Eurocopter AS-350 BA accident near Chickaloon, Alaska, June 23, 2008
On June 23, 2008 at about 6:45 pm local time, a Eurocopter AS-350 BA (helicopter), registered N357CH, was substantially damaged in an accident during maneuvering (hover) near Chickaloon, Alaska. It was an external-load flight under external-load helicopter rules (Part 133). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's incorrect actions during an out-of ground-effect hover, which resulted in the helicopter entering a main rotor ring vortex state, and a settling with power condition, producing an excessive descent rate and collision with terrain.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 23, 2008 · about 6:45 pm local time
- Place
- Chickaloon, Alaska · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Eurocopter AS-350 BA · all AS-350 BAs on the register
- Registration
- N357CH · no longer on the register · serial 2658
- Damage
- Substantial damage
- Flight
- External-load flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
Prior to the accident flight, the pilot transported several students from the National Outdoor Leadership School and their equipment to a remote glacier camp at about 8,950 feet mean sea level (msl). During that flight, the main rotor rpm dropped enough to sound the low rotor speed warning horn for a few seconds. At a staging area, in preparation for the accident flight, the pilot prepared an external load of about 400 pounds of equipment in a net to be attached to the bottom of the helicopter by a 50-foot-long line. The pilot then lifted off into an out-of-ground-effect hover (HOGE) to assess the required power, and noted that he needed about 70 percent power to maintain a hover. He then flew to the top of the glacier with the external cargo net; upon arrival at the upper camp, he established a 75-foot hover while pulling maximum power. He then reduced power to lower the cargo net to the snow. The pilot said that he reduced power too much and that the helicopter began to descend rapidly. He said that he felt a small vibration, reminiscent of entering the vortex ring produced by the main rotors. The vibration then smoothed out, but the helicopter was descending quickly. The pilot applied power but did not release the external load. The helicopter collided with snow and rolled onto its right side. The helicopter's gross weight at the time of the accident, including the external load, fuel, and the weight of the pilot and passenger, was about 4,286 pounds. At that weight, the helicopter should have been capable of an HOGE of about 9,500 feet msl.
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
What happened, in order
- External load event (Rotorcraft) during maneuvering (hover)
- Settling with power/vortex ring state during maneuvering (hover) defining event
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
- Roll over during post (impact)
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Descent rate › Incorrect use/operation
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: helicopter; rotorcraft: helicopter
- Flight time: 1,100 in this make and model
- Last flight review: March 1, 2008
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Maximum gross weight: 4,630 lb
- Seats: 7
- Landing gear: fixed
- Engine: Arriel 1B (turboshaft); 0 hours total
- Operator: Last Frontier Air Ventures Ltd.
The flight
- Departed from: Sutton AK at 12:00 pm
- Destination: Chickaloon AK
- Flight plan: none
Weather at the time
- Light: daylight
- Sky: ovct at 9,000 ft
- Temperature: 25°F (-4°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
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.