Greetings,
No material describing such prediction (FTE), GPS or DME/DME or ILS sensors dont matter, what matters is that ANP(Boeing) EPU (Airbus) is smaller than RNP for that particular area.
In fact today the aircraft position doesnot matter at all, the hole concept is based on a sphere containing the aicraft, the aircraft position within the sphere dont matter, however the diameter of the sphere MUST always be smaller than the RNP, that can be visualized as a tube
