three turbulence-related deaths since 2003 , Boeing says . three of the At least two were people not wearing seat belts . It 's a moment familiar to any regular air traveler . Turbulence is caused by quick changes in air movement . Air pockets from `` clear-air '' turbulence are hard to detect .
three turbulence-related deaths since 2003 , Boeing says . three of the At least two were people not wearing seat belts . Turbulence is caused by quick changes in air movement . Air pockets from `` clear-air '' turbulence are hard to detect .