Not necessarily. The distance from the satellite shown may be inferred from a single ping, based on the strength of the signal. This places it on the arc.
The center portion of the arc is removed by local radar or other source.
The left portion of the arc is ruled out because the plane at max speed couldn't possibly get from its last radar location to that far away.
Therefore, the red arc was its set of potential locations during the last ping. It should be noted that the path the aircraft took need not follow that arc the whole time. Only it means that the aircraft intersected the red portion at the time of that ping.