Causes
A Ukrainian led commission reported that the cause was human error and blamed the flight maneuvers by the crew as the major contributing factor to the crash. Leonid Berestov is quoted as saying "The careless actions of both crews in their formation flying led to a collision and crash."
Several faults were observed in the three test flights that took place before the accident flight, including flight control problems during the second flight and again during the third flight, on the day preceding the crash.
Read more about this topic: 1995 Antonov An-70 Prototype Crash