What happened
On a summer afternoon in British Columbia, a de Havilland DHC-2 Mk. 1 Beaver, registration C-GHAF, departed Penticton Airport for a flight toward Calgary, Alberta. The aircraft was carrying the pilot and two passengers, with the belly tanks fully loaded with 184 litres of fuel and the cabin containing various cargo and luggage. After navigating around airspace restrictions caused by local forest fires, the aircraft departed Penticton at 1420 PDT.
Approximately seven minutes into the flight, the aircraft struck treetops in a steep ravine within Penticton Creek, roughly 11 nautical miles northeast of the airport. The impact caused the aircraft to crash in a descending attitude, triggering a post-impact fire that consumed much of the fuselage and ignited a small forest fire. All three occupants were fatally injured.
The investigation
The investigation examined the aircraft's weight, performance, and the pilot's flight path. While the aircraft was equipped with Wipline 6100A floats, investigators found that the necessary structural modifications required to operate at a maximum takeoff weight of 5370 pounds had not been completed. Consequently, the legal maximum takeoff weight was actually 5100 pounds.
Post-accident analysis revealed the aircraft weighed at least 5350 pounds, exceeding its legal limit by at least 250 pounds. This overweight condition, combined with the effects of density altitude, significantly degraded the aircraft's climb performance. Additionally, investigators looked into the medical history of a passenger who had a known history of coronary artery disease that had not been disclosed during her last medical examination.
Findings
- The pilot approached rising terrain head-on and failed to execute a turn to avoid the obstacle.
- The aircraft's ability to clear the terrain was compromised by the combination of high density altitude and an excessive takeoff weight.
- The aircraft was operating beyond its certified weight limits because required structural modifications for the higher weight threshold were missing.
- A passenger's undisclosed medical condition presented a potential risk to flight safety.