Douglas DC-3C C-GWUG, was usually used on cargo flights between Vancouver and Nanaimo. Because of delayed arrival of a Purolator Boeing 727, the route of C-GWUG was changed to Vancouver-Victoria-Nanaimo, operating for Purolator Courier. Vancouver tower cleared the aircraft for takeoff at 06:22 PST from runway 26L. After takeoff, the aircraft turned left on a track toward Active Pass. During the departure climb, the captain requested an altitude of 1000 feet above sea level; the tower controller approved this request. The aircraft left the Vancouver control zone at 06:26 and entered Class E (controlled) airspace. As the aircraft approached the Gulf Islands, it descended slightly and remained level at 900 feet asl. It crossed about 0.25 nm west of the Active Pass NDB at 06:32 while remaining steady at 130 knots (ground speed) and level at 900 feet asl. At 0633:04, the aircraft descended to 800 feet asl for about nine seconds. The last radar data show the aircraft at 900 feet asl and 130 knots. At this altitude he aircraft initially struck trees on the ridge of Mount Parke and cut a swath through the treetops of about 200 feet long and 70 feet wide. After passing through the trees on the ridge top, the aircraft continued over a cliff in the direction of flight for approximately 1100 feet while dropping about 600 feet to the valley floor. CONCLUSIONS: Findings as to Causes and Contributing Factors: – The accident flight was not conducted in accordance with the night obstacle clearance requirements of Canadian Aviation Regulation (CAR) 705.32. – The Kelowna Flightcraft company operations manual did not reflect the restrictive conditions imposed on night visual flight rules (VFR) flight by CAR 705.32. Such information might have prevented the accident by ensuring the crew’s awareness of those night obstacle clearance standards. – As the aircraft approached Mayne Island, it encountered a low cloud ceiling that was based about 800 feet and that reduced visual reference with the surface. – When the aircraft struck trees, it was being flown in controlled, level flight at an altitude below the surrounding terrain. – The aircraft was not equipped with a ground proximity warning system or any other similar system that could warn the crew of an impending collision with terrain. Such systems were not required by regulation. Findings as to Risk – Kelowna Flightcraft flight operations personnel were not aware that most of the DC-3 flights were being conducted under VFR. – First responders were not aware of the presence of the dangerous goods and were therefore at increased risk during their response activities on the site. Other Findings – Transport Canada officials responsible for monitoring this operation were not aware that most of the DC-3 flights were being conducted under VFR at night and below the required obstacle clearance altitudes.