Originally Posted by
MountainBear
If I understand the complaint correctly, the complaint is based upon a fundamental error. The 40 degree arc that is plotted on a map is a two dimensional representation of a three dimensional reality. There is no claim that the plane moved along the 40 degree arc in two dimensional space, only that it moved along the arc in three dimensional space. If every ping happened along the 40 degree arc all the means is that the plane held to the same altitude for 7 hours, nothing more.
Either that or I do not understand the criticism.
The 40 degree "arc" has nothing to do with the plane's altitude.
If you plot a great circle map centered on the sub-satellite point, the 40 degree "arc" will be a circle.
Anywhere along that circle, the satellite will be 40deg elevation.
As the satellite is just under 35800 miles above the earths surface, the altitude of the plane will make a small difference to the elevation angle, and the effective circle under the plane on the surface would be marginally smaller than the 40deg circle on the ground.
Another way to look at the "arc" or circle, if you draw an imaginaru line from the sub-satellite point, through the satellite, and out into space, then positioned your self on that line far out past the satellite, then looked back at the earth with the satellite in the middle, the 40 degree "arc" would appear to be a circle, and the circles would get smaller until at 90deg, it is just a point.