I bet the computers at DIA would pluck it out in a second or two. The
reason they didn't see the jet was they did not have the algorithm in
there to look for random debris.
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And it's entirely possible, even likely, that there was no satellite
in the right position at the right time. Satellites are not all that
useful for real time tracking of fast moving targets.
And just as possible the plane isn't even in the Southern Hemisphere....
There is not one spec of evidence we have been made aware of that
suggests the plane made it down there. Something is still fishy about
the whole thing.