gents, thanks a lot for your input. As a few of you found out, has to be (at least following the EU Ops) below 4.5° , and here is what Mr Airbus says:
“A320 family aircraft are certified for approach with a flight path angle up to 4.5° excluded.
Approaches with a glide slope angle from 4.5° and up to 5.5° are categorized as Steep Approaches in the EU OPS regulation.
According to Appendix 1 of EU OPS 1.515 (a)(3) “Steep Approach Procedures”, it is not permitted to perform an approach with a glide slope angle equal to or greater than 4.5° without an Authority approval.
The Steep Approach Landing is not a standard procedure on Airbus aircraft and is consequently not documented in the standard Aircraft Flight Manual (AFM). Steep Approach Landings are only certified on A318, and only after modifications embodiment on the aircraft.”
Happy to read we may design a 4.2° along our terrain...