You can't judge by the victim's film how close the plane was to the round going off. You need to see the shooter's film, as it's his FE on which a 'hit' is determined. The inherent lag means you see the tank shoot later than he actually did.
Just as on many of my films enemy bullets strike empty space behind my plane, yet I am hit. That's not a result of a bug, that's just the effect of combined lag.
Ok so lets account for that, perfect scenario directly over the blast

Went an flew a storch over there got the alt, subtracted it from my alt its still 143 ft distance from the ground to my plane, I would like to know how the blast is modelled, personally speaking I think its a cube and anything in that cube is dead regardless of its position relative to the centre, I had guys bombing me in a GV an not even being close and an instant death. 143 ft is a bit much sorry

how much explosive can you put in an 85mm shell that will when fired into the ground produce an instant death to an aircraft 143 ft away from it, seems quite far fetched to me.
Couldn't find any info on the HE shells the 85mm fired that would be helpful if anyone knew that info.