What happened
On December 16, 2008, at 18:18 UTC, a Beechcraft B 300 Super King Air 350, registration F-GKYY, was performing a night approach at Orléans Saint-Denis-de-l’Hôtel. The aircraft, operated by Dexia Sofaxis, was flying from Toulouse Blagnac with a crew of two and seven passengers.
The flight crew was conducting a Locator approach to runway 23. During the approach, the aircraft entered a layer of clouds at approximately 1,800 ft and descended through 800 ft. As the pilot reduced power to execute the flare, the aircraft stalled at 40 feet above the runway, resulting in a heavy impact on the main landing gear. While the aircraft was able to taxi to the parking area, it sustained significant damage.
The investigation
The BEA investigation reconstructed the flight profile using the Cockpit Voice Recorder (CVR) and radio altitude announcements. Analysis of the descent rate showed that while the sink rate decreased between 100 ft and 50 ft, it increased significantly to approximately -1,200 ft/min at the moment of impact.
Investigators examined the aircraft's de-icing and anti-icing systems, noting that the aircraft was equipped with both preventive and curative systems, including pneumatic de-icing boots on the wing and horizontal stabilizer leading edges. Post-accident inspections revealed that the nose, wing leading edges, and winglets were uniformly covered in a roughly one-centimeter layer of hard, transparent, and rough ice.
Findings
- The aircraft encountered significant icing conditions; meteorological data indicated the presence of saturated stratus layers containing supercooled water at temperatures between -3 °C and -8 °C.
- Accumulated ice on the airframe altered the aerodynamic performance, specifically reducing the stall angle of attack.
- The crew was flying at a speed of approximately 110 knots, which was above the recommended Vref of 104 knots, but the presence of ice necessitated a higher approach speed.
- No stall warning or other alarms were triggered prior to the impact, likely because the ice accumulation had reduced the stall angle to a point below the threshold at which the stall warning system is set to activate.