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N594BK accident description

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Crash location Unknown
Nearest city Mt. Waialeale, HI
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Tail number N594BK
Accident date 25 Jun 1998
Aircraft type Eurocopter AS-350-BA
Additional details: None
No position found

NTSB Factual Report


On June 25, 1998, about 0932 hours Hawaiian standard time, a Eurocopter, AS-350-BA, N594BK, operated by Ohana Helicopter Tours, collided with steep upsloping mountainous terrain near Mt. Waialeale, on the island of Kauai, Hawaii. Instrument meteorological conditions (IMC) existed in the vicinity of the accident site. The helicopter was destroyed, and the commercial pilot and the five passengers were fatally injured. A visual flight rules (VFR) company flight plan was filed with the operator. The accident occurred during an on-demand air taxi sightseeing flight that was performed under 14 CFR Part 135. The flight originated from the Lihue Airport, Kauai, about 0843.

The tour operator's president indicated that the purpose of the flight was to provide the fare-paying passengers with an aerial tour of the island of Kauai. The route of flight had previously been established, and it was known by the operator as its "Mokihana" tour route. This route circumnavigates the island, and provides for viewing specific topographical features. The flight normally lasts 48 to 50 minutes.

The operator's president reported that on June 25, it commenced flight operations for the day upon the departure of its three AS-350 helicopters from the Lihue Airport. The Lihue air traffic control personnel indicated that the helicopters took off in trail about 0840, 0842, and 0843. The helicopters' registration numbers were, respectively, N592BK, N593BK, and N594BK.

The operator's president also reported that the helicopters were scheduled to fly identical tours. Piloting the first helicopter was the company's chief pilot. The company's second most experienced line pilot flew the second helicopter, and the accident pilot, who had been employed for about 2.5 months, was the last to depart.

The pilots flying the first and second helicopters reported that they maintained radio contact with each other and with the accident pilot throughout their flights. At no time did they hear any indication from the accident pilot that he was experiencing any mechanical problems with the helicopter. These pilots reported to the National Transportation Safety Board investigator that they believed their flights had been performed in a manner consistent with the operator's previously anticipated route of flight. No unusual conditions were encountered. The first and second helicopters landed back at the Lihue Airport about 0929 and 0931, respectively. Neither of the pilots reported having observed the accident.

Minutes prior to the crash the company pilot flying the second helicopter was in radio contact with the accident pilot. Subsequently, the second pilot made a statement to the Safety Board investigator regarding his recollection of these communications, as follows:

He reported that, by regulation, he had announced his position using the common aircraft radio frequency by stating "three bravo kilo north wall." At this time it was about 0920. Light to moderate intensity rain was falling but the rain stopped at the mouth of the crater. The ceiling was about 3,000 feet mean sea level (msl) at the crater's entrance. The second pilot indicated that it took him about 2 minutes to fly in and out of the crater. The rain intensity was increasing and was becoming heavy as he was leaving. At this time he heard the accident pilot broadcast his position by stating that the "Hanalie ridge (about 3 miles north of the crater) does not look so good." The second pilot responded, "Chuck when I came across it it was light rain and the ceiling was good."

About 3 minutes later, the second pilot heard the accident pilot say "Boy the weather is looking bad right here." In reply to this remark, the second pilot stated "Chuck take a heading of one hundred twenty (a southeasterly course of 120 degrees) take your time." Review of an aeronautical chart revealed this heading would have taken the helicopter away from the mountains.

The second pilot subsequently gave the Safety Board investigator a written statement. In this statement the pilot provided a drawing showing his tour route, and additional information about his recollections during the flight.


The accident pilot held a commercial certificate with rotorcraft-helicopter and instrument helicopter privileges. His total flight time was about 3,170 hours. His experience flying the accident model of helicopter was about 220 hours, and this flight time was acquired during flights in the 90-day period that preceded the accident.

The pilot's personal flight record logbook was not provided to the Safety Board investigator for examination. A family member reported that it was not located.

In November 1997, the pilot retired from the armed forces of the United States after 20 years of service. In his subsequent employment resume for a civilian job, he indicated that he had experience flying H-3 Sikorsky helicopters and had functioned as a safety officer and an instrument check pilot. He was knowledgeable of the Hawaiian Islands having been stationed on Kauai for 2.5 years.

After the pilot completed the operator's training program, on April 10, 1998, the pilot passed a Federal Aviation Administration (FAA) administered 14 CFR Part 135 Airman Competency/Proficiency examination conducted by an FAA inspector. A Eurocopter, AS-350, was used during the flight test. Thereafter, the pilot assumed the duty position of pilot-in-command with the operator.


Equipment and Certification.

The helicopter was equipped with flight instruments, including an attitude indicator (artificial horizon), and other gyroscopic instruments including a directional gyroscope (DG) and a turn coordinator. Regarding navigational instruments, the helicopter was equipped, in part, with a very high frequency omni directional range (VOR) receiver. Also, the helicopter was equipped with a transponder having Mode C (altitude reporting) capability. The FAA authorized operation of the helicopter only under visual flight rules.

History and Maintenance.

The helicopter was manufactured in December 1993. Its total airframe time was about 6,875 hours. The helicopter had been operated about 35 hours since receiving its last 100-hour inspection on June 18, 1998.

On June 24, after the last flight prior to the accident, the helicopter was inspected by company maintenance personnel in accordance with their "daily check" procedure. No outstanding squawks or deficiencies were noted in the records, and no maintenance was performed. In the maintenance log, there was no reference to the Mode C transponder being inoperative.

The FAA participant reviewed the maintenance records and reported that all pertinent airworthiness directives had been complied with. A series of record keeping and procedural deficiencies were noted. These events were documented by the inspector in his "Inspector's Statement."


Between 30 and 45 minutes after the accident, one of the operator's tour pilots reported receiving the signal of an emergency locator transmitter (ELT). This pilot proceeded to pass by the general accident site area but was unable to observe the crashed helicopter due to the low level of clouds.

Local Weather Conditions.

The accident site is about 1 nautical mile (nm) east of Mt. Kawaikini's peak, elevation 5,243 feet msl, which is about the highest elevation on Kauai. The area is known as being one of the wettest locations on earth, and records annually over 400 inches of rain.

The accident helicopter collided into a mountainside south of the Waialeale Crater. The pilot flying the lead helicopter reported to the Safety Board investigator that during his flight he had observed the center of the island was covered with clouds, and rain showers were prevalent. The pilot said it was a typical weather condition for the area. In the area of the north wall of the Waialeale Crater there was a 2,500-foot ceiling. The pilot further indicated that due to the low ceiling and the rising terrain in the crater, he did not fly as far into the crater as usual. He encountered heavy rain showers and low clouds after exiting the crater.

Preflight Briefing and Operator Procedures.

According to Ohana's "Company Operations Manual-Helicopter," "The company pilot will, when requesting a weather report or forecast, use the services of the U.S. National Weather Service or a source approved by the FAA. If such a report is unavailable under VFR, the Pilot in Command may use weather information based on his own observation or of those who are competent to supply appropriate observations."

This internal company policy differs from that which the FAA required for the obtainment of aeronautical weather information. In the operator's FAA approved "Operations Specifications," the following procedure is mandated: "Pilot calls National Weather Service, Lihue or Honolulu Flight Service Station for current and forecast weather information when a pilot report is not available for the intended area of operation within the past two hours."

The Honolulu Automated Flight Service Station reported that no services were provided to the accident aircraft on June 25, 1998. National Weather Service personnel reported to the Safety Board investigator that no services had been provided to the accident pilot.

The operator's chief pilot subsequently informed the Safety Board investigator that on the morning of the accident flight he only used an internet web site to obtain his weather information. The identified web site was not either of the Direct User Access Terminal (DUAT) vendors.

The operator's dispatcher reported that the accident pilot reported to work and proceeded directly to the accident helicopter. He did not visit the company office prior to takeoff on the accident flight.

Weather Conditions at Lihue Airport.

The closest aviation weather observation station to the accident site is located at the Lihue Airport. The airport's elevation is 153 feet msl.

At 0840, an amended weather forecast was issued for the Lihue Airport. In part, the forecast indicated that after 0900 the surface wind would be from 070 degrees at 15 knots. Scattered clouds were forecast with bases at 2,000 feet above ground level (agl), and a broken ceiling was forecast at 5,000 feet agl. Expect temporary conditions of 2 miles visibility with rain showers, few clouds at 1,000 feet, broken ceiling at 1,500 feet, and an overcast sky at 3,500 feet.

The airport is about 9 miles east-southeast of the accident site. In part, at 0925, Lihue reported its surface wind was from 060 degrees at 12 knots, 3 miles visibility, light rain and mist, few clouds at 900 feet, and an overcast ceiling at 2,100 feet agl.


The nearest navigational aid (VORTAC) to the accident site is located at the Lihue Airport. This navigational aid (referred to as "LIH (H) VORTAC" is approximately 9 nm and 112 degrees from the accident site.

This VORTAC facility is a ground-based transmitter that continuously broadcasts very high frequency omni directional azimuth and distance information. The operator reported that the accident helicopter was equipped with avionics equipment that was capable of receiving the VOR signal.

A review of FAA records was performed from the Honolulu Automated Flight Service Station (AFSS), including its Daily Record of Facility Operation, air traffic control tapes and associated transcripts, and personnel statements. All aids to navigation associated with the pilot's route of flight were listed as having been in normal operational status during his flight.


FAA Records.

According to the FAA, no communications with the accident helicopter were recorded after its departure from the Lihue Airport, and all communications were normal. The FAA did not receive any requests for assistance from the helicopter pilot.

Operator's Pilots.

The pilot flying the lead helicopter reported that when he was conducting his tour flight and was about 2 miles northwest of the Lihue Airport on approach for landing, he heard the accident pilot transmit "I can't see." At that time he believed the accident pilot was crossing the power lines in the vicinity of the Hanalei ridge (a few miles north of the Waialeale crater).


The accident site is located in deep foliage on the southern face of a mountain adjacent to the south side of the Waialeale Crater. The approximate elevation of the crash site is between 2,350 and 2,450 feet msl. The site is about 200 feet below the ridgeline, on upsloping terrain that recovery personnel estimated angled upward at different locations between 40 and 85 degrees. The approximate coordinates of the crash site are 22 degrees 03 minutes north latitude by 159 degrees 29 minutes west longitude.

Evidence of fragmented main rotor blade structure was found at the initial point of impact, which was at the top of the wreckage distribution path. Based upon the topography of the mountainside and damage to surrounding vegetation, the estimated impact heading was about 350 degrees, magnetic. This impact heading is within about 30 degrees of being perpendicular to the face of the mountain.

Components from the helicopter were observed over an approximate 100-foot-long path down sloping from the main rotor blade impact signatures. Directly beneath the rotor blade fragments, the two skids were found which had separated from their cross tube attachment assemblies. Beneath this wreckage, the vertical fin, tail rotor, tail boom, and the fuselage were found. The engine was located near the bottom of the wreckage distribution path. (See the Wreckage Diagram and photographs for additional details.)

A Hawaiian Sectional Aeronautical Chart, 58th edition, was found in the wreckage. The chart had an effective date of May 21, 1998. The chart bore the statement "This chart will become obsolete for use in navigation . . . on November 5, 1998."

A maintenance record form was also found in the wreckage. No discrepancies or remarks were noted on the document. The Hobbs meter dispatch time was recorded on the form at 1,260.6 hours.


About June 27, 1998, an autopsy on the pilot was performed by the Medical Examiner, County of Kauai, at the Wilcox Memorial Hospital, 3420 Kuhio Highway, Lihue, Hawaii 96766.

The FAA's Civil Aeromedical Institute (CAMI), Toxicology and Accident Research Laboratory, performed toxicology tests on specimens from the pilot. No evidence of ethanol or any screened drugs was found.


Airframe Examination.

The airframe and the cabin interior were found fragmented and destroyed. The fuselage structure was observed crushed in an upward and aft direction. The cabin seats were similarly deformed.

Multiple fractures were present in the impact-damaged flight controls and related systems. Rotational score marks and lacerations were observed on the inside of the tail rotor drive shaft cover.

The main rotor blades were fragmented. The flexible coupling at the main gearbox was found torsionally deformed in the direction of rotation. The engine to tail rotor drive shaft flexible coupling was observed similarly twisted. The right horizontal stabilizer was intact; the left was crushed. The vertical stabilizer was intact.

The attitude indicator was not found. The turn coordinator was located and its rotor was examined. Circumferential score marks were present on the rotor. The helicopter's clock was found stopped, and it was indicating 9:31:35. See the aircraft manufacturer participant's report for additional details.

Engine and Component Examination.

The engine was initially examined on scene, and then a teardown examination was performed at the manufacturer's Grand Prairie, Texas, facility. The engine was found impact damaged. During the external examination, fuel was observed in the fuel filter, the inlet of the fuel injection manifold, and the outlet of the fuel control unit. The exhaust tail pipe was observed bent (rather than cracked).

In summary

NTSB Probable Cause

The pilot's decision to continue VFR flight into deteriorating weather conditions consisting of lowering ceilings and visibility in mountainous terrain, which resulted in the inadvertent entry into instrument meteorological conditions and a collision with a mountain side. A factor in the accident was the failure of the chief pilot, who had directly observed the deteriorating weather conditions, to direct the following pilots to avoid the area.

© 2009-2020 Lee C. Baker / Crosswind Software, LLC. For informational purposes only.