Originally Posted by
Gonzo
Once you get above 3.2 then CAT III approaches are not going to be flown (that’s the certification limit for most airliners (well, 3.25)).
When you look at FRA, there are two ILSes installed for the same runway, e.g. 25R - ILS Y and ILS Z. Different frequencies, GS angles 3 or 3.2 degrees, minimums for Cat I or Cat IIIb. In marginal weather you may expect ILS Z, otherwise Y.
Maybe LHR can have similar system, with descent angles 3 and 3.5 respectively?