Some passengers were terrified, convinced the plane was going down. One seasoned traveler said it was the roughest flight he’d ever taken. A woman on board felt like she was experiencing an earthquake.

At least two dozen people were taken to hospitals after a Delta Air Lines Inc. flight hit severe turbulence that forced it to make an emergency landing in Minneapolis. Delta Flight 56 was less than an hour into its nine-hour flight from Salt Lake City to Amsterdam when the pilots encountered “significant turbulence,