When a pilot experiences CAT , a number of rules should be applied : Because aircraft move so quickly , they can experience sudden unexpected accelerations or ' bumps ' from turbulence , including CAT - as the aircraft rapidly cross invisible bodies of air which are moving vertically at many different speeds . Although the vast majority of cases of turbulence are harmless , in rare cases cabin crew and passengers on aircraft have been injured when tossed around inside an aircraft cabin during extreme turbulence ( and in a small number of cases , killed , as on United Airlines Flight 826 on December 28 , 1997 ) . BOAC Flight 911 broke up in flight in 1966 after experiencing severe lee-wave turbulence just downwind of Mount Fuji , Japan
BOAC Flight 911
BOAC Flight 911
Clear-air turbulence