N393HA

HISTORY OF FLIGHTOn December 18, 2022, about 1007 Hawaii standard time, Hawaiian Airlines flight 35, an Airbus A330-200, N393HA, was operating at FL400 about 65 nautical miles northnortheast of Kahului, Hawaii, when the airplane encountered severe turbulence. Of the 2 flight crewmembers, 8 flight attendants, and 283 passengers (including 2 off-duty Hawaiian Airlines pilots in the cockpit jumpseats and 3 lap-held children) aboard the airplane, 4 occupants (1 flight attendant and 3 passengers) sustained serious injuries, and 20 occupants (3 flight attendants and 17 passengers) sustained minor injuries. The airplane sustained minor damage. The regularly scheduled domestic passenger flight was operating under the provisions of Title 14 Code of Federal Regulations Part 121 from Phoenix Sky Harbor International Airport (PHX), Phoenix, Arizona, to Daniel K. Inouye International Airport (HNL), Honolulu, Hawaii.

The captain was the pilot monitoring, and the first officer was the pilot flying. The captain stated that the airplane was in visual meteorological conditions at FL400 and was above a cloud layer between FL370 and FL380. The captain stated that flight conditions were smooth with clear skies above the cloud layer and that the onboard weather radar displayed no returns.

According to the CVR, at 0955:57, air traffic control (ATC) advised the flight crew of a nearby airplane to go around weather due to reported turbulence that was ahead. Another flight crew (Hawaiian Airlines flight 45) reported continuous moderate chop.

At 0958:22, a flight attendant aboard the accident airplane made a passenger announcement that the airplane would be landing in 45 minutes and that passengers who wished to use the lavatory should do so at that time. At 1000:43, ATC advised the flight crew that “moderate to extreme precipitation and turbulence” and “light to moderate chop” would be occurring for the next 40 miles. About 31 seconds later, ATC advised the flight crew of another Hawaiian Airlines airplane (flight 11) that cloud tops were at FL410 with “light chop and moderate turbulence.”

During a postaccident interview, the captain stated that a cloud that looked like a “plume” appeared vertically in front of the airplane. The captain also stated that he set the weather radar to “elevation mode” (which allows the radar antennas to be tilted at different angles to scan the atmosphere), but the flight crew saw “nothing” displayed on the weather radar screens. At 1007:07, a flight crewmember stated, “it’s moving fast” and that the airplane should “clear most of it.” About 15 second later, the flight crew called the lead flight attendant to let her know to expect a “bumpy” ride shortly. At 1007:31, the flight crew noted, “it’s building fast.”

At 1007:43, the CVR recorded sounds, including rattling, that were consistent with a turbulence encounter. Sounds associated with autopilot disconnection and engine indicating and crew alerting system (EICAS) chimes were also recorded. The crew reacted to the turbulence with surprise, confirmed pilot control of the airplane, and reengaged the autopilot. Also at 1007:43 and then at 1007:59, an altitude alert sounded for about 1.5 seconds.

Data from the airplane’s quick access recorder showed that, at 1007:42 (1 second before indications of a turbulence encounter were recorded on the CVR), the airplane’s altitude increased by 68 ft (40,020 to 40,088 ft), and its vertical acceleration was 0.69 G. At 1007:43, the airplane’s altitude further increased by 248 ft (40,088 to 40,336 ft), and the airplane’s vertical acceleration was 1.27 G. The quick access recorder data also showed that, at 1007:44 (when the autopilot disconnected), the airplane’s vertical acceleration was 2.18 G. One second later, the master caution and master warning became active. At 1007:46, the vertical acceleration had decreased to -0.98 G.

At 1008:12, a flight attendant made an announcement for passengers to be seated and fasten their seatbelts. Between 1008:14 and 1009:11, the CVR recorded additional EICAS chimes. During that timeframe (at 1008:54), the lead flight attendant notified the flight crew that medical assistance would be needed upon landing.

At 1010:06, the CVR recorded the flight crewmembers stating that they should have “gone around it.” The flight crew also communicated with a flight attendant, who confirmed injuries in the cabin that needed medical attention. The flight attendant also stated that the cabin interior “doesn’t look good.”

At 1010:41, the flight crewmembers discussed the event, stating that they thought that the airplane would have cleared the cloud formation but that it “came up real fast.” One crewmember questioned, “did it just pop up?”. At 1013:43, the flight crew made a passenger announcement about the turbulence encounter. Less than 1 minute later, the flight crew contacted Hawaiian Airlines dispatch to inform the operator about the turbulence encounter. The crew stated that the airplane “hit 40 degrees of bank” and that passengers had been injured. The crew requested medical assistance for those with injuries and estimated that the airplane would be arriving at HNL at 1045. Shortly afterward, the flight crew notified ATC that the airplane had started its descent, and the CVR recorded the flight crew performing descent checks.

At 1018:14, the flight crew informed ATC that the airplane encountered “severe turbulence” at FL400 and requested expedited handling to HNL. In response, ATC declared an emergency for the flight. At 1019:08, a flight attendant provided details to the crew about some passenger injuries and stated that, in the aft half of the cabin, the ceiling was damaged and oxygen masks had dropped. At 1020:52, the flight crew informed company dispatch about three confirmed injuries and stated that the airplane was “coming in as fast as [it] can.” Dispatch notified the crew that emergency medical services were alerted and ready. At 1024:17, the captain made a passenger announcement, indicating that he would keep the seatbelt sign illuminated after landing to allow emergency personnel to access those who were injured.

The CVR showed that, at 1025:44, the flight crew began to discuss what else they could have done regarding the event, but this conversation was mostly unintelligible because of an overlapping unrelated radio transmission. At 1026:35, the crew noted that the cloud formation was not depicted in red (high reflectivity) on the weather radar display and that the formation had “caught them completely off guard.” About 2 minutes later, a flight attendant informed the flight crew that about 10 people were injured, and the flight crew then contacted company dispatch with the updated number of airplane occupants who would need medical attention.

As the airplane was descending to 10,000 ft, ATC told the crew to expect the instrument landing system approach to runway 4R. Afterward, the crew performed the in-range checklist. At 1033:55, the flight crew discussed the airplane’s earlier attitude, indicating that “we went at least 40 degrees…maybe more” and that the airplane “kicked off everything.” The crewmembers then stated that they had just practiced a similar upset event in the simulator.

Between 1035:31 and 1036:52, ATC instructed the flight crew to turn onto a left heading of 220° and cleared the airplane to an altitude of 6,000 ft. At 1039:15, ATC cleared the airplane to 1,500 ft, and another discussion about the turbulence encounter ensued, with the flight crew stating that the plume “came out of nowhere” and that “nothing” was displayed on their weather radar screens. ATC continued to vector the airplane toward HNL and cleared the airplane for the approach.

The flight was then handed off to the HNL tower, and the crew contacted the tower at 1043:21. The tower controller cleared the airplane to land on runway 4R, and the crew performed the before landing checklist. The CVR recorded sounds consistent with touchdown at 1046:26. About 30 seconds later, the flight attendants made an announcement for passengers to remain seated to allow medical personnel to board. (This announcement was repeated at 1051:50 and 1053:18.)

At 1048:44, the flight crew discussed the turbulence encounter again, and one of the crewmembers stated that it reminded him of a “volcanic explosion” and that the upset was “the most unusual attitude” he had experienced. This crewmember was thankful that the seatbelt sign was on at the time of the encounter. At 1058:57, the captain reminded the passengers to remain seated.

At 1100:03, the flight crew ran the parking checklist. At 1100:20, one of the flight crewmembers visually confirmed that the cabin had structural damage. At 1100:59, the flight crew resumed discussing the turbulence encounter, stating that the clouds were “kinda flat” but that, once the airplane was closer to the clouds, “it built super fast.” The crew also noted that, even though the airplane “dumped everything,” including the autopilot and authothrottle, all electrical systems stayed on. At 1102:39, the flight crew discussed that about 12 people were injured. The CVR recording ended at 1103:50. AIRCRAFT INFORMATIONThe airplane was configured with 2 pilot seats, 2 cockpit observer seats, 11 flight attendant seats, and 278 passenger seats. Three of the 283 passengers on the accident flight were lap-held children, and two off-duty Hawaiian Airlines pilots were in the cockpit observer seats. METEOROLOGICAL INFORMATIONThe weather document attached to the dispatch release included the departure, destination, and alternate airport meteorological aerodrome reports, terminal aerodrome forecasts, and notices to air missions. The document also included the SIGMETs and AIRMETs that were current when the flight was released at 0141 (0441 mountain standard time).

According to the release flight dispatcher, the captain of the accident flight had contacted flight dispatch at 0233 (0533 mountain stan...