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Report: Canadair RJ uncommanded roll on takeoff in icing conditions
15 April 2011

The CRJ shortly before Stick pusher activates (graphic from AIBN animation)

AIBN Norway published the final report of their investigation into an serious incident involving a Cimber Air Denmark Canadair CRJ200LR Regional Jet, January 2008. During take-off, immediately after lift-off, the aircraft suddenly lost lift on the right wing. The wing dropped, sending the aircraft into an uncontrolled 40-degree bank. The stall protection system activated, and the crew regained control 

On 31 January 2008, at 17:21 hours, a serious aircraft incident took place during take-off from runway 19L at Oslo Airport Gardermoen (ENGM). A Canadair CRJ200LR aircraft with two pilots and two cabin crew members on board suddenly lost lift on the right wing, causing the wing to drop and sending the aircraft into an uncontrolled 40-degree bank immediately after lift-off. The stall protection system activated, and the crew regained control and continued as scheduled to Copenhagen.
The investigation has shown that prescribed de-icing took place 15 minutes prior to departure, and that the wings were not cold-soaked in advance. Weather conditions were temperature at freezing, 15 kt wind and continuous precipitation in the form of aggregated, wet snowflakes. The runway was covered by slush and wet snow which had fallen after the runway had been cleared of snow and sanded 30 minutes earlier. Unintentionally, due to distraction, the system for heating the leading edge of the wing was not switched on prior to take-off. The nose wheel was lifted from the ground at the correct speed, but at a higher than recommended rotation rate.
This incident is one in a number of similar cases. From 2002 to 2008, six CL-600 series aircraft were involved in accidents during winter conditions. The wing of the aircraft type has proven to be especially sensitive to contamination on the leading edge. After the accidents, a number of measures have been implemented to ensure that the wing is clean during take-off, and to ensure that the pilots use the correct take-off technique.

The AIBN believes that the safety measures that have been introduced have not resulted in a definitive solution to the problem. When the de-icing fluid runs off during take-off, it is essential that the leading edge of the wing is heated. On take-off from contaminated runways, spray from the nose wheel will envelop the aircraft’s wing root. This source of contamination hits an aerodynamically critical area on the wing, and comes in addition to the precipitation which can adhere to the wing and disturb the airflow. The AIBN believes that it is not sufficient to depend solely on ”soft” safety barriers such as check lists and memory when the position of one switch (Wing Anti-Ice ON) can be critical to prevent a catastrophic accident during take-off. Technical or physical safety barriers in the form of design changes, automatic systems or automatic warning systems are, in the opinion of the Accident Investigation Board, necessary to obtain adequate reduction in accident risk. Alternatively, more severe restrictions for winter operations with the affected aircraft models must be introduced.

The Accident Investigation Board issues four safety recommendations.

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