Premium research interface

The modern interface for aviation safety intelligence.

Search investigations, review source evidence, monitor watched reports, and trace long-term patterns from one calm, data-first workspace.

63k+
Reports indexed
1940-2026
Coverage
Recent
Last data refresh
Featured Report

Loading…

Loading featured report…

Loading…
Open Report

Safety trends by operating rule

Track fatal and non-fatal accident patterns across Part 91, Part 135, and Part 121 operations.

Loading trend charts…

Browse the aviation graph

Move quickly by aircraft, airport, operator, and time with indexes built for research, not wandering.

Last Data Update

By Decade

By Month

Aircraft Manufacturer

More manufacturers

Airports

More airports

Operators

More operators

About

Aviation safety reports, made easier to study

NTSB Reports is an independent research and search tool for public aviation accident and incident records. It brings NTSB aviation reports, structured fields, docket files, extracted figures, photos, videos, and update history into one searchable interface.

The goal is practical safety education: make it faster to find relevant investigations, compare similar events, review factual records, and understand the evidence behind probable-cause and preliminary reports.

The investigative work and source records belong to the National Transportation Safety Board and the published investigation record. This site is not affiliated with or endorsed by the NTSB.

FAQs

NTSB Report

September 7, 2009 · Robinson Helicopter R44 II · N4186Y

Central, AK

Overview

Report Status
Final with probable cause
Event Type
Accident
Date
September 7, 2009
Injury Outcomes
No injuries (3 uninjured)
Location
Central, AK
Aircraft
Robinson Helicopter R44 II
Tail Number
N4186Y
Operator
Alpine Air Alaska
Injuries
None
Aircraft Damage
Substantial
NTSB Number
ANC09LA098

The airline transport helicopter pilot reported that he was on a Title 14, CFR Part 135 passenger flight and was approaching a mountain ridge to drop off two technicians at a radio repeater site. Before beginning his approach, the pilot circled the site to determine the wind conditions, and then began his approach into a 10 knot wind. During the approach to the 5,657 foot level site, the pilot said he encountered a downdraft as the helicopter approached the site, and the helicopter descended below his anticipated approach path. He initiated a go-around, but the helicopter continued to descend, and 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, sustaining substantial damage to the right side of the tail boom. The pilot reported wind conditions on the ground as variable, gusting between 10 and 20 knots. In the pilot’s written statement to the NTSB, he reported that there were no preaccident mechanical problems with the helicopter.

NTSB Probable Cause

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.

Full Narrative

On September 6, 2009, about 1735 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, Alaska. 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 1400, 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 preaccident 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.

Flight

Event TypeAccident
Event Time17:35 AKDT
Nearest Airport0nm
Flight Plan FiledCvfr
Flight Plan ActivatedYes
Aircraft FireNo
Aircraft ExplosionNo

Aircraft

AircraftRobinson Helicopter R44 II
Tail NumberN4186Y
Aircraft CategoryHeli
DamageSubstantial
OperatorAlpine Air Alaska
Operating RulePart 135
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · IO-540-AE1A5 · Reciprocating · 260
Seats4

People & Injuries

Injury SummaryNo injuries (3 uninjured)
Fatal0
Serious0
Minor0
Uninjured3
Total3
Crew 1Age 40 · First Class · None

Conditions

ConditionsVMC
LightDaylight
Wind10 kt, gusting 20 kt
Visibility20 sm
CeilingBroken clouds 2000 ft
Temperature / Dew Point41 C / 0 C
Altimeter29.60 inHg
Weather SourcePILO

Appendix: Source Data