[O.B.Left]

Can you set up at impact fix with everything on plane? Yes.
There's the answer.
The left arm is not on plane (#3 accum) by definition.
The right forearm is, with a little bend left in the elbow. (Impact is to occur before maximum extension.)
The definition of the Flying Wedges.

If the right shoulder does not move down on plane, it must move somewhere else, which requires compensation.
ndwolfe is not moving the right shoulder down the plane angle. It could be the right hip is in the way.

Thanks Loren. I hate to belabour the point, but when you say "everything" I dont think you are including the right shoulder to which ndwolfe alludes. You are of course, correct in that the right shoulder should not be on the inclined plane at Fix. In Startdown perhaps, if you so choose. Its seems as if the Right Forearm and the Right Shoulder cant travel the inclined plane together if there is any elbow bend. They may take turns on it but not together.

You could I suppose get the right shoulder and the RFFW on the inclined plane at Fix but only with a perfectly straight right arm. A death move or should I say death alignment, unless you are putting maybe.