According to Alan Warnes' interviews with the PAF senior personnel, he was shown radar track data which showed that the Su-30MKI was spiralling down and rapidly losing altitude, in addition to confirmation from the Viper that the missile had struck the aircraft. However, the PAF believe that the aircraft could have made it back to base, and this would certainly make it easier for the indians to cover up the kill and loss of the aircraft. I suspect the PAF has shared these details not only with Alan Warnes but others, especially maybe LM and the USAF.