What happened
On 03 April 2001, a Royal Cargo Boeing 737-20 and two crew members were conducting a scheduled cargo flight from Halifax to St. John's, Newfoundland. Prior to departure from Halifax, the pilot flying did not review the most recent notices to airmen. Upon arrival in the St. John's area, the crew faced challenging weather conditions, including light snow, blowing snow, and low visibility. Due to the unserviceability of the instrument landing system on Runway 11, the crew decided to attempt an ILS approach to Runway 16.
During the descent, the crew received conflicting wind information. While the Halifax Flight Service Station had reported high winds, the Gander Area Control Centre provided a much lower wind estimate. This discrepancy was caused by an iced-over anemometer at the airport, which provided inaccurate data to air traffic control. Additionally, the crew did not properly acknowledge a significant meteorological report warning of severe mechanical turbulence.
As the aircraft approached the runway, the crew calculated an approach speed based on the incorrect, lower wind data and applied a gust correction factor. During the final approach, the aircraft encountered turbulence that caused fluctuations in airspeed and uncommanded pitch and roll deviations. The aircraft touched down at 164 KIAS, which was 27 knots faster than the intended touchdown speed. The aircraft traveled approximately 2500 feet beyond the runway threshold and exited the departure end of the runway into deep snow, coming to rest 75 feet beyond the centerline.
Findings
- The crew utilized incorrect wind information provided by Gander ACC, which was the result of an unserviceable, iced anemometer.
- The approach speed was calculated using erroneous data and an incorrect application of gust increments.
- The crew failed to properly acknowledge a SIGMET warning regarding severe mechanical turbulence.
- The aircraft touched down at a speed significantly higher than the target Vref.