The aircraft, with a crew of three and five civilian spotters, was engaged in an Air Search Mission in the Kananaskis area west of Calgary, after two airplanes were missing. The weather was good and the terrain consisted of hills and valleys with peaks up to 7,000 feet. The search profile was a 500 feet AGL contour search. Two hours and 20 minutes after takeoff, the aircraft impacted at 5,900 feet ASL on the west slope of 6,200 foot feature. The aircraft was destroyed by impact and post crash fire, and all occupants sustained fatal injuries. Crew: Cpt D. Wayne Plumbtree, pilot, Cpt E. M. Kates, copilot, Sgt Brian G. Burkitt, flight engineer. Passengers: Mr. D. Hall, Mr. J. Schindler, Mr. C. Masur, Mr. C. Grant, Miss P. McLean.
Probable cause (official findings): The following causal factors were identified: Personnel - Pilot - Visual illusion - The pilot at the controls of the aircraft carried out an overhead recce of the valley. The lighting conditions, absence of shadows and lack of contrast in the valley was such that the rock outcrop was masked by the surrounding rockface. The valley, in the absence of this rock outcrop, was large enough to permit the flight operation to be conducted. Personnel - Pilot - Expectancy - The low contrast terrain created the visual illusion experienced during the initial contour at approximately 7,000 feet ASL so that the pilot did not expect to see the rock outcrop during the final flight path at 6,100 feet ASL. Therefore, the pilot was slow to recognize and react to the environmental cues which indicated the hazards of the valley. Personnel - Pilot - Pressing - The crew of the aircraft were attempting to complete 500 and 1/2 search coverage of their area. To obtain this coverage, the crew believed they had to fly into the valley in order to complete their mission. Personnel - Supervision - 418 Squadron - Squadron supervisory staff did not ensure that current, qualified aircrew were assigned to this mission and that the mission was properly authorized. The following findings have been determined: - Neither pilot was current in accordance with CFACM 60-2604. - The search mission was not authorized in accordance with 418 Squadron Flying Orders.