Originally Posted by
galaxy flyer
The OP's proposition was to descent to "platform" altitude upon receipt of the approach clearance--which exactly what TW 514 did, such as a platform existed.
Again, no, it is not. "platform" altitude is an unofficial term which apparently may mean different things to different people, and it has absolutely no meaning in the context of US TERPS. It is significant that aterpster, one of the more knowledgeable people in the US about TERPS issues had never heard of "Platform Altitude".
There are some pretty broad clues what the OP meant when he said "platform altitude". I'll quote them for you. The first is the thread title:
'Descend to
MSA when "cleared approach"'
Then in the original post, tha actual question being asked:
" Can you legally descend to the
MSA before you are established? "
Did you notice that "MSA" keeps popping up?
That’s what the question is about; descending to
MSA and that's not what caused TWA 561 to crash. They descended
below MSA to the
intermediate approach altitude. You'll notice that nowhere does the OP suggest or asking about descending to an intermediate altitude prior to being established on that intermediate approach segment.
Originally Posted by
galaxy flyer
And when would suggest they left 3300 feet? Besides, TERPS does not authorize the MSA as an operational altitude and it was trained that way, in any case.
GF
I never claimed it was legal to descend to MSA in the US. As others have pointed out it's not a procedural altitude
in the US I'm only saying that if they had descended to the relevant MSA and maintained that altitude until established on the approach, (which is what is being proposed by the OP) they would not have crashed. That's not a trivial distinction.