The main point on this is the aircraft was certainly not going into Belgorod, it was outbound, and therefore cannot have had "POW's" on board. The timing errors in this rough "back of envelope" estimate using time offsets probably put the location marked below to the SW of the actual position of the strike, but in all cases, the plane is flying ENE, away from Belgorod. This analysis gives a very high speed impact, higher than I would expect to have occurred, but it is in the right rough order of merit.
That assumes that the Il-76 had no warning. My understanding is that this aircraft type is equipped with RWR. If (as been theorised) this was a Ukranian SAM ambush, then, even against a patriot, the flight crew should still have seen the search radar some minutes before being hit. Given that, I'm not sure that the direction of flight can tell you with confidence where the aircraft was flying from.