Pilots of an Air Greenland de Havilland Canada Dash 8-200 carried out an unstable steep approach to Ilulissat in above-limit crosswinds, before the resulting hard landing caused a main-gear collapse.
The aircraft was destroyed as it skidded off runway 07 and down a snow-covered slope, but only minor injuries were sustained among the 15 occupants.
Danish investigation authority HCL found that the crew had agreed to a visual steep approach of 5.1° and a reference airspeed of 99kt.
They also agreed a crosswind limitation of 31kt, above the operator’s limit of 25kt. The wind conditions given to the crew during short final approach warned of speeds up to 39kt.
Under these circumstances, says the inquiry, “a landing was prohibited”.
HCL says the captain chose to reduce the time spent on final approach by flying the turboprop “on the high side” of the steep glideslope.
But the wind conditions, and the low flap setting of 15°, affected the crew’s ability to handle the aircraft. The inquiry says this “made it difficult” to maintain stabilised approach criteria.
As it passed below 1,000ft the Dash 8’s airspeed was still 144kt, exceeding the operator’s stable-approach maximum of 119kt for the aircraft’s configuration. The airspeed was still 138kt shortly after descending below 500ft.
The crew retarded the throttle levers to the flight-idle setting at 200ft, causing the aircraft to descend more rapidly – in excess of 1,000ft/min – and sink beneath the 5.1° glideslope. This descent rate increased to 1,100ft/min at 50ft, with the airspeed still at 128kt.
HCL says the final approach to the runway “was not stabilised” but poor crew resource management led to “target fixation” by the pilots and a “mental blocking” of any decision to execute a go-around.
While still airborne, below a height of 20ft, the crew retarded the throttle below the flight-idle setting – into the ‘beta range’ normally used on the ground.
Use of this setting in flight presents significant risks of propeller overspeed and engine damage. But a warning horn to alert the crew does not activate if the aircraft is below 20ft.
“At that point, no safety barriers were left,” says the inquiry.
With a 6.6° left bank, the Dash 8 touched down hard on its left main landing-gear with an impact of 2.4g. The force of the landing overloaded the structure and the gear collapsed.
As the aircraft skidded, the crew cycled the throttle levers between the ground and flight setting, preventing the turboprop from decelerating and prolonging the landing roll. The use of full left rudder and “no decisive use” of reverse thrust on the right-hand side, says HCL, made subsequent directional control “impossible”.
Source: Cirium Dashboard
