Unexpected turbulence is very real and not rare.

If you're seated and buckled up and the plane should drop suddenly, your seatbelt will keep you from flying around the cabin. There's nothing like a broken neck from slamming your head against the ceiling at 30 MPH to ruin your day...

Many people have died in this fashion; plenty of others have sustained very serious injury. To be honest, 35,000 above the Pacific and three hours from Anchorage is not the place I'd want a life-threatening injury requiring immediate hospitalisation.

For my part, I cannot understand why people do not buckle up whilst seated on a plane. It's cost-free, it's not intrusive at all, and it's a no-brainer insurance policy against a very nasty possible outcome.