Peter wrote:
For what this is worth, on the European IR one is not supposed to
descend (from the platform altitude) unless one is established within
5 degrees of the track. I don't know the reference but this is what I
was always taught. To me, it makes sense and the only time I would
deviate from it would be


ICAO standards for "established" are 1/2 scale deflection. The US
doesn't have a similar definition, unfortunately. Sam Spade was
arguing that, over the VOR, that standard doesn't have much meaning.
For a staying-in-protected-airspace point of view, I'm sure he's
correct.