Accident History
On 04 May 2009, a Cessna 150L (registration C-GJAE, serial number 150-72055) operated by Air Richelieu departed Montréal/Saint-Hubert Airport at approximately 1556 eastern daylight time for a training flight. The student pilot, who began training on 27 April 2009, had completed 3.0 hours of ground instruction, 1.6 hours in a simulator, and 1.8 hours of flying time prior to the flight. The lesson plan included straight and level flight, climbs, and descents, with an expected duration of 1.3 hours. Weather conditions were ideal for visual flight.
The instructor made two position reports: one en route at 1604 and another upon reaching the training area at 1622. Radar data showed the aircraft traveling east then north, likely due to crowding in the nearest training area. The last valid radar position at 1633 indicated an altitude of 1340 feet above sea level (asl) on a track of 341 degrees with a ground speed of 90 knots. The last coasting target was captured at 1634. The radar floor in the area was approximately 1000 feet asl; the GPS unit had been turned off prior to departure.
After 1634, the aircraft flew below the radar floor at low altitude—approximately 200 feet above ground level (agl) toward Saint-Louis, then northeast at less than 100 feet agl over the Yamaska River. Hundreds of geese took flight as the aircraft passed. While in level flight at treetop height over the river, the aircraft traveled about 2.4 km before colliding with an unmarked telephone cable spanning the river from west to east at approximately 60 feet asl. The engine sound appeared normal prior to impact. The aircraft struck the cable with a 30-degree bank angle, then hit the water in a nose-down attitude and sank quickly. The instructor, seated in the right seat, was fatally injured. The student pilot in the left seat evacuated the aircraft but drowned. The occurrence took place at approximately 1637.
Wreckage and Impact Information
The telephone cable consisted of a black protective sheathing lashed to a steel cable; it did not break on impact. The aircraft wreckage was transported to the TSB Laboratory for examination. The engine cowls and outer two thirds of the right wing leading edge were not recovered. The cable was unmarked because it was not considered a hazard to aviation—it was approximately 52 feet asl, at the height of the river banks, and not near an airport, aerodrome, or water aerodrome.
Cause and Contributing Factors
The Transportation Safety Board of Canada found that the aircraft was flown at low altitude, causing it to collide with an unmarked telephone cable suspended 60 feet above sea level over the Yamaska River. Flying below 500 feet agl was not required for the planned exercises; the reason for deviating from the lesson plan and company procedures is unknown.
Risk and Mitigation
Low flying poses additional risks. Unmarked cables are difficult to detect. The telephone poles on either side of the river were hidden by trees and brush. Although not required by regulation, Télébec (Bell Alliant) subsequently installed red and white markers on the telephone cable spanning the Yamaska River.