Rainboe It may benefit readers if you were to identify the references which support your statements and whether the recommendations are based on opinion or fact.
”The rule book says …”
The background to ‘European’ Cat 3 operations is given in CS AWO 300 – aircraft certification.
CS-AWO 321 specifies the equipment required for a range of operations, generally subdivided by equipment capability and the decision height.
Thus for 50 ft DH, autoland in not always necessary, but where fitted, and if the system fails below DH then a manual landing can be made in particular circumstances. Whether manual landing can or should be approved in these circumstance is debatable (original thread question) and in practice involves both aircraft and operational certification – not just pilots or engineers beliefs. Operators may impose additional, more stringent operating restrictions.
RVR limits (and other caveats) are given EU-OPS1 (E) – operational certification.
Cat 3a operations are not normally allowed below 200m, but there is an option for fail passive operations in Cat 3b – DH 50ft in 150m (Appendix 1 (Old) to OPS 1.430 table 8). Here, there is opportunity for confusion between the ‘older’ ICAO terminology and the new, rapidly developing equipment capabilities catered for in the new rules – i.e. a muddle (IMHO).
The visual references for each operation Cat 1 – Cat 3 vary. The actual visual requirements have been determined by the required piloting task e.g. Cat 1 may involve ‘significant’ lateral manoeuvres, whereas the equipment standard required for Cat3 should ensure that a minimum if any lateral manoeuvre being required. Most of these aspects were determined by research which involved manual landings in actual conditions. This is documented in “The Economic Cat 3 Programme 1975-80” RAE report TR81025, also in TR 79130 “Manual Landings in Fog”.
Thus your statement “… trying to manually land and rollout at 200metres visibility and high speed is dodgy…” should perhaps be qualified by aircraft type and landing speed. CS-AWO recognises that not all types are suitable for manual landing in the lowest visibilities.