Thunderstorms add stress to flying and aircraft structures

Severe turbulence and wind gusts are just some of the hazards prevalent in and around thunderstorms. The break up in the air of a Cessna 210 on 7 December 2011 en route from Roma to Dysart in Queensland is a reminder to all pilots that to minimise the risk of structural damage or loss of control, thunderstorms should be avoided.

The pilot was conducting a private flight under visual flight rules when the outer sections of the wings and part of the tail separated. The ATSB investigation found that the aircraft had been structurally sound before the separation and no aircraft system defects were identified. The investigation showed that thunderstorms had been recorded in the area and cruise power setting had been maintained until an onboard engine monitoring system ceased recording.

Although the precise circumstances leading 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 speed (VA) 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 gust are encountered.

Related: Turbulence
Last update 19 March 2014