A September 1998 plane crash in Takatsuki, Osaka Prefecture, that killed all five people aboard was the result of the aircraft going into a “graveyard spiral,” a Transport Ministry task force concluded Friday.
A spiral is an attitude an aircraft can get into if the pilot loses spatial orientation. John F. Kennedy Jr.’s plane is believed to have gone into a spiral or a spin before it crashed off Long Island earlier this year.
In a report submitted to Transport Minister Toshihiro Nikai, the Aircraft Accident Investigation Commission said the plane started spiraling downward while the pilot was flying on instruments in clouds and disintegrated in midair.
A common occurrence that can lead to a graveyard spiral or fatal spin is when a pilot flying without outside visual references, such as at night or in clouds, has the mistaken sensation that the aircraft is banking when it is not, and then turns in the apparent opposite direction to stop the turn, causing the turn to accelerate into a spiral that is hard to get out of. This happens when the inner ear’s sense of balance becomes disoriented.
Getting out of a spiral in blind-flying conditions requires training and concentration on instruments. Attempting to only pull the nose up in a spiral can cause the turn to tighten and result in an accelerated stall. The aircraft may become overstressed to the point where it breaks apart.
Commenting on why the aircraft went into a spiral in Takatsuki, the committee said the pilot, Noriko Shibata, 32, of Shikatsu, Aichi Prefecture, was unfamiliar with instrument flight.
Although Shibata held a professional pilot’s license and had logged a total 3,200 flying hours, he logged no instrument flights during the preceding 180 days, as required by the Civil Aeronautics Law.
Hideki Ogura, a veteran helicopter pilot from Kani, Gifu Prefecture, who was reportedly sitting in the pilot’s seat at the time, had not flown during the previous 30 days.
Investigators could not determine which of the two men was in control of the aircraft at the time of the accident, according to the report.
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