The pilot of a Hawaiian Airlines flight rocked by severe turbulence last month says a cloud "shot up vertically" in front of the plane—much like a plume of smoke—mere seconds before the plane began shaking, reports NBC News. The pilot had no time to deviate, according to a preliminary report from the National Transportation Safety Board. He informed the lead flight attendant to expect turbulence, and that turbulence came within one to three seconds, per the New York Times. The Dec. 18 flight from Phoenix to Hawaii had 281 people aboard, and 25 of them were injured, six seriously.
While the National Weather Service had issued a warning for thunderstorms, the flight had been a smooth one in sunny skies until the turbulence. NWS officials say the weather event that caused the disturbance is rare, reports KOIN. “Some of these updrafts or upward motions can be 40 mph or more, so nothing can be there and then in a matter of minutes you can have a well-developed cloud in front of you,” says NWS meteorologist Derek Wroe. Passengers later reported that the plane had a sudden and severe drop in altitude, but the NTSB report—a final one is due in 12 to 24 months—did not provide details on that, notes Hawaii News Now. (Read more Hawaiian Airlines stories.)