Greg Esres wrote:

Once you're established on a published segment you can descend to
the appropriate altitude for that segment.

Agreed, but the *pilot* must know when he's established on a segment
of the approach. A random controller is not qualified to determine
that.

There's a question here about the clearance; either ATC issued an
improper clearance or it was quoted incorrectly. But ATC did issue an
altitude to maintain until established, 2000 feet.


I'm not questioning the clearance, but I'm questioning whether the
pilot should rely on ATC's interpretation of what it means to be
established.

Bad example. TWA514 was not vectored for the approach, they simply
descended below the published altitude for their route.

No, they descended to published altitudes BEFORE they reached the
point where those altitudes applied. They were not on a "black line".

I think this example is appropriate because

1) involves the definition of "established", and
2) involves confusion between who is providing terrain clearance.

You're spot on. See example #3 in AIM 5-9-4.