A Lufthansa flight that experienced “significant turbulence” late last week was diverted to Washington Dulles International Airport and seven people on board were taken to area hospitals.

Flight 469 from Austin, Texas, had been headed to Frankfurt, Germany, but landed safely evening at the airport in Virginia, Metropolitan Washington Airports Authority spokesman Michael Cabbage said.

Crews responded to the flight and took seven people to hospitals with injuries that were believed to be minor, Cabbage said.

The Airbus A330 reported severe turbulence at an altitude of 37,000 feet while flying over Tennessee, prompting an investigation from the US Federal Aviation Administration.

Passenger Susan Zimmerman, 34, of Austin, Texas, said one of the pilots told the cabin that the plane had fallen about 1,000 feet (305 m.) during the sudden turbulence.

“It felt like the bottom just dropped out from underneath,” she said. “Everything was floating up. For a moment, you are weightless.”

The brief but severe clear-air turbulence about 90 minutes after takeoff led to the unscheduled landing as a precaution, Lufthansa said in a statement. The passengers received medical attention and Lufthansa ground staff were working to rebook travellers, the airline said. There were 172 passengers.

“The safety and well-being of passengers and crew members is Lufthansa’s top priority at all times,” the statement said.

Turbulence continues to be a major cause of accidents and injuries during flight, according to a 2021 National Transportation Safety Board report. Turbulence accounted for 37.6% of all accidents on larger commercial airlines between 2009 and 2018.

Turbulence is essentially unstable air that moves in an unpredictable fashion. Most people associate it with heavy storms. But the most dangerous type is clear-air turbulence, which can be hard to predict and often gives no visible warning in the sky ahead.

Storms has been moving areas of Tennessee at the time, creating strong winds in the upper atmosphere, said Scott Unger, a senior forecaster with the US National Weather Service in Nashville.

“It was very windy aloft, which could easily lead to the possibility of turbulence with any flight,” he said.

The turbulence hit during the middle of meal service as passengers and crew were moving throughout the cabin, said Zimmerman, who is five months pregnant. She said she still had her seatbelt on and that neither she nor her baby were injured.

“I’m pretty sure she slept through it,” she said. “She’s surrounded in amniotic fluid.”