What happened
An aircraft was dispatched for flight despite having an inoperative airframe deicing system, even though such equipment was necessary for the anticipated icing conditions. During the descent toward the destination, the flight crew encountered light icing. Despite the known lack of deicing capability, the pilot proceeded with the descent.
As the aircraft transitioned to the ILS final approach, the crew observed a substantial buildup of ice on the airframe. To compensate, the pilot utilized an approach speed higher than standard procedures. Upon extending the flaps to the full 50° position, the aircraft experienced buffeting and a sudden nose-down pitch. The pilot attempted to correct the pitch with significant back pressure on the control column, but the aircraft struck the runway with high force. This impact caused the landing gear to collapse, resulting in the aircraft sliding approximately 3,600 feet before coming to a halt. There were no fatalities reported in the accident.
Findings
Investigation into the incident revealed that the crew had access to surface observations and terminal forecasts via the company computer, but they were unaware that an Area Forecast (FA) was available at their terminal. This specific forecast had predicted light to moderate rime and mixed icing in clouds and precipitation above the freezing level.
Evidence indicated that a tailplane stall occurred, which can cause a nose-down trim change when flaps are extended. Contributing factors included a lack of company training regarding cold weather operations, deficiencies in the management and use of deicing systems, and insufficient FAA surveillance. No mechanical anomalies were identified prior to the impact, other than the non-functional deice system.