What happened
On February 24, 2004, at 0544 MST, a Boeing 737-210C, registration C-GNWN, was completing a charter flight from Lupin, Nunavut, to Edmonton, Alberta. During the instrument landing system approach to Runway 12, the aircraft encountered heavy fog. While the crew had been provided a runway visual range of 1200 RVR, the visibility deteriorated significantly during the approach.
As the aircraft descended, the captain took manual control at approximately 65 feet above the ground. During the flare, the aircraft drifted left of the centerline, resulting in a hard touchdown with a vertical deceleration of 2.3g. The aircraft landed approximately 8 feet off the left edge of the runway and traveled 1600 feet before returning to the runway surface. During the excursion, the aircraft struck one runway light, four taxiway lights, and one hold sign. There were no injuries to the passengers or crew.
The investigation
The investigation examined the aircraft's flight data, cockpit voice recordings, and the flight crew's recent duty history. Technical analysis of the Boeing 737-210C showed that all systems, including the engines and avionics, were functioning according to design specifications. The investigation also reviewed the aerodrome weather reports, which indicated visibility had dropped to 1/8 statute mile in freezing fog shortly after the incident.
Investigators also looked into the crew's fatigue levels, noting they had been awake for nearly 24 hours prior to the landing. Furthermore, the investigation reviewed the company's standard operating procedures (SOPs) and the use of the VOR/LOC autopilot mode during the approach.
Findings
- The captain was unable to maintain the aircraft within the runway boundaries because deteriorating visibility and the lack of adequate runway lighting prevented sufficient visual guidance.
- The approach was performed using VOR/LOC mode rather than AUTO/APP mode, which prevented the autopilot from using its built-in desensitizing features to stabilize the aircraft near the ground.
- The flight crew's performance may have been impacted by extended periods of wakefulness, as current regulations and company policies did not sufficiently address the need for restorative sleep or the management of circadian rhythm shifts.
- Canadian regulations allowed for Category I approaches in weather conditions that lacked the robust lighting requirements found in Category II operations.