Continuing the discussion from How To Find This Point With Object Snap?:

@EricM - If you’re looking to find the intersection of a tracking line and a CPlane, you can do this in V6, using SmartTrack and its origin snap point (new in WIP). However, with an arbitrary plane surface object, you still can’t without using some construction geometry as there is no implied curve-surface intersection osnap.

Edit: here is a video with your posted file with circles from the original thread.

–Mitch