Investigation Summary
The collision occurred at approximately 1,175 feet MSL where the flight paths of the two aircraft converged. The DHC-2 was climbing northwest after departing Longmere Lake, while the PA-12 was traveling northeast from Soldotna Airport. A visibility study conducted by the NTSB determined that the aircraft were within each other's unobstructed field of view for 53 seconds (for the DHC-2 pilot) and 28 seconds (for the PA-12 pilot), well above the 12.5-second threshold required for evasive action. However, the PA-12 pilot was flying toward the sun against a complex background, and his vision was severely compromised by glaucoma, for which he had been denied medical certification in 2012. The DHC-2 was not equipped with any ADS-B equipment (neither Out nor In), which prevented the PA-12's traffic advisory system from providing an automated alert of the approaching Beaver.
Final Conclusions
The NTSB determined the probable cause was the failure of both pilots to see and avoid the other airplane. Contributing factors included the PA-12 pilot's decision to fly with a severe vision deficiency and the FAA's lack of requirements for airborne traffic advisory systems (ATAS) with aural alerting for Part 135 passenger-carrying operations.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
High Adventure Air Charter N4982U — de Havilland DHC-2 Beaver · N4982U
Private N2587M — Piper PA-12 Super Cruiser · N2587M
Crew Experience
Pilot
The pilot held a commercial pilot certificate and a first-class medical certificate. He had extensive experience in the DHC-2.
Pilot
The pilot was Alaska State Representative Gary Knopp. He held a commercial pilot certificate but had been denied a medical certificate in 2012 due to vision issues.
Systems & Failure Modes
ADS-B Out/In
The PA-12 was equipped with ADS-B Out and In, but the DHC-2 lacked the equipment, preventing automated traffic alerts between the two aircraft.
CTAF (Common Traffic Advisory Frequency)
The lack of a mandatory CTAF reporting area for the Soldotna vicinity meant pilots were not required to broadcast their positions, reducing situational awareness.
Interesting Facts
- 01The pilot of the PA-12, Gary Knopp, was a member of the Alaska House of Representatives.
- 02Knopp had been denied medical certification in 2012 due to vision problems including glaucoma.
- 03The PA-12 had the incorrect registration number (N1904T) painted on its exterior, leading to initial misidentification.
- 04The DHC-2 was manufactured in 1956 and the PA-12 in 1946.
- 05NTSB calculations showed the PA-12 pilot would have received an ATAS alert 26 seconds before impact if the DHC-2 had been equipped with compatible technology.
Safety Actions & Advisories
Safety Recommendation A-21-17
The NTSB recommended the FAA require ADS-B Out and In-supported traffic advisory systems with aural and visual alerts for all Part 135 operations.
Safety Recommendation A-22-4
The NTSB recommended requiring pilots to report their positions on designated CTAF frequencies when operating in those areas.
Safety Recommendation A-22-5
The NTSB recommended the FAA create additional dedicated CTAF areas in locations with a high risk for midair collisions.