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Old 21st Mar 2022, 16:07
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safetypee
 
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FD, Cat II minima
As per ICAO doc 9365 Manual of all weather operations.
EASA - ongoing review of AWO ?

Re #3, is the interpretation of the diagram as showing an RVR of 217m equating to a SVR of 250m. If so minor confusion as RVR only given in 10s
Although geometrically accurate, it only applies at a single instant; DH=100ft. Operationally the pilot needs to see the required visual segment above DH with sufficient time to make a decision (2 sec ~ +20 ft at 10ft/sec), which would imply a higher RVR, hence 300m minima.

Also, note that many fogs, particularly in Cat II, do not have a linear relationship between SVR and RVR, e.g after acquiring the required vis segment it ‘opens’ rapidly with decreasing altitude, like exiting very low cloud - tight decision, easy landing.
Alternatively a ‘closing’ segment where the vis segment reduces with decreasing altitude like entering thicker ground fog - easier decision, but could be difficult for manual landing, yet for the same reported RVR.

ICAO doc 9365 e reader @ https://elibrary.icao.int/reader/229...ductType=ebook
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