What happened
On a night in February, an Air Canada Canadair Regional Jet (CL-65) was performing a straight-in instrument landing at Fredericton, New Brunswick. The aircraft, operating as flight 6/646, landed on runway 15 during conditions involving light snow and a 10-knot crosswind. The runway surface was reported as containing light slush and snow.
During the after-landing roll, as the aircraft's speed decreased through 40 knots, the plane began to yaw to the left. In an attempt to regain directional control, the pilot flying reduced reverse thrust and stowed the reversers. However, the reversers were moved to the stowed position before the engines had fully transitioned to idle reverse. This caused the engines to produce forward thrust, which arrested the aircraft's deceleration. The aircraft continued to veer left, eventually exiting the runway approximately 5,500 feet beyond the threshold. The nose gear subsequently sank into the soft ground adjacent to the runway. There were no injuries to the crew or passengers, and the aircraft sustained no damage.
The investigation
Investigators examined flight data from the FDR and CVR, as well as maintenance records and weather reports. The investigation established that the aircraft's weight and center of gravity were within limits and no mechanical deficiencies were found.
Analysis of the flight data showed that the crew maintained high reverse thrust levels (84% N1) until 35 knots, which exceeded the manufacturer's recommendation to reduce thrust below 30% N1 at speeds under 60 knots to avoid foreign object damage. Furthermore, the investigation found that the pilot maintained heavy braking during the yaw, which minimized the tire cornering forces available to steer the aircraft. The rudder was also found to be ineffective due to the low airspeed at the time of the excursion.
Findings
- The flight crew was unable to maintain directional control of the aircraft during the landing roll.
- The loss of control was initiated by the combination of a left crosswind and a slippery runway surface.
- The engines had not spooled down to idle before the reversers were stowed, resulting in an unintended transition to forward thrust.
- The pilot's decision to maintain braking during the veer reduced the lateral forces available to counteract the leftward movement.