On August 21, two years ago in 2012, Asiana Airlines flight OZ231 encountered an incident resulting in injuries to three passengers while cruising at an altitude of 40,000 feet over Matsue City, Shimane Prefecture, Japan. The flight was operating the route from Honolulu to Incheon, utilizing an Airbus A330-300 (registration HL8258). There were 206 passengers and 14 crew members on board. At 3:17 PM, the aircraft experienced severe Turbulence, causing two passengers to suffer serious injuries and one to suffer minor injuries; however, the aircraft itself sustained no damage.

Last week, on July 25, the Japan Transport Safety Board released the <a href=http://jtsb.mlit.go.jp/jtsb/aircraft/detail.php?id=2052>accident investigation report. According to the report, the cause of the Turbulence was that the aircraft was passing through a cumulonimbus cloud area, where strong updrafts caused irregular changes in wind direction and speed.

The aircraft’s weather radar should have been capable of detecting this phenomenon, yet the pilots failed to notice that the radar was switched off. Furthermore, at that time, there were frequent communications between other aircraft operating in the same airspace and Tokyo Center regarding reports of cumulonimbus clouds and route changes. Had the pilots been monitoring the ATC communications properly, they would have noticed the Turbulence. Therefore, it is clear that the responsibility for this accident lies with the crew, due to a failure in monitoring the weather and instruments.

Below is a transcript of the data:

15:16:36 Angle of Attack (AOA) increased sharply. 38s Wind speed reached 34 knots, headwind. Aircraft airspeed reached M0.872, exceeding the maximum operating speed Mmo (M0.86). 40s Vertical acceleration 1.88G, SAT rose 4 degrees and lasted for 15 seconds. 41s Climb rate 3300ft/min. 42s Wind changed to left crosswind, speed 20 knots. Vertical acceleration 0.04G. 46s Wind changed to tailwind. 48s Captain disengaged the autopilot (Company regulations dictate the use of autopilot; subsequent manual flying actually increased the aircraft’s oscillation). 54s Captain pushed the control column, pitch angle reached -6.3 degrees, vertical acceleration -0.09G. 55s Tailwind speed reached 52 knots. In the following tens of seconds, the pitch angle reached a maximum of +14.8 degrees, right roll reached 30.2 degrees, and left roll reached 17.9 degrees. 17:13 Aircraft altitude reached 41100 feet.

End