With two crew onboard, a Falcon 20D was operating a cargo flight from Gander to St John's (both in Newfoundland Canada) on the 3oth of December 1998. During their flight preparations, the crew recorded the following Aerodrome forecast;
Surface winds 110 degrees true at 25 knots gusting to 35 knots, visibility 0.5 statute mile (sm) in light freezing rain and fog, vertical visibility 200 feet, temporarily 3 sm in light freezing rain, light snow pellets and light freezing drizzle, 1000 feet overcast.
They were also informed that the Instrument Landing System (ILS) for runway 16 and the anemometer (wind speed indicator) at St John's were unserviceable.
The left outer wing (Source & © TSB) After an uneventful flight, the aircraft was cleared for the localizer approach to runway 16. Although the ceiling was below the landing minima for the approach, the crew decided to attempt the approach after receiving a pilot report from an aircraft landing ahead of them on Runway 16. There was no report of turbulence and the wind was estimated to be 150º at 10 knots, gusting at 25 knots. During the initial descent, some light turbulence was encountered., at ~3000 feet, the captain (pilot flying - PF) reduced the descent rate and speed. At the same time, the turbulence started to increase, followed a short while later by an increase in airspeed and drift, These conditions were a familiar occurrence to the crew, which had operated several times into St. John's recently, encountering similar conditions. As the crew configured the aircraft for landing and turned toward the localizer the turbulence significantly increased to severe. This was followed by an uncontrollable and very rapid loss of altitude. The captain immediately initiated corrective action by increasing the thrust to maximum and increasing the pitch attitude, until the stall warning was heard. As the aircraft descended into some trees it began to climb and the approach was aborted. The crew contacted ATC, declaring an emergency. While they were being vectored for a second approach the glide slope became available and an uneventful ILS approach was flow, followed by a normal landing.
St John's Airport New Foundland, Canada (Source; Public Domain) The crew did not sustain any injuries. The aircraft did sustain some serious damage;
Approximately three feet of the outboard droop leading edge was torn loose and curled under the wing;
The outboard wing extension lower skin was twisted;
The aileron and outboard flap panel exhibited minor damage.
The left-wing inboard droop and fixed leading edges exhibited several substantial impact marks.
Evidence of how close this aircraft came to the ground was apparent when the trees the aircraft hit were inspected. The six- to seven-foot tall trees had been broken off three to four feet above the ground. The incident was alerted to the Transportation Safety Board of Canada which published an extensive report into the incident on the 7th of June 2000. This report includes extensive information on the weather conditions encountered by the aircraft. (the report is available in .pdf format at the end of this blog).
The incident aircraft in Jul 1989, being used by an different operator (©Paul Denton)
The TSB concluded their report with the following findings as to causes and contributing factors;
The weather conditions on the approach at 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.