What happened
On October 21, 2002, a Japan Airlines flight operating a Boeing 747-40/D, registration JA8903, was descending toward Tokyo International Airport when it encountered extreme atmospheric disturbances. While flying at approximately 39,000 feet over the sea, roughly 8 nautical miles southeast of Hamamatsu City, the aircraft was subjected to sudden, violent shaking.
The intense turbulence and subsequent aircraft motion led to three serious injuries among passengers and one serious injury to a cabin crew member. Additionally, 18 passengers and 11 cabin crew sustained minor injuries. The force of the event was significant enough to cause partial damage to the aircraft's cabin interior.
The investigation
The investigation, conducted by the Aircraft and Railway Accidents Investigation Commission, focused on the sequence of aerodynamic changes and the crew's response to the turbulence. Investigators analyzed data from the Digital Flight Data Recorder (DFDR) and Cockpit Voice Recorder (CVR), alongside meteorological reports and radar imagery.
Specialized research was performed to examine the longitudinal flight control system of the Boeing 747-400D, specifically looking at how the autopilot and manual elevator controls reacted to rapid airspeed fluctuations. Numerical simulations and flight simulator tests were also utilized to understand the aircraft's motion and the vertical accelerations experienced in the cockpit and aft cabin during the event.