I have no idea which or whether any system failed. All I said was that the TEsla S uses an integrated combination of the three systems. A boat uses radar , sonic sounding, and GPS, and still depends on a pilots skill at navigating by sight and sound (USe of lighthouses and view, water color and currents). What do you use in a plane in IFR? even when a bigass one is totally flying by wire, the pilot is there to make the final decisions.
As far as the S, Nobody is left with a belief that they can go into the "back seat" and watch a flick. Thats just wrong-headed