Description

On 14 September 2005, an ATR 42-320 operated by Coast Air AS experienced a continuous build up of ice in the climb, despite the activation of de-icing systems aircraft entered an uncontrolled roll and lost 1500ft in altitude. The crew initiated recovery actions, the aircraft was stabilised, and the flight continued without further event.

Synopsis

This is an extract from the Report (SL 2009/02) to serious incident published by the Accident Investigation Board Norway (AIBN):

A cold front had passed over the coast and was on its way east, and local moderate icing was forecast […]. There was a relatively strong westerly wind, and the crew anticipated some turbulence during the climb. The weather forecast was a moderate risk of local icing in western part of Norway up to flight level FL180 (approx. 18,000 ft), which is normal for the time of year.

After take-off and during climb with an engaged autopilot: