Eurocopter AS-350-BA accident near Mt. Waialeale, Hawaii, June 25, 1998
On June 25, 1998 at about 7:32 pm local time, a Eurocopter AS-350-BA (helicopter), registered N594BK, was destroyed in an accident near Mt. Waialeale, Hawaii. It was a flight of an unrecorded kind under charter and air-taxi rules (Part 135). 6 people were killed. The weather was instrument conditions (cloud, fog or low visibility).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 25, 1998 · about 7:32 pm local time
- Place
- Mt. Waialeale, Hawaii · map
- Type
- Accident
- Injuries
- 6 people were killed.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft
- Eurocopter AS-350-BA · all AS-350-BAs on the register
- Registration
- N594BK · no longer on the register · serial 2735
- Damage
- Destroyed
- Flight
- Flight of an unrecorded kind · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
While operating under visual flight rules on an on-demand for hire aerial sight seeing tour, the helicopter encountered instrument meteorological conditions and impacted the 80-degree upsloping face of a mountain, 200 feet below its ridge crest. The tour was to circumnavigate a mountainous area on the island, with a visit to an extinct volcanic crater in a mountain valley. Three helicopters departed on the tour, with about 2 minutes between each departure. The pilot, who was employed by the operator 2.5-months earlier, was in trail behind the company's most experienced (chief) pilot, and second most experienced pilot. None had received a weather briefing from an FAA approved source as required in the company operations specifications. Throughout the flight they were in radio contact with each other. The two lead pilots were a few minutes ahead of the accident pilot as he approached an area of the valley near the crater where inclement weather existed. The second pilot ahead of the accident helicopter said that when he exited the crater near the accident site, he encountered heavy rain showers and lowering ceilings and visibilities. Although the accident pilot attempted to follow the company pilots ahead of him, he did not observe the valley entrance to the Waialeale crater viewpoint and flew past it. As the flight progressed, the pilot encountered lowering ceilings, heavy intensity rain showers, and reduced flight visibility. The pilot became disoriented, misjudged his location, and while cruising toward what he believed was the prescribed crater entranceway inadvertently entered instrument meteorological conditions. Just before the collision, the pilot transmitted to the pilots ahead of him that the weather was getting worse and that he could not see. The second pilot then provided a suggested heading that would take the accident pilot away from the mountainous terrain. The helicopter impacted the mountain on a heading nearly opposite of the one suggested. The helicopter was subsequently recovered and examined. No evidence of any preimpact mechanical malfunction was noted. 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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: instrument: helicopter; rotorcraft: helicopter
- Flight time: 3,170 hours in all; 220 in this make and model; 220 in the last 90 days; 63 in the last 30 days; 1,900 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 6,875 hours
- Last inspection: 100-hour inspection, June 18, 1998; 35 hours since
- Maximum gross weight: 4,630 lb
- Seats: 7
- Landing gear: fixed
- Engine: Turbomeca ARRIEL 1B (turboshaft); 0 hours total
The flight
- Departed from: LIH Lihue HI at 6:43 pm
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 060° at 12 knots
- Visibility: 3 statute miles
- Sky: overcast at 2,100 ft; scat at 900 ft
- Temperature: 70°F (21°C), dew point 68°F (20°C)
- Altimeter: 30.00 inHg
- Observation at 7:25 pm from LIH, 9 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 5 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.