A Dassault-Breguet Falcon 20D, configured as a cargo aircraft, operated a flight with a crew of two on this day in aviation history, December 30, 1998. The flight departed Gander (CYQX, Canada) at 14:45 lt (local time) and progressed without any issues towards its destination, St John's (CYYT, Canada)
While en route, the crew received information that the Glideslope for the ILS of Runway 16 at St. John's was unserviceable, as was the airport's wind speed indicator. The crew received a weather forecast (TAF) for their destination which read;
Winds - 110/25 gusting 35 knots
Visibility - 0,5 miles
Light freezing rain and fog
Vertical visibility 200 feet
Clouds - 1000 feet overcast
As the ILS was not available a Localizer approach for runway 16 was briefed, although the ceiling was reported below landing minima for such an approach. The crew decided to attempt a Localizer approach after receiving a PIREP (Pilot Report) from a preceding aircraft, which did not contain any comment on turbulence.
20 Nautical Miles from the runway the crew received the approach clearance, during the initial approach some light turbulence was encountered. At 3000 feet ASL the Captain, as the pilot flying, reduced the descent rate and the speed. Turbulence started to increase, resulting in a rapid increase in airspeed and drift. This did not concern the crew as they had encountered these conditions on prior flights into St. John's. After configuring the aircraft for landing the aircraft encountered severe turbulence, resulting in an uncontrollable and rapid loss of altitude.
The pilot monitoring observed the terrain outside and called out "TERRAIN". This was immediately followed by the initiation of a wind shear recovery by applying maximum power and increasing the pitch attitude until the stall warning was heard. This was not enough to prevent the aircraft from descending on the trees, after clipping some trees the aircraft began to climb, the crew discontinued the approach, and an emergency was declared. While being vectored for a second approach the Glideslope for runway 16 became available and an uneventfull ILS approach and landing followed.
Damage to the aircraft was extensive and was concentrated on the left wing
Outboard three feet of the droop leading edge was torn loose and folded under the wing
The lower skin of the outboard wing extension was twisted
Impact damage on the inboard droop and fixed leading edges
Minor damage to the aileron and outboard flap
Ground damage was limited to a number of black spruce trees in an unpopulated area. The six- to seven-foot tall trees had been broken off three to four feet above the ground.
The crew was not injured during the incident.
Extensive repairs were completed, and the aircraft was returned to service, in the spring of 2010 the aircraft was withdrawn from service and stored at Denton Municipal, TX, USA.
The aircraft as seen in 2010, stored (source; Aerial Visuals © John Bennett)
An investigation was launched by the Transportation Safety Board of Canada (TSB). In their Aviation Investigation Report, they listed the following Findings as to Causes and Contributing Factors;
The weather conditions on the approach to St. John's Airport were conducive to severe turbulence, wind shear, and downdrafts.
The aircraft encountered severe turbulence and downdrafts which caused a sudden loss of altitude and subsequent impact with the trees.
The pilot applied the correct wind shear recovery techniques.
Other findings included the removal of warnings for downdrafts on the approach charts. For a full list of other findings, please click on the .pdf file below. This file contains the complete Aviation Investigation Report as published by the TSB, and served as the source for this blog;