A Hawaiian Airlines flight encountered severe turbulence after a “cloud shot up vertically” in front of the plane on Dec. 18, resulting in injuries to 25 people, a preliminary report from the National Transportation Safety Board said.
The independent federal agency released its report Friday on Hawaiian Airlines Flight 35, detailing the weather conditions at the time of the turbulence.
A Hawaiian Airlines Airbus A330 captain told investigators the plane was traveling at a flight level of about 40,000 feet above a cirrostratus cloud layer. Flying conditions were smooth with clear skies and the weather radar was on when a cloud shot up vertically like a plume of smoke in front of the plane within seconds, the report said.
There was not enough time to change course, the captain said. He called the lead flight attendant to tell her that the plane might be hit by turbulence. Then, for one to three seconds, the aircraft experienced “severe convectively induced turbulence”[ads1]; at approximately 10:07 a.m.
The plane — bound for Honolulu from Phoenix — was about 65 nautical miles north-northeast of Kahului at the time and about 40 minutes from landing at Daniel K. Inouye International Airport in Honolulu.
Shortly after the sudden turbulence, the lead flight attendant informed the flight crew that there were several injuries in the cabin. Of the 291 passengers and crew on board the plane, 25 people were injured. Of those injured, four passengers and two crew members were seriously injured, and 17 passengers and two crew members received minor injuries. The aircraft sustained minor damage.
Investigators conducted a post-accident survey of weather in the area that revealed an “occluded frontal system with an associated upper-level trough moving toward the Hawaiian Islands. Satellite and weather radar imagery and lightning data depicted strong cells in the vicinity of the aircraft, the report said.
Also at the time of the incident, the US National Weather Service had issued a significant meteorological warning for “embedded thunderstorms with tops reaching FL 380 (aeroplane level of 38,000 feet)” over the region.
The preliminary NTSB report indicated prior to the incident that there were no pilot reports of severe turbulence along the route.
An NTSB spokeswoman said an investigation typically takes a year or two to complete, when a final report on the probable cause is expected to be released. A Hawaiian Airlines spokesperson declined to comment on the agency’s preliminary report because of the ongoing investigation.
NTSB Preliminary Report – HA Flight 35 by Honolulu Star-Advertise on Scribd