Passengers said they thought they were going to die as they were hurled over seats and slammed against luggage bins when turbulence hit their flight from Brazil to the US.
Some people were asleep and others snacked when the first turbulence rattled Continental Flight 128 over the Atlantic yesterday. Suddenly, the jet began to plunge and shake violently.
The Boeing 767 made an emergency landing in Miami, Florida, so at least 26 injured people, four of them in a serious condition, could receive medical help.
But the sudden turbulence that rocked the overnight flight from Rio de Janeiro to Houston, Texas, was an all-too-real reminder of an Air France flight - also travelling from Rio - that crashed into the mid-Atlantic in June during thunderstorms, killing all 228 people on board.
"I immediately thought of the Air France flight, that we're going to fall. We're going to fall," said Herman Oppenheimer of Rio, one of 179 people on the flight.
Camila Machado, 20, said: "I felt like the airplane was going to crash. I felt like we were going to die. Like, the first thing I thought about was Air France."
Flight attendants in the aisle were thrown against the ceiling. Passengers who were not belted in went flying into the overhead compartments; one woman hit a luggage bin so hard that her head stuck there. Oxygen masks dropped. A child smacked his chest on a tray table and started bleeding.
"One lady, she just came out of her seat and flew over the middle row, hit her head on the wall and landed on her back," said 13-year-old passenger Diego Saavedra, whose nose was bandaged as he spoke at Miami International Airport.
"All of a sudden there were people coming up off their seats, people screaming, little kids crying, people saying please, help please," Diego said.
Photos taken by a passenger showed overhead lighting compartments that had been cracked by the impact of passengers' heads; another photo showed the guts of an entire panel hanging down, the oxygen tanks inside exposed.
Aloiso Dias said he grabbed the seat in front of him and held on.
"I felt like I was on a rollercoaster. I couldn't even see what was going on with my wife," he said.
Passengers said the terror lasted only a few seconds. A doctor sitting in first class made the rounds through the aircraft and helped the injured, while the decision was made to land the plane in Miami so the injured passengers could be treated.
Federal Aviation Administration spokeswoman Kathleen Bergen warned against drawing any parallels between the two flights and said the cause and severity of the turbulence in the Continental case was still being investigated.
Meteorologists differed on weather conditions at the time the plane encountered the turbulence just north west of Puerto Rico.
Henri Agramonte, an assistant forecaster at the Dominican Republic national office of meteorology, said there were thunderstorms early yesterday, which were caused by a tropical wave that could have generated strong winds off the country's northern coast.
But Brian Wimer, a meteorologist from the State College, Pennsylvania-based Accuweather, said there were no thunderstorms in the area.
Mr Wimer speculated that the plane may have encountered clear air turbulence, which occur at high altitudes in tranquil and cloudless conditions.
"There's really no easy way to detect that," said Wimer. "It can cause problems if it's severe enough. Normally, if the pilots are aware of it, people sit down and belt in."
Aviation experts say air turbulence is rarely more than a nuisance, but it was responsible for 22% of all US airline accidents and 49% of serious-injury accidents between 1996 and 2005, the National Transportation Safety Board said in an annual safety review in March.
Unexpected turbulence is why pilots often tell passengers to keep their buckles fastened even if they have turned off the "seat belt" sign and the skies are clear.