Yes, it looks like it does just estimate the great circle route. The lines are all dashed for the planes over the ocean, starting a few hundred miles offshore.

Yes, it looks like it does just estimate the great circle route. The lines are all dashed for the planes over the ocean, starting a few hundred miles offshore. This may change soon -- at least for the North Atlantic -- now that Aireon is using satellites to pick up ADS-B data. It's just a question of whether or not this info gets included in the FAA's ASDI feed.