ASN Wikibase Occurrence # 217377
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| Date: | Sunday 6 September 2009 |
| Time: | 17:35 |
| Type: |  Robinson R44 Raven II |
| Owner/operator: | Alpine Air Alaska, Inc. |
| Registration: | N4186Y |
| MSN: | 12533 |
| Year of manufacture: | 2008 |
| Total airframe hrs: | 487 hours |
| Engine model: | Lycoming IO-540-AE1A5 |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Location: | about 38 miles SE of Central, Yukon-Koyukuk Census Area, Alaska -
 United States of America
|
| Phase: | Landing |
| Nature: | Passenger - Non-Scheduled/charter/Air Taxi |
| Departure airport: | Fairbanks International Airport, Fairbanks, Alaska (FAI/PAFA) |
| Central, Yukon-Koyukuk Census Area, Alaska | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
On September 6, 2009, about 17:35 ADT (Alaska Daylight Time), a Robinson R44 II helicopter, N4186Y, sustained substantial damage during a hard landing while on approach to a mountain ridge, about 38 miles southeast of Central, Yukon-Koyukuk Census Area, Alaska. (At approximate coordinates 65'57.3889"N, 144'78.0833"W)
The helicopter was being operated by Alpine Air Alaska, Inc., Girdwood, Alaska, as a visual flight rules (VFR) on-demand charter flight, under the provisions of Title 14 Code of Federal Regulations (CFR) Part 135. The airline transport pilot and the two passengers were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight departed the Fairbanks International Airport, Fairbanks, Alaska, about 14:00 ADT, en route to various communication sites near Central.
During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on September 15, the pilot reported that the purpose of the flight was to transport two maintenance technicians to various mountaintop radio repeater sites in the area. He said that before beginning his approach to the 5,657 feet msl site, he circled the area to determine the wind conditions, and then planned his approach into a 10 knot headwind. During the approach to the treeless, tundra and rock-covered site, the pilot said he encountered a strong downdraft, and the helicopter began to descend below his anticipated approach path. He initiated a go-around, but the helicopter continued to descend, and it landed hard, about 150 feet short and down slope of his intended touchdown point. During touchdown, the toes of the helicopter’s skids broke, and the helicopter rocked forward and aft. The helicopter sustained substantial damage to the right side of the tail boom.
The pilot characterized wind conditions on the ground as variable, gusting between 10 and 20 knots.
In the pilot’s written statement to the NTSB he indicated that there were no pre accident mechanical problems with the helicopter. Additionally, he recommended relocating the landing site to an area above the ridge to minimize the exposure to downdrafts, and to install a functioning windsock.
During a telephone conversation with the NTSB IIC on April 2, 2010, a representative from Alpine Air reported that the owner of the remote radio repeater site recently installed a new windsock, and is considering relocating the existing landing site.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot’s failure to maintain control of the helicopter after an in-flight encounter with a downdraft while landing. Contributing to the accident was the pilot’s inadequate evaluation of wind conditions. Robinson R44 N4186Y was repaired and returned to service, and has been sold on twice since the bove accident, both times two owners in Alaska.
Accident investigation:
 |
|
Sources:
NTSB
2. FAA Registration: https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?omni=Home-N-Number&nNumberTxt=N4186Y
3. http://helihub.com/2009/09/07/7-sep-09-n4186y-robinson-r44-central-us-alaska/
4. https://uk.flightaware.com/resources/registration/N4186Y
5. http://www.griffin-helicopters.co.uk/accidentdetails.aspx?accidentkey=50576
6. http://www.aviationdb.com/Aviation/Aircraft/4/N4186Y.shtm
7. https://planecrashmap.com/list/ak/
8. https://en.wikipedia.org/wiki/Central,_Alaska
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 07-Nov-2018 18:34 | Dr.John Smith | Added |
| 07-Nov-2018 18:35 | Dr.John Smith | Updated [Narrative] |
Corrections or additions? ... Edit this accident description
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