TCAL Flight 831 from Montreal (YUL) to Toronto (YYZ) was cleared for Toronto at FL290 and was instructed to report climbing through 3000 and 7000 feet. The DC-8 started the takeoff roll on runway 06 at 18:28. Last radio contact with the fight was when the crew reported climbing through 3000 feet, acknowledging a clearance for a left turn to St. Eustache. The aircraft then deviated from its normal flight path about 55deg to the right and began a quick descent. At 18:33, 16.9mls from the airport, the DC-8 struck the ground at a speed of 470-485 knots descending in an angle of about 55deg (+/- 7deg). It was found that the pitch trim compensator actuator was in the extended position and the horizontal stabilizer at setting of 1.9deg nose down on the right hand side and between 1.6deg and 1.7deg nose down on the left hand side.
PROBABLE CAUSE: "The probable cause of this accident could not be determined with certainty. Certain possible causes which were put forward could not be ruled out: 1) Icing of the Pitot system; 2) Failure of the vertical gyro; 3) An unprogrammed and unnoticed extension of the Pitch Trim Compensator."
Aviation Safety Report
Wikipedia
photo Ken Fielding
