On 16 December 2007, a Bombardier CRJ-200 being operated by Air Wisconsin on a scheduled passenger flight from Philadelphia, PA to Providence RI made an ILS approach to Runway 05 at destination in Instrument Meteorological Conditions (IMC) which became unstable but was continued to an extremely hard night touchdown which broke the left hand main landing gear and was followed by exit of the aircraft from the left hand side of the runway and a slide through a snow-covered grassy area before it came to a stop without impacting any obstructions. There were no injuries to the occupants, who left the aircraft using the integral air stairs at the main door but the aircraft suffered “substantial” damage.
An Investigation was carried out by the National Transportation Safety Board (USA) (NTSB). It was established that the PF for the approach was the First Officer who had “had very little instrument approach experience in the CRJ-200”. Both the autopilot and First Officer’s Flight Director were found to have been disconnected at approximately 700 feet aal before visual reference with the runway was acquired at approximately 300 feet aal. The aircraft then drifted left of track and above the ILS GS taking it outside stabilised approach criteria. Upon becoming visual with the runway, both pilots became aware of the deviation and misalignment with the runway. The aircraft commander then offered to take over control “salvage the landing” rather than abandon it in favour of a missed approach. As he took control, the First Officer misunderstood a remark he made and reduced power to Flight Idle without his awareness which led to the development of a high sink rate. The Investigation account then observes that “due to the flare rotation and sink rate, the airplane exceeded the stall angle of attack, and the stall protection system (stick shaker and pusher) briefly activated.”
A performance study carried out as part of the Investigation found that the touchdown had occurred with the aircraft on runway heading with about a 9° left bank an a sink rate of approximately 1100 fpm. After the runway excursion, the aircraft had ended up on a north westerly heading about 115 metres from the landing runway threshold.
The high vertical speed at touchdown exceeded the certified load limit for the landing gear which failed. No evidence of any pre-existing damage to the gear components was subsequently found with the collapse and separation of the gear assembly occurring in accordance with system design.
It was noted that at the time of the accident, the Operator had no prohibition against making a raw data approach to minimums and that prevailing SOPs provided little in the way of mandate or guidance to crews in respect of their determination of when a go-around would be necessary.
The NTSB determined that the probable cause of this accident was that “the landing gear collapsed during landing for undetermined reasons.” It also noted that “contributing to the accident was the first officer’s poor execution of the instrument approach, and the lack of effective intra-cockpit communication between the crew. Additional contributing factors to the accident are the lack of effective oversight by (the Operator) and the FAA to ensure adequate training and an adequate experience level of first officers for line operations.”
The Final Report was approved on 28 May 2008 and may be seen in full at SKYbrary bookshelf: DCA08FA018
No Safety Recommendations were made.