Severe turbulence rocked a flight from Phoenix to Honolulu, seriously injuring 11 people in what a Hawaiian Airlines official called an isolated and unusual event.

Jon Snook, the airline’s chief operating officer, said the airline hasn’t experienced “an incident of this nature in recent history”. The Sunday flight was full, carrying 278 passengers and 10 crew members, he said during an afternoon news conference.

Jim Ireland, director of Honolulu Emergency Medical Services, said 20 people were taken to hospitals, including 11 people deemed to be in serious condition.

At least one person was reported to have been rendered unconscious but all patients were awake and talking when they arrived at hospitals, he said.

Patients suffered cuts, including to the head, as well as bumps and bruises. In addition, he said some people were nauseous and vomited as a result of extreme motion. Altogether 36 people received treatment.

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Thorough inspection

Thomas Vaughan, a meteorologist with the National Weather Service in Honolulu, said there had been a weather advisory for thunderstorms that included Oahu and areas that would have included the flight path at the time of the incident.

The airline was aware of the weather forecast and the unstable air and weather conditions, but had no warning the particular patch of air where the turbulence occurred “was in any way dangerous,” Snook said.

He didn’t know how much altitude the plane lost during the turbulence, saying that would be part of an investigation involving the National Transportation Safety Board.

The plane’s flight data recorder would provide those details, he said.

The investigation would also address precisely what the passengers and crew were doing at the time. Snook said the aircraft would undergo a thorough inspection and maintenance, mostly to fix components in the cabin.

Snook said he could only speculate whether some passengers hit their heads, but that was likely based on the injuries and the damage to cabin panelling.

The investigation will examine what other measures were taken, aside from turning on the fasten seatbelt sign, to ensure passengers were buckled in, he said.

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