On December 28, 1997, Flight 826 was a Boeing 747-100 flying from Narita International Airport, Japan to Honolulu International Airport in Hawaii. Two hours into the flight, at 9400 meters (31,000 ft), the plane received reports of severe clear-air turbulence in the area and the seat belt sign was turned on. Moments later, the aircraft suddenly dropped around 30 meters (100 ft),^[2] seriously injuring many passengers, although there was no damage to the aircraft. The plane turned around and landed safely back in Tokyo, but was not put back in service since it had been scheduled to be retired in early 1998. One passenger died of her injuries after landing in Tokyo.^[3]

• http://en.wikipedia.org/wiki/United Airlines Flight 826