# NTSB LAX92LA005: Robinson R22B, N900AB, Honolulu, HI, October 4, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: October 3, 1991, 14:45 local (Oct 4, 1991, 00:45 UTC)
- Place: Honolulu, HI
- Location: 21.3069° N, 157.8583° W: Placed by OpenAirDocs: center of Honolulu, HI, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=21.3069&lon=-157.8583&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report December 4, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 27467
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX92LA005
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27467/pdf
- Page: https://openairdocs.org/ntsb/LAX92LA005

## Probable cause

THE IMPROPER USE OF THE FLIGHT CONTROLS BY THE INSTRUCTOR PILOT ND THE FAILURE TO MAINTAIN PROPER ROTOR RPM.

## Sequence of events

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

- Loss of engine power(partial) - nonmechanical, maneuvering - turn to reverse direction
  - collective - improper use of, pilot in command(cfi) (cause)
  - rotor rpm - not maintained, pilot in command(cfi) (cause)
- In flight collision with terrain/water, descent - uncontrolled
  - descent - not corrected, pilot in command(cfi)
  - remedial action - inadequate, pilot in command(cfi)

## Analysis

ACCORDING TO STATEMENTS FROM BOTH THE INSTRUCTOR AND STUDENT, THE FLIGHT WAS PRACTICING PINNACLE APPROACHES IN A MOUNTAINOUS AREA.  THE INSTRUCTOR SAID HE PERFORMED A HIGH RECONNAISSANCE OF THE SPOT, AND THEN THE FLIGHT ENCOUNTERED A DOWN DRAFT DURING THE FINAL APPROACH TO THE PEAK.  THE INSTRUCTOR SAID HE PERFORMED A RIGHT PEDDLE TURN TO FLY DOWN THE SLOPE OVER A STREAM.  THE LOW ROTOR HORN CAME ON AND THE INSTRUCTOR SAID HE ATTEMPTED TO GET THE ROTOR RPM BACK INTO THE GREEN ARC BUT BEFORE HIS CONTROL INPUTS WERE EFFECTIVE THE MAIN ROTOR BLADE COLLIDED WITH TREES ON THE STREAM BANK AND THE HELICOPTER CRASHED INTO THE WATER.

## Aircraft

- Registration: [N900AB](https://openairdocs.org/deregistered/N900AB-1999-02-24), registration cancelled 1999-02-24, S/N 1455 (OpenAirDocs)
- Reported make and model: ROBINSON R22B
- Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1455
- Engines: LYCOMING O-320 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Makani Helicopters, Inc.
- Registered owner: North County Helicopters
- Airworthiness certificate: Standard, Normal
- Last inspection: Unknown, January 2, 2000
- Airport: 0

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 25; commercial, flight instructor; medical: class 2, valid medical--no waivers/lim.; flight hours: 1,725 total, 1,200 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 80° at 10 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 84 °F

## 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 19911003045099A](https://openairdocs.org/incident/19911003045099A), Oct 3, 1991: Robsin R22BETA, Honolulu, HI, Substantial damage. Trying to recover from downdraft while attempting a pinnacle landing in mountain terrain,rotors struck a tree.

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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