Looking Back: Flying Into a Mountain Trap
On August13,1984, a float-equipped Cessna185D with four persons on board was being flown on a cross country flight from Nelson,B.C., to Vernon,B.C. The Cessna failed to arrive at destination. An airliner picked up an emergency locator transmitter (ELT) signal; the subsequent search located the wreckage in a valley at 5200ft above sea level (ASL), approximately 10 NM northwest of Edgewood, B.C.
The aircraft had struck the ground on a southeasterly heading in a steep nose-down attitude. On impact with the tree-covered terrain, both wings collapsed forward, and the fuselage folded over the engine at the firewall. All four occupants were killed.
Common yet extremely insidious and dangerous situation
for pilots flying in mountainous regions
Through a distance of about 10 mi., the terrain rises from 1 446ft ASL-at the entrance to the valley-to 5200ft ASL-at the accident site. The terrain north and west of the accident site is higher still, rising to 7412 ft ASL. The aircraft’s route was up the valley, in a northwest direction, toward the rising terrain. At the time of the accident, the wind was from the southwest at 14kt; the sky was clear; the visibility was in excess of 15 mi.; the temperature was 22°C.
The owner of the aircraft was in the right seat, and a less experienced pilot was occupying the left seat. It could not be determined who had been flying at the time of the accident. No flight plan had been filed, and there were no witnesses to the accident. The aircraft engine was operating at 2 100 rpm on impact, and appeared to be serviceable. The flight path into the trees and the damage sustained by the aircraft were both indicative of an aircraft in a spin.
In its report, the Transportation Safety Board of Canada (TSB) suggested that the pilot likely attempted to reverse course when he realized that the aircraft would not clear the terrain ahead, and, during this turn, the aircraft stalled and entered a spin. The TSB issued a single finding:the aircraft departed from controlled flight for undetermined reasons while navigating through a mountain valley with rising terrain ahead.
From TSB File84-P40044
Source: Transport Canada Website