Originally Posted by
sudden twang
You should not rely on the GS for terrain clearance outside of 10 nm unless the chart states differently.
Many will follow the GS outside this distance.
IMHO you should cross other altitudes before 10 nm / FAP above the minimum charted altitudes.
You must not rely on the GS for terrain clearance outside of the
Final Approach Segment. The GS (ILS) obstacle assessment surfaces only extend to the FAP or FAF,
ICAO Doc 8168, Vol II (and also slightly into the intermediate segment), so the GS is not checked for obstacles or terrain outside of the final segment.
You can follow the GS outside of the final segment, but not use it to go below any charted minimum altitudes.