Incident Overview
A Shorts 360 aircraft, operating as Aer Lingus flight 328 from Dublin (DUB) to East Midlands Airport (EMA), experienced a sudden and severe loss of control during the final approach. The aircraft struck power cables and trees before coming to rest in a wood adjacent to a barley field. The cockpit and passenger cabin remained relatively undamaged, and no fire occurred. All passengers and crew successfully evacuated via the front and rear emergency exits.
Flight and Weather Conditions
The pre-flight briefing indicated that precision radar at East Midlands was unserviceable, but precision approach path indicators (PAPI) were operational. En-route weather was overcast with cloud tops at FL70 and a risk of icing. A pilot report of severe icing between FL30 and FL70 near Birmingham was noted. The terminal area forecast for East Midlands predicted a brisk north-easterly wind and a cloud base of 1200 feet. The aircraft departed at 17:25.
Flight Progression
The crew used the wing and tail de-icing system during climb to the assigned cruising level of FL90, remaining above the stratiform cloud layers. After an uneventful flight via Wallasey to the Whitegate NDB, radar vectors brought the aircraft directly toward the airport, with descent clearance to 3000 feet to intercept the ILS for runway 09. During descent, before entering cloud tops at about FL60, the crew activated the anti-ice system (windscreen, engine air intakes, propellers, static vents, and pitot probes) but, per normal procedure, did not use the wing and tail de-icing system. At this time, the freezing level was at 1000 feet, temperature at FL60 was -6°C, and the air was saturated.
Loss of Control
While in dense cloud, ice thrown from propellers was heard striking the fuselage. The crew suggested increasing propeller rpm to expedite ice removal. Both pilots visually checked for ice during descent but saw none. Other flights that evening later reported severe icing. After leveling at 3000 feet, still in and out of cloud, the aircraft intercepted the ILS and was established on glideslope and centerline by 10 nm. The final descent was initiated.
A normal approach continued past the outer marker at 3.9 nm down to about 1000 feet above runway threshold. The crew reported no significant turbulence or visible ice up to that point. The last wind information given was 060°/15 kt, although wind speeds in the area had gusted up to 30 kt over the previous hour.
As the aircraft descended through about 1000 feet, it suddenly rolled sharply left without apparent cause. Corrective aileron and rudder input caused a rapid roll to the right, well beyond wings level. Alternate left and right rolling continued, with increasing bank angles over approximately 30 seconds, leading the commander to believe the aircraft might roll onto its back. The oscillations then gradually decreased. During this period and shortly after, the aircraft established a high descent rate approaching 3000 ft/min.
Impact and Evacuation
With full engine power, airspeed increased and the rate of descent was arrested just as the aircraft struck an 11 kV power cable. It continued through another similar cable, two supporting wooden poles, and the tops of two trees before coming to rest nose-first in a small wood bordering a barley field, approximately 460 meters from the first cable impact. The cockpit and passenger cabin were largely undamaged, and there was no fire. The aircraft came to rest virtually upright, and all occupants evacuated successfully from the front and rear emergency exits.
Probable Cause
The accident most probably occurred as a result of the effects of a significant accumulation of airframe ice degrading the aircraft's stability and control characteristics, such that the crew were unable to maintain control. Turbulence and/or downdraught may have contributed to the accident. Other contributory factors were the difficulty in detecting clear ice at night on the SD3-60 which resulted in the airframe de-icing system not being used. The delay in application of go-around power may have also contributed to the accident.