Good question. In 1973 I was onboard a military aircraft in south east asia and it was a smooth flight. When landing we hit like a hole and the aircraft fell hundreds/thousands of feet. The pilot was just able to pull the aircraft up and we hit the runway hard. Several of us were injured. But there was nothing to warn us then. Now just a few days ago this happened: https://www.hawaiinewsnow.com/2022/12/18/multiple-injuries-reported-after-plane-lands-honolulus-airport-following-apparent-turbulence/