VOR approach- when to descend from the FAF

Greg Esres wrote:
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.

Correct. The protected airspace for a VOR IAP overhead the VOR when
it's the FAF is 1 mile each side of the station. This width expands as
the aircraft departs the VOR/FAF. The maximum course change permitted
at the VOR/FAF is 30 degrees.

Descent shouldn't be made unless the pilot is tracking on course inbound
to the VOR/FAF. If he is on course as station passage occurs, and a
course change is required, a turn to intercept while commencing descent
is expected in the design of the criteria; i.e., the descent gradient is
calculated from the VOR/FAF, not from some imaginary post-facility point
of intercept, and the maneuver required to reintercept is minimal
assumming reasonable comptetency.