What happened
A DC-8 was conducting a conversion training mission from Montreal to Ottawa with three crew members on board. The flight initially operated under an instrument flight plan, which was canceled once the aircraft reached the Ottawa vicinity. During the flight, the crew performed a simulation of a hydraulic failure and completed a touch-and-go landing on runway 32.
During the subsequent maneuvers, the crew engaged in various engine power adjustments and flight control mode changes. Specifically, the rudder was switched to manual mode, and the engines were manipulated to simulate asymmetric flight conditions. As the aircraft transitioned to its final approach, the pilot-in-scale indicated uncertainty regarding whether a full stop landing would be attempted, before later confirming the intention to land.
During the descent, several power changes occurred across the four engines. Approximately 109 seconds before impact, the aircraft began a turn toward the runway heading. While the rate of descent remained relatively steady at roughly 700 feet per minute, the airspeed decreased. As the aircraft approached the ground, power was significantly increased on the number 1 and 2 engines. This surge in power occurred only 8 seconds before impact, when the aircraft was approximately 200 feet above the terrain. At this stage, the crew could no longer maintain a left wing-down attitude, leading to a rapid rightward roll and yaw. The DC-8 struck the ground in an inverted, nose-low position, roughly 1,995 feet short of the runway 32 threshold. The accident resulted in three fatalities.
Findings
The investigation concluded that the crew failed to abort a training maneuver when conditions no longer allowed for sufficient flight control. Key contributing factors included the improper decision to attempt an asymmetric approach while using manual rudder mode and the fact that increased power to the left engines was applied too late in the approach at an airspeed insufficient for effective control. Additionally, it was noted that a faulty check valve had closed during the flight, and the available technical manuals provided inadequate information regarding two-engine operating procedures.