What happened
On a scheduled flight from Calgary to Ottawa, a WestJet Boeing 737-700, registration C-GLWS, experienced a runway excursion at MacDonald Cartier International Airport. The flight, carrying 86 passengers and 6 crew members, was originally prepared for an approach to Runway 14. However, due to a misinterpretation of the ceiling height by air traffic control, the approach was changed to Runway 07.
During the approach, the crew encountered a significant tailwind component of 74 knots. This wind caused difficulty with energy management, leading to an unstable approach where the aircraft was above the glide path and maintaining a high rate of descent. Despite the crew's efforts to reduce airspeed by deploying speed brakes and leveling off, the aircraft touched down approximately 2300 feet past the threshold at 140 knots.
Upon touchdown, the aircraft was unable to stop within the remaining runway length. The aircraft exited the end of Runway 07 at 40 knots, traveling approximately 215 feet into a snow-covered area. There were no injuries to the passengers or crew, and the aircraft sustained no damage.
The investigation
The TSB examined the aircraft's flight data, maintenance records, and the environmental conditions at the time of the event. The investigation looked into the crew's performance, specifically regarding the stabilized approach criteria and the impact of task saturation. The investigation also reviewed air traffic control (ATC) procedures, including the accuracy of the ATIS broadcasts and the reporting of braking action.
Investigators found that the aircraft had one inoperative thrust reverser, which was permitted under the Minimum Equipment List (MEL). The investigation also noted that the speed brakes were not re-armed for landing after being stowed during the approach, which marginally increased the required stopping distance.
Findings
- The crew struggled with energy management due to the strong tailwind, which prevented a stabilized approach.
- The captain experienced task saturation while coaching the first officer, which led to a failure to assess the unstabilized approach and a failure to acknowledge braking action reports.
- The runway surface was more slippery than reported, which, when combined with the high touchdown speed and long landing roll, caused the overrun.
- ATC braking action reports lacked the aircraft type and time, reducing their utility for the crew.
- A misinterpretation of weather data by ATC led to the runway change, which introduced the problematic tailwind.