What happened
The incident occurred during daytime operations under Visual Meteorological Conditions (VMC). Visibility was reported at approximately 30 miles, with light winds from the west aloft as noted by the pilot. The collision took place at an altitude of 4,500 feet mean sea level (MSL), occurring within approximately 15 degrees of a head-on trajectory.
En route recorded data revealed that N39516 was flying on a true course of 180 degrees, while N1162N was on a true course of 346 degrees. Accounting for the magnetic variation of approximately 7 degrees and 25 minutes east, the approximate magnetic courses were 173 degrees for N39516 and 339 degrees for N1162N.
Regulations under FAR 91.109 dictate that aircraft flying on specific headings should maintain odd thousand-foot altitudes plus 500 feet. The data indicated a deviation from these standard separation protocols, leading to the catastrophic intersection of flight paths. The left horizontal stabilator of N39516 penetrated the cabin of N1162N, resulting in 1 fatal injury to the solo pilot aboard that aircraft.
The investigation
Post-impact examination revealed that the stabilator of N39516 had separated from its vertical fin. This structural failure caused the aircraft to enter an uncontrolled descent. Following the collision, N39516 was completely consumed by a post-crash fire, destroying much of the physical evidence on board.
Findings
The primary factor in this accident was the loss of separation between the two aircraft due to non-compliance with altitude assignment rules for their respective headings. The structural failure of N39516's stabilator during the impact exacerbated the outcome, leading to the total destruction of that airframe and the fatal injury of the pilot in the other aircraft.