Isca...
It was my post saying that line of sight was impossible to the rig. Let me rephrase with elaboration: the formula for distance to the horizon is sq root of altitude x 1.23 for Statute miles.
Elevation is additive, so the extra 12.3 SM the observer gains from deck elevation is added to the aircraft to horizon distance
Can you explain again, in English, what your coordinates mean? "Km of 387" is cryptic to me.
llne of sight from the rig, assuming a deck height of 100' and a target of 35,000' is 392 km, but the aeroplane would be observed to be ON THE HORIZON. And that would need to be a spectacular fire to be seen from almost 400km away.
Factoring the reports of the aircraft descending from 35,000' it becomes impossible due to the earth's curvature
The Chinese images are from the day after the event, hence within a few km of actual impact, assuming drift.
In any event, I did not read any emphasis in the purported email about the sighting to be so low as to be on the horizon.