Investigators: High winds, rotor flap caused fatal Kauai helicopter crash

Associated Press

5 hours ago

A helicopter that crashed on Kauaʻi in July, killing the pilot and two passengers, broke up in-flight after it hit turbulence causing the main rotor blades to strike its airframe, National Transportation Safety Board investigators found.
The conclusion was made without data revealing the helicopter's final moments because it wasn't carrying a flight recorder that would have shown its altitude, airspeed and the last actions taken by the pilot.
But the final report contains new details of the high winds around the accident area that day and includes dramatic video footage capturing the weather front that rolled in just before the aircraft went down.
The Robinson R44 Raven II operated by Aloha Helicopter Tours plummeted into the ocean off Kauaʻiʻs Nāpali Coast just after 1 p.m. July 11, 2024, after it broke in half during a one-hour sightseeing tour.
Hikers on the Kalalau trail who had stopped to take photos of the coast told NTSB investigators that before the crash they felt a 'huge, huge gust of wind' strong enough to blow 'a 50-pound backpack off a rock.' They then heard a 'loud bang' and looked toward the noise to see the helicopter falling straight down, the tail section detached.
One witness said the drop took 3-4 seconds and the impact 'made a big, loud splash.'
The wreckage was recovered by the U.S. Coast Guard in 80 feet of water, but only one body was ever found — that of Amy Quintua, a Kentucky woman who was on the tour with her husband James.
An inspection of the wreckage did not show any mechanical irregularities, the NTSB accident investigators said, but they did find evidence that the main rotor blades had hit the airframe — a condition known as 'mast bumping.'
The R44 is one of the world's most popular helicopters because of its affordability, but it also has a high rate of accidents because its rotor blades are susceptible to extreme flapping under certain conditions. Between 2006 and 2016 it had the highest fatality rate of any helicopter flying.
During downdrafts and high winds, the twin blades mounted on a mast above the main cabin can start to oscillate violently up and down. If pilots don't reduce their airspeed or overcorrect the flying controls, the flapping rotors can strike the tail or cabin and result in mid-air disintegration — which was the NTSB's finding in this case.
NTSB investigators found mast bumping on an R44 was also the cause of a 2019 crash over Kailua in which three people died.
The manufacturer Robinson issued its own safety notice about the problem, and the Federal Aviation Administration requires pilots to complete a pilot safety course before flying certain Robinson models including the R44.
The 69-year-old pilot who died in the Kauaʻi accident, Guy Croydon, had completed a Robinson Helicopter Pilot Safety Course in 2011, was an experienced certified flight instructor and had passed his last flight review two weeks prior to the accident, the report said.
His body was not recovered, however, so a toxicology report could not be conducted.
Investigators pointed to the likelihood of weather as a contributing factor in their preliminary report last year, and the detailed study found the weather in the area on July 11 was conducive to the development of strong downdrafts.
Limited radio location data shows the flight path of the helicopter up until 10 minutes before the crash.
The helicopter briefly rose to an altitude of 3,500 feet where wind speeds reached about 44 mph, the tracker shows. Easterly winds over the accident site were estimated at 30 to 37 mph over the accident site, the NTSB's weather study found.
The manufacturer's handbook for R44 pilots prohibits flight when the surface winds, including gusts, exceed 25 knots, or nearly 29 mph.
A week before the accident the National Transportation Safety Board had written to the chairman of the FAA about its continued concerns that some air tour operators and pilots in Hawaiʻi had adopted 'risky weather-related operating practices.'
The NTSB has been pushing the FAA to provide stronger oversight of the island state's busy air tourism industry, especially since 2019, when seven people died in a helicopter crash on Kauaʻi after the pilot continued to fly despite deteriorating weather and poor visibility.
During the investigation into that crash, NTSB investigators heard testimony about a local culture among air tour operators of 'pushing the weather' — even when flying conditions are not optimal. Local Industry representatives have told Civil Beat that pilots always have the final say in whether to go up.
Video footage from one of a new network of weather cameras installed last year by the Federal Aviation Authority to help tour operators assess conditions along the flight path captured the rapid changes in cloud cover and visibility at the time of the accident.
The decision to fly or not fly underpins a lawsuit filed in March against the tour operator Aloha Helicopter Tours LLC doing business as Ali'i Air Charters by the estates of the two passengers who died.
The filing in the Maui District Court alleges the companies and its employees were negligent in not monitoring the weather prior to takeoff, properly assessing the risk of flying into inclement weather, and failing to abort the flight.
An attorney for the plaintiffs Jacob Lowenthal said Friday that the weather data in the final NTSB report will be a critical component of their case.
Another Aloha Helicopter Tours pilot, Felipe Victoria, who flew over the site about 30 minutes after the accident, told Federal Aviation Administration inspector Seth Cossel that he had called Croydon during his lunch break to ask if he was going up for his afternoon flights.
Croydon said he was, and this helped Felipe inform his own decision to keep flying that day. 'It was Guy's next flight after lunch that was the accident flight.'
Reached by phone Friday the owner of Aloha Helicopter Tours, William Zeffiro, said his attorney had advised him not to comment on the lawsuit or the report.
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This story was originally published by Honolulu Civil Beat and distributed through a partnership with The Associated Press.