Accident Overview
On a daytime visual flight rules (VFR) flight from Okanagan Lake near Kelowna to Pitt Meadows, British Columbia, a privately operated de Havilland DHC-2 MK 1 amphibious floatplane (registration C-GCZA, serial number 1667) with a pilot and two passengers on board struck trees and collided with terrain. The collision occurred close to and 100 feet below the level of Highway 97C, near the Brenda Mines tailings hill. At 1850 Pacific Daylight Time, a brief 406-megahertz emergency-locator-transmitter (ELT) signal was detected, which identified the aircraft, but a precise location could not be determined. Most of the aircraft was consumed by a post-impact fire. The three occupants were fatally injured.
Investigation Findings
The investigation found no indication that an aircraft system malfunction contributed to the occurrence. There were no drastic changes in the aircraft’s flight path, and no emergency calls from the pilot to indicate an in-flight emergency. The constant ground speed and flight path suggested that the aircraft was under the control of the pilot. The analysis therefore focused on controlled flight into terrain (CFIT).
Cause and Contributing Factors
Two contributing factors were identified: 1. The combination of relatively high weight, effects of density altitude, and down-flowing air likely reduced the climb performance of the aircraft, resulting in its altitude being lower than anticipated at that stage in the flight. 2. The pilot’s vision was likely impaired by the sun, and the pilot may have been exposed to visual illusions; both were factors that contributed to the pilot not noticing the trees and rising terrain, and colliding with them.
Risk Findings
Two risk-related findings were noted: 1. Visual illusions cause false impressions or misconceptions of actual conditions. Unrecognized and uncorrected spatial disorientation caused by illusions carries a high risk of incident or accident. 2. When there are no special departure procedures published for airports in mountainous regions surrounded by high terrain, there is a risk of pilots departing the valley at an altitude too low for terrain clearance.
Other Findings
Information from the Wide Area Multilateration system was not preserved following the occurrence, as local NAV CANADA personnel were not aware that unfiltered data were only available for a limited time.