What happened
During a night flight near Montreal, Quebec, a Cessna 172, registration C-GXSD, experienced a total loss of electrical power while operating in Class E airspace. The pilot, noticing a continuous discharge on the ammeter, attempted to navigate toward St-Hubert Airport. As the electrical failure progressed, the aircraft's radios ceased functioning and the transponder stopped transmitting, leaving the aircraft visible on radar only in primary mode.
Upon entering the St-Hubert Class D control zone, the pilot did not establish two-way communication and failed to follow the established arrival procedures for aircraft with no radio (NORDO). The pilot proceeded to land on runway 24L, which was the opposite direction of the active runway. Simultaneously, a Katana, registration C-GADA, was cleared for takeoff on runway 06R for a training flight. As the Katana began its takeoff roll, the instructor observed the dark, unlit Cessna 172 rolling in the opposite direction on the same runway. An attempt to clear the aircraft by flying over it resulted in the Katana's landing gear striking the roof of the Cessna. The collision caused extensive damage to both aircraft, and the three occupants involved sustained minor injuries.
The investigation
Investigators examined the wreckage of the Cessuna 172 and discovered that the alternator's positive-terminal cable was severely degraded. Only 7 of the 133 strands in the cable were still functional. The investigation determined that the cable had been installed with a bending radius smaller than the recommended standard, leading to fatigue loads and gradual wire breakage.
The investigation also reviewed the actions of air traffic controllers. While the terminal controller attempted to contact the aircraft multiple times, the investigation noted that the controller did not alert the St-Hubert tower to the potential communication failure. Furthermore, the pilot's lack of familiarity with the aircraft's electrical system and the specific NORDO arrival procedures at St-Hubert contributed to the difficulty in detecting the approaching aircraft in the dark.