Originally Posted by
ana1936
We are trying to reconstruct an explanation for that map.
The last ping received was on the red arc. The aircraft was not necessarily on the arc prior to that time.
The aircraft was not necessarily at the western-most end of the arc at that time. The western end of the arc is probably where the pings would have been seen by next satellite west (but were not).
For all we know, the aircraft may have been on the ground at that time (but that implies the northern arc). Being on the ground may have resulted in two very similar pings tho.
I do not believe there has been anything that describes which arc earlier pings were on. Earlier would still have been mirrored north/south, but might (with some squinting of the eyes) given clues to which was it was moving after the last PSR contact.
Also keep in mind that there could have been some amount of time after the last ping that the aircraft continued to move.