What happened
On July 31, 2020, at approximately 0827 Alaska daylight time, a de Havill and DHC-2 (Beaver), registration N4982U, and a Piper PA-12, registration N2587M, were involved in a midair collision near Soldotna, Alaska. The DHC-2 was operating as a Part 135 on-demand charter flight, traveling northwest from Longmere Lake toward the west side of Cook Inlet. The PA-12 was operating as a Part 91 personal flight, traveling northeast from Soldotna Airport toward Fairbanks.
The two aircraft were flying at approximately 1,175 feet mean sea level when they collided about 2.5 miles northeast of the Soldotna airport. A witness at the scene reported that the PA-12 struck the left side of the DHC-2's fuselage toward the rear. Following the impact, the DHC-2's left wing separated, and the aircraft entered an uncontrolled, descending spiral. The collision resulted in 6 fatal injuries, including the pilot of the PA-12 and the pilot and five passengers aboard the DHC-2.
The investigation
An investigation into the wreckage revealed that the DHC-2's main wreckage was heavily fragmented in a wooded residential area, while the PA-12 wreckage was located approximately 600 feet east of the DHC-2. The investigation included a cockpit visibility study and an aircraft performance study using ADS-B and radar data.
The visibility study determined that the PA-12 was unobscured and visible to the DHC-2 pilot for 53 seconds prior to the collision. The DHC-2 was also visible to the PA-12 pilot for 28.3 seconds before the impact. Environmental factors included a thin cloud ceiling and a sun position that required the PA-12 pilot to look toward the sun to potentially spot the DHC-2. Additionally, the investigation found that the pilot of the PA-12 had been denied medical certification in 2012 due to severe glaucoma, which caused irreversible optic nerve damage and visual field defects.
Findings
- The pilot of the PA-12 was flying with a known severe vision deficiency.
- The DHC-2 was not equipped with any traffic awareness equipment.
- The PA-12 was equipped with ADS-B Out and In, but the investigation could not determine if an alert was generated.
- The lack of a requirement for airborne traffic advisory systems with aural alerting among Part 135 operators contributed to the accident.