On 7 December 2011, the owner-pilot of a Cessna 210M, registered VH-WBZ, was conducting a private flight under the visual flight rules from Roma to Dysart in Queensland. Thunderstorms with associated cloud, rain and severe turbulence were forecast for the area. About 30 minutes into the flight the outer sections of the wings and parts of the tail separated. The aircraft collided with terrain, fatally injuring the pilot.
What the ATSB found
The ATSB established that the aircraft was structurally sound before the wing and tail sections separated. No aircraft system defects were identified. Ground-based weather radar showed thunderstorms in the vicinity of the accident site, and recorded engine data showed cruise power setting was maintained until recording ceased. Although the precise circumstances leading up to the accident were not known, a combination of aircraft airspeed with the effects of turbulence and/or control inputs generated stresses that exceeded the design limits of the aircraft structure.
Airspeed is a critical factor in the stress sustained by an aircraft. Pilots need to be aware of the manoeuvring (VA) speed for the aircraft weight, and to control the airspeed so as not to exceed that value when full control deflection is required or severe turbulence or wind/gusts are encountered.
Severe turbulence and wind gusts are just some of the hazards prevalent in and around thunderstorms. This accident is a reminder to all pilots that, to minimise the risk of structural damage or loss of control, thunderstorms should be avoided.