Good catch JASP! Momentum is huge!
In simplifying, I may have gone too far.
I originally wanted to state the definition as "The turn starts when the CM starts being deflected from it's inertial path. The turn ends when the CM is no longer being deflected from it's inertial path".
Turn end could be restated more positively as "The turn ends when the CM is allowed to follow it's inertial path." ("the inertial path" was removed for simplification. The inertial path is what happens when just falling downhill, not turning.)
OTOH, The beauty of including gravity is that the skier is always in one turn or another. What effect this has on the phases of the CSIA turn [1: completion to neutral, 2: neutral to fall-line 3: fall-line to completion] is that a new turn can be said to start immediately upon completion of the previous turn, regardless of the state of the edges, since gravity IS always having an effect. FYI: Completion is defined as releasing the CM from it's arc.
Interesting thought. Right now, I still prefer not to include gravity. I'll think about it - it actually may help people with their patience. The "patience turn" can make more sense. pros and cons to both sides I guess!