(Newser) – A Qantas flight from Los Angeles to Melbourne plummeted into a 10-second nosedive a few days ago that left passengers terrified, Australia's News Network reports. Seems flight QF94 ran into a "vortex" or "wake turbulence" caused by a flight that had left two minutes before. "It was between 1½ and two hours after we left LA and all of a sudden the plane went through a violent turbulence and then completely up-ended and we were nose­diving," says passenger Janelle Wilson. "We were all lifted from our seats immediately and we were in a free fall. It was that feeling like when you are at the top of a roller coaster and you’ve just gone over the edge of the peak and you start heading down. ... It was terrifying."

Flight QF12 left LA on Sunday night at 11:27pm after a 57-minute delay, and QF94 followed two minutes later after a 49-minute delay—but a Qantas spokesperson insists that separation standards were upheld to keep the A380 aircraft at a distance of 20 nautical miles apart. "There are safeguards in place to reduce the likelihood of wake turbulence encounters, but it is hard to eliminate," says Qantas, per the Daily Mail. "Unexpected turbulence is why we always recommend passengers keep their seat belt firmly fastened at all times." The flight arrived safely in Melbourne, if 30 minutes late. (See a fuller description of "wake turbulence" at Skybrary, or read about an airline that ditched windows in first class.)

