# NTSB ATL99TA126: Hughes OH-6A, N584SD, Hernando, MS, September 7, 1999

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: September 7, 1999, 11:30 local (16:30 UTC)
- Place: Hernando, MS
- Coordinates: 34.820335, -89.979438 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=34.8203&lon=-89.9794&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report June 23, 2000
- Report: Approved by Office Director
- NTSB case key (mKey): 47294
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL99TA126
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47294/pdf
- Page: https://openairdocs.org/ntsb/ATL99TA126

## Probable cause

The in-flight encounter with weather that resulted in the loss of tail rotor control.  The pilot failed to maintain directional control and the helicopter collided with the ground.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight encounter with weather, approach - vfr pattern - final approach
  - weather condition - dust devil/whirlwind (cause)
- Loss of control - in flight, landing - flare/touchdown
  - directional control - not maintained, pilot in command
- In flight collision with terrain/water, landing

## Analysis

The pilot, a volunteer with the sheriff's department, was conducting proficiency training when the accident occurred. According to the pilot, he had completed three approaches and was on the fourth approach when he encountered a dust devil along the approach path. After encountering the dust devil, when several feet above the ground, the helicopter yawed to the right. In an effort to recover from the yawed condition, the pilot instantly rolled off the throttle control, and the helicopter collided with the ground. No mechanical problems were reported with the helicopter by the pilot. The post-accident examination of the helicopter also did not disclose any mechanical problem.

## Factual narrative

On September 7, 1999, at 1130 central daylight time, a Hughes OH6A, N584SD, collided with the ground while on approach to a helipad in Hernando, Mississippi. The helicopter was operated by the Desoto County Sheriff's  Department  under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The helicopter sustained substantial damage. The private pilot was not injured. The public use flight departed Hernando, Mississippi, at 1110.

The pilot, a volunteer with the sheriff's department, was conducting  proficiency training when the accident occurred. According to the pilot, he had completed three approaches and was on the fourth approach when he encountered a dust devil along the approach path. After encountering the dust devil, several feet above the ground, the pilot reported that the helicopter yawed to the right. In an effort to recover from the yaw condition, the pilot instantly rolled off the throttle control, and the helicopter collided with the ground.

No mechanical problems were reported with the helicopter by the pilot. The post-accident examination of the helicopter also failed to disclose a mechanical problem.

## Aircraft

- Registration: N584SD (not matched to a registry record)
- Reported make and model: Hughes OH-6A
- Category: Helicopter
- Serial number: 67-16449
- Airframe hours: 2914
- Engines: Allison 250-C-20 278 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Registered owner: Desota County Sheriff Dept
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, November 24, 1998
- Airport: NONE, Desoto County Helipad

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 53; private; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 523 total, 523 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 90 °F, dew point 63 °F
- Altimeter: 29.00 inHg
- Observed at: MEM, 30 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19990907026959A](https://openairdocs.org/incident/19990907026959A), Sep 7, 1999: Hughes OH6A, Hrnando, MS, Substantial damage. (.19) On September 7, 1999, at 1130 central daylight time, a Hughes OH6A, N584SD, collided with the ground while on approach to a helipad in hernhando,…

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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