The 777 was flying from London to Singapore when it hit the turbulence.
A British man died and authorities say he likely had a heart attack.
One passenger said a lot of people who were not buckled up hit their heads on the overhead bins.
ABC11 spoke with John Nance who is an ABC News aviation expert and retired airline pilot about what to do when turbulence strikes.
He said it's important to always be buckled-up when we're flying because turbulence often hits without warning.