard.
Previous regs limited Cat II manual to 400m, but if flown with AP a lower value (350?) could be used - provided the lower coupling height had been demonstrated.

The rationale was that the visual segment would have increased with reducing height - not necessarily true for all fog types.
The lower height involved AP accuracy, stability, and nose down failure recovery loss of height (may vary with auto trim up if autoland capable).
Another confusing intermixing of operational and equipment requirements.

The note essentially mandates the use of AP to 80% DH in order to claim the lower RVR; this was not as clear in previous regs.
Lower RVR with autoland may relate to failure cases (CS-AWO) together with the operational procedure associated with the failure - continue with manual landing or mandated GA; with potential for further confusion with AP failure at DH, but when using the lower RVR !

My understanding is that 80% was to allow the aircraft to descend below DA/DH to perceive a more accurate visual environment, before disconnection.

Also, we used to mandate that if a manual landing were to be performed (the aircraft doesn't know if it Cat III or CAVOK), then the auto-pilot must be disconnected by 80' (80%?). This was a legacy Airbus requirement applied to both A/B fleets and eventually removed.

The current EASA requirements are shown below. The title of the RVR columns in Table 3 (now Table 4) now reads "Auto-coupled or HUD to below DH". Clearly, the minima in the table are only available if the approach is flown with the autopilot coupled or a HUD used to "below DH".

ICAO Doc 9365 (Manual of All-Weather Operations) states that the term "below DH" means "continued use of the automatic flight control system down to a height which is not greater than 80 per cent of the applicable DH".


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