On 23 September 2005, an AS350 helicopter, operated by Heli USA Airways, crashed into the sea off Hawaii following loss of control associated with flight into adverse weather conditions.
This is an extract of the Flight History from the official report into the accident published by the National Transportation Safety Board (NTSB) (USA)
"On September 23, 2005, about 1415 Hawaiian standard time, an Aerospatiale AS350BA helicopter…operated by Heli-USA Airways, Inc., of Las Vegas, Nevada, encountered adverse weather and crashed into the Pacific Ocean several hundred feet off the coast of Kailiu Point, near Haena, Hawaii, on the island of Kauai. The sightseeing air tour flight was operated under the provisions of 14 Code of Federal Regulations (CFR) Part 135 and visual flight rules (VFR) with a company flight plan in effect. Localized instrument meteorological conditions (IMC) prevailed in the vicinity of the accident site. Three passengers were killed, and the commercial pilot and two other passengers received minor injuries."
"The flight departed from Lihue Airport (LIH), Lihue, Hawaii, on the island of Kauai…for the intended 45-minute tour…" "The pilot reported that the weather and visibility were good during the initial part of the tour. The pilot stated that he flew the helicopter over the Na Pali Coast on the northern part of the island at 2,000 feet above ground level (agl) and that the weather along the coastline was clear and without rain. The pilot stated that he saw rain showers offshore as the flight approached Kee Beach and Kailiu Point on the northern part of the island" "…passengers said that their helicopter made no evasive maneuver, or any maneuver, before entering what they described as “a wall of pure rain and thick clouds.”…" "One passenger reported that he could not see anything in the heavy rain and that he was about to say something about this to the pilot when the pilot announced that they were turning back. The pilot said that he started a right turn over the beach and that, during the turn, the helicopter’s airspeed dropped to zero and the helicopter started to rapidly descend."
"…A pilot flying a tour for another operator said that he heard the mayday call over the common traffic advisory frequency (CTAF)5 and twice attempted to fly his helicopter in the Kee Beach area to try to locate the downed helicopter but was unable to do so because of poor visibility."
The probable cause of the accident was given as:
"The National Transportation Safety Board determines that the probable cause of the accident was the pilot’s decision to continue flight into adverse weather conditions, which resulted in a loss of control due to an encounter with a microburst…"
- NTSB Accident Report AAB-07-01, Aircraft Accident Brief: Weather Encounter and Subsequent Crash into the Pacific Ocean, Heli-USA Airways, Inc., Aerospatiale AS350BA, N355NT, Haena, Hawaii, September 23, 2005.