Description

On 31 January 1986, at night during an instrument approach, a Shorts SD3-60 operated by Aer Lingus Commuter experienced a loss of control attributed to airframe ice accretion. When fully established on the Instrument Landing System (ILS), the aircraft began a series of divergent rolling oscillations which were accompanied by a very high rate of descent. The crew was able to regain control of the aircraft just before contact with power cables and subsequent impact with terrain near East Midlands Airport.

Synopsis

This is an extract from the Report (SL 2009/02) on the accident published by the Air Accident Investigation Branch (AAIB) UK:

During the descent and before entering the cloud tops at about FL60, the crew switched on the aircraft’s anti-ice system, which heats the windscreen, engine air intakes, propellers, static air vents and pitot probes, but in accordance with normal operating procedure, they did not use the wing and tail de-icing system. At this time the freezing level (0°C isotherm) was at 1000 feet, the temperature at FL60 was minus 6°C and the air was saturated. Whilst in cloud, which according to the non-handling pilot was particularly dense, ice thrown from the propellers was heard striking the side of the aircraft fuselage, and it was suggested that the propeller rpm be increased to expedite the removal of the ice. Both pilots state that, at some time during the descent, they visually checked the aircraft for ice but saw none. Nevertheless, several other flights during that evening have since reported the occurrence of severe icing.