IMPROPER PLANNING/DECISION BY THE PILOTS OF BOTH AIRCRAFT, AND THE MITSUBISHI PILOT'S MISJUDGMENT OF HIS POSITION, WHILE ATTEMPTING TO FLY FORMATION AT NIGHT WITH AN AIRCRAFT THAT DID NOT HAVE ALL NAVIGATION LIGHTS OPERATIVE. FACTORS RELATED TO THE ACCIDENT WERE: BOTH PILOT'S LACK OF TRAINING IN THE TYPE OF OPERATION, DARKNESS, INOPERATIVE NAVIGATION (TAIL) LIGHT ON THE CESSNA 310, AND THE LACK OF VISUAL PERCEPTION THAT WOULD HAVE BEEN AVAILABLE TO THE MITSUBISHI PILOT.