The ATSB was advised of two turbulence related events that occurred on 5 July 2013 and 7 July 2013, involving VH-VZY and VH-QOP respectively.
On 5 July 2013, a Boeing 737 aircraft, registered VH‑VZY, departed Perth, Western Australia on a scheduled passenger service to Canberra, Australian Capital Territory. While descending through 8,000 ft, the aircraft encountered severe turbulence for about 2 minutes. The flight crew reported that they experienced difficulties with maintaining their assigned altitude of 7,500 ft for about 1 minute and the aircraft descended to 7,200 ft. A cabin crew member positioned in the rear of the aircraft sustained minor injuries.
On 7 July 2013, a Bombardier DHC-8-402 aircraft, registered VH-QOP, was being operated on a scheduled passenger service from Wagga Wagga to Sydney, New South Wales.
During the cruise, while in clear conditions, maintaining flight level (FL) 210, the aircraft experienced severe turbulence. The turbulence ceased for about 2 seconds and moderate turbulence was then experienced. The aircraft pitched upwards by 5°, the right wing dropped by 7°, and the airspeed increased by about 20 kt. The seat belt sign was turned on. Overall, the turbulence encounter lasted for about 6 seconds. It was reported that a passenger sustained a broken or dislocated ankle and a cabin crew member sustained an ankle injury.
Research conducted by the Australian Transport Safety Bureau (ATSB) identified that 99 per cent of people on board an aircraft receive no injuries during a typical turbulence event. However, passengers and cabin crew not wearing a seat belt can be thrown around without warning.