Continental Flight 75 had been in the air maybe an hour, 150 miles out from Los Angeles on the way to Hawaii when it hit the turbulence and the nightmare began.

"The plane just immediately fell," said Adam Paul, 25, of Provo, Utah. "It felt like we'd fallen three to four stories. People were glued to the ceiling - and then they just dropped."The DC-10 dipped and then plunged sharply Thursday afternoon, injuring seven of the 283 people on board and forcing the plane to return to Los Angeles. No one was killed, but the injuries included broken bones, from fractured legs to cracked jaws.

The flight encountered moderate to severe turbulence about 1:15 p.m., said Mitch Barker, Federal Aviation Administration spokesman. Airline spokesman Ned Walker said the jet carrying 270 passengers and a crew of 13 was climbing at 31,000 feet at the time - and the seat belt sign was on.

"I think the flight attendants probably got the brunt of it," said Dr. Brigeli Westerband, who treated two attendants at Daniel Freeman Marina Hospital.

One was a woman with a fractured jaw and ankle, and two men with broken legs were also treated at the hospital. A 45-year-old woman with a broken leg and a 41-year-old man with neck and back pain were treated at Centinela Hospital Medical Center in Inglewood.

Turbulence is unstable air that can make a jet bump, rise and fall. Storm clouds and mountain ranges can cause it, but there also are invisible, unpredictable areas of unstable air known as clear-air tur-bu-lence.

In March, hoping to prevent turbulence-related injuries, American Airlines and United Airlines announced they would require passengers to stay buckled up when they are seated.

FAA figures show that between 1981 and November 1996, two passengers were killed and 63 seriously injured in 252 incidents of turbulence reported by major U.S. air carriers operating worldwide.

In December, a United jet flying from Tokyo to Honolulu hit turbulence that killed one passenger and injured 83 others.