What happened
On a cargo flight from Gander to St. John's, Newfoundland, a Falcon 20D operated by Knighthavok Air Express Limited encountered extreme weather during its instrument approach to runway 16. While the crew was aware of unserviceable glide slope and anemometer equipment at the airport, they proceeded based on a recent pilot report that indicated no turbulence.
As the aircraft descended, the crew experienced a rapid transition from light turbulence to severe conditions, including a sudden increase in airspeed and drift. This was followed by an uncontrollable loss of altitude. The pilot flying attempted a wind shear recovery by applying maximum power and adjusting pitch, but the aircraft struck the tops of trees at 1515 NST. The impact caused substantial damage to the left wing, including a torn leading edge and damaged flaps. There were no injuries to the two crew members on board. Following the incident, the crew declared an emergency and successfully completed a second approach once the glide slope became operational.
The investigation
The investigation focused on weather information, crew decision-making, and aerodrome procedures. Investigators found that the actual wind conditions were significantly stronger than the estimates provided to the crew. While the crew had flown into St. John's recently without issue, they were not prepared for the specific wind shear and severe downdrafts encountered during this approach.
Furthermore, the investigation examined the adequacy of aeronautical information. It was noted that the area forecast provided to the crew did not accurately reflect the turbulence levels, and the cautionary notes on the approach plates had been updated in a way that removed specific warnings about dangerous downdrafts. The investigation also looked into whether the obstacle clearance altitude for the intermediate approach was sufficient given the local terrain.
Findings
- The primary cause of the impact was the encounter with severe turbulence and downdrafts that triggered a rapid loss of altitude.
- The crew utilized appropriate wind shear recovery techniques.
- The aircraft was within weight and balance limits, and the crew was properly certified and trained.
- The weather conditions at the airport were highly conducive to the development of wind shear and turbulence.
- There was a lack of adequate warning regarding these specific hazards in the Canada Flight Supplement (CFS) and the approach plates.
- The current obstacle clearance altitude does not sufficiently account for the risks posed by the precipitous terrain in the area.