The airplane impacted into a 7,800-ft mountain at the 6,400-ft level, approximately 1 mile north of a planned route. The pilot had flown the course over 100 times during the previous 6 months. Witnesses reported that instrument meteorological conditions prevailed over the mountainous flight route. The pilot had on previous occasions given dual instrument flight instruction to passengers during air taxi cargo flights in IMC. Evidence shows that both occupants survived the crash; the forensic pathologist who performed the autopsies reported that the occupants might have survived if they had been promptly rescued. An ELT signal was first heard at 1815. At 1900 the FAA received a telephone call from a concerned relative of the pilot. At 1956 a Navy pilot reported that he had picked up a mayday call. The Rescue Coordination Center at Scott AFB opened the incident case for the accident airplane following receipt of notification from the FAA at 2001. The wreckage was found the following day at 1735.