It’s not that far for the sphere to significantly come into play. But you can recheck the numbers here:
+++++
4 hours. 500 miles per hour. 2000 miles. 2000/24000 = 1/12
1/12 * 360 = 30 degrees. I don’t think a 30 degree arc on a globe would look as straight as the plot.
But maybe the are using some transformation that plots arcs as straight lines. If that is possible.
You are right. Something doesn’t look right.
I looked at this again last night and the only way the Inmarsat arcs work with the autopilot is if the plane was put on autopilot deadheading to New Amsterdam Island shortly after turning south for about 4.5 hours —
BUT then in order to hit that final arc it would have had to come off autopilot and that heading with about an hour of fuel left. It’s at that point that it would have to turn to the east toward Perth to hit that final Inmarsat arc and the new search area.
Whether he then put it back on autopilot after making those course corrections with an hour left, who knows, but that’s what they must be calling “being on autopilot”.