there is no indication that a beyond GS figure is used in any performance calculation.
of course it's not used as it would result in a longer ALD. That's the whole point here. Not much logic is really required to understand the difference between the certification data and real life performance. That's what this is all bout. Not all the GS antennas and PAPI are located exactly 305 m beyond the THR and if located further away it must be taken into account as one is bound to follow the GS and when transitioned to visual continue to aim for the TD point. Following your logic neither there's a mandatory requirement to use beyond THR value. EU OPS ONLY prescribes 50 ft for RLD at the dispatch phase in flight it's a different story altogether. Exactly the same problem is faced with certified actual landing distance used for certification thus slowly but surely operators and manufacturers recognized that those figures are pretty much useless in real life. Guess what, they came up with operational landing distances almost doubling the actual ones. Healthy skepticism will prove useful eventually whereas blindly believing it's all been taken care of might bite one in the a&se.
