Flying for a large somewhat orange UK operator I have long wondered why the "local" policy was to check the documentation to see whether a given rwy was approved for Cat IIIb and then use the Cat I plate to execute the approach.
One of the prerequisites for using any plate is that it only "valid" or in other words safe if you stay within the "boundaries" defined on the plate. A cat I ILS plate by definition only provides obstacle clearance if you stay inside the limits. Ie. if the minima is 200ft, the missed app. proc. only provides obstacle clearance if you initiate your missed app. at DA and don't sink through more than..... is it 30 ft ??
My point is, if you go down to ie. 50 DH and then carry out a go-around you have effectively busted the foundation of the plate, and as I understand you are not guaranteed obstacle clearance.
Now I know this is a bit longhaired, but as I understand it the largest operator in Scandinavia has a proc.for this "G/A blw. published minima" and they use and brief the engine out proc. for that scenario.
OY
Ps: We just very recently got Airline tailored plates from jepp, so it is not really an issue anymore, still I wonder
