29th of January 2014, Blog #584
After a diversion to Kangerlussuaq Airport (Greenland) the previous night, the crew of a Bombardier DHC-8-202 (Dash-8) was preparing the aircraft for a domestic flight to Ilulissat Airport (Greenland). on this day in aviation history in 2014. Onboard the aircraft for the flight, a crew of three and 12 passengers. The diversion, the night before, was caused by adverse weather at Ilulissat Airport.
The aircraft in its final position, note the skid/tire marks on the snowbank behind the tail (© AIBD)
During the flight preparation, the commander contacted Ilulissat several times to obtain weather information. The wind was reported to be from 130º (magnetic) at 20 knots, with a maximum of 40 knots. The braking coefficient values were reported to be 85, 84, and 83. No issues were found during the physical inspection of the aircraft during the preflight inspection, and at 11.06 UTC the aircraft departed Kangerlussuaq with the commander as the pilot flying and the first officer as the pilot monitoring
During the flight to Ilulissat to crew obtained a special weather report, the report issued at 11:09 UTC gave the following weather;
Wind 100º at 20 knots, maximum 30 knots
Visibility 10 kilometres
Clouds broken 12.000 feet
QNH 984 hPa
Based on the weather a visual approach to runway 07 at Ilulissat, a steep approach with an approach path of 5.1º was selected with an NDB/DME approach to runway 07 as a backup. A visual missed approach procedure was also briefed. The crosswind limit was determined to be 31 knots (including gusts). At 11:33 UTC the crew contacted the Ilulissat AFO, reporting 28 nm out and passing 12.000 feet while descending. The following information was received at the time by the crew;
The runway in use was 07
The wind conditions were 150° magnetic 24 knots - maximum 33 knots - minimum 17 knots (The crosswind was 24 knots - The headwind was 5 knots)
The wind at threshold runway 25 was gusting to 41 knots
The visibility was 10 kilometres
Broken clouds were at 12 000 feet -
The temperature was +3° Celsius
The dewpoint was -9° Celsius
The QNH was 983 hPa
Close-up of the damaged aircraft (© AIBD)
Due to the (cross) wind conditions, a flap 15º landing was decided upon by the crew, and the landing reference speed (Vref) was set to 99 knots.
While on a five-mile final from runway 07, the wind conditions were reported to be 140° magnetic and 28 knots - maximum 35 knots and the crosswinds 26 knots. At this time the autopilot was disengaged. At 1000 feet Radio Altitude the landing checklist was completed, and no callouts were made that the approach was stabilised, while the aircraft flew through moderate turbulence. At a height of 20 feet, the power levers were pulled back below flight idle into the ground beta range (reverse pitch on propellor). this caused a hard touchdown on the left main landing gear, which failed under a +2.4 G loading. After the gear collapsed the power levers were cycled back and forward a number of times, and the crew perceived that the aircraft did not decelerate. ~382 meters after touchdown, the aircraft skidded to the left, left the runway, and entered the runway safety area; the speed at this point was 68 knots.
The aircraft in its final position, down the embankment (© AIBD) The aircraft continued in an increasingly sideways skid in a nose-right position. Shortly before, the aircraft skidded off the left side of the safety zone and in order to reduce the risk of a potential fire, the first officer selected both condition levers to fuel off. The first officer did not coordinate this action with the commander. The aircraft departed the safety zone at an airspeed of 40 knots CAS, and on a heading of 068º magnetic. The aircraft hit one of the PAPI lights for runway 25, skidded down a steep snow-covered slope and impacted a rocky area approximately 10 meters below the runway elevation, where it came to a stop. The aircraft was shut down and an evacuation was completed in less than 40 seconds, 1 crew member and 1 passenger received minor engines.
The final approach and landing animation, based on the SSFDR data (© AIBD)
The Havrikommissionen (Accident Investigation Board Denmark - AIBD) investigated the accident. In their report (which served as the source for this blog) they identified 45 findings and five factors in relation to this accident. Summarised these five factors were;
Non-optimum CRM during the final approach
The left main landing gear fuse failed under overload conditions
Cycling of the left power levers prevented adequate deceleration
The crew was unable to maintain directional control
All details on the findings and factors of this accident can be found in the accident report from the AIBD, which can be accessed by clicking on the .pdf file below;