You cannot know the "speed" of the a/c point to point without knowing its route (Miles covered). This is where speculation gets out of control. My point is that the "line" between the last two reporting points is "straight", it may not have been, it hasn't been published if it is known. The line is itself speculation, onto which you have heaped additional (speed) speculation. What is "known" is the 3nm separation a/c from "flight path"
(per BEA).
Will, I fully agree with your post.
