# NTSB LAX93FA086: Rockwell 690B, N300CP, Herlong, CA, December 31, 1992

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: December 31, 1992, 15:36 local (23:36 UTC)
- Place: Herlong, CA
- Coordinates: 40.139774, -120.159881 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.1398&lon=-120.1599&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed, report October 8, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27817
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX93FA086
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27817/pdf
- Page: https://openairdocs.org/ntsb/LAX93FA086

## Probable cause

AN INADVERTENT ENCOUNTER WITH SEVERE TURBULENCE WHICH EXCEEDED THE DESIGN STRENGTH OF THE AIRPLANE'S STRUCTURE.

## Sequence of events

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

- In flight encounter with weather, descent
  - preflight briefing service - not used, pilot in command
  - weather forecast - inaccurate, nws personnel
  - weather condition - mountain wave (cause)
  - weather condition - turbulence (cause)
- Airframe/component/system failure/malfunction, descent
  - design stress limits of aircraft - exceeded (cause)
  - horizontal stabilizer attachment - overload
  - horizontal stabilizer attachment - failure,total
  - vertical stabilizer attachment - overload
  - vertical stabilizer attachment - failure,total
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE PILOT AND FLIGHT NURSE WERE EN ROUTE TO PICK UP A MEDICAL PATIENT. THE AIRPLANE EXPERIENCED AN IN-FLIGHT BREAKUP WHILE FLYING BY THE LEEWARD SIDE OF THE SIERRA NEVADA MOUNTAINS IN THE GENERAL AREA WHERE STANDING LENTICULAR CLOUDS HAD BEEN OBSERVED. NO EVIDENCE WAS FOUND THAT THE PILOT OBTAINED A WEATHER BRIEFING FROM FLIGHT SERVICE OR THE DUAT VENDORS PRIOR TO DEPARTURE. PILOTS FLYING IN THE GENERAL AREA HAD REPORTED AIRSPEED VARIANCES FROM PLUS 60 TO MINUS 40 KTS. AN IN-FLIGHT WEATHER ADVISORY FOR OCCASIONAL MODERATE TURBULENCE WAS IN EFFECT. ABOUT ONE HOUR AFTER THE ACCIDENT THE WEATHER SERVICE ISSUED A SIGMET FOR SEVERE TURBULENCE.

## Aircraft

- Registration: [N300CP](https://openairdocs.org/deregistered/N300CP-1996-04-11), registration cancelled 1996-04-11, S/N 11374 (OpenAirDocs)
- Reported make and model: Rockwell 690B
- Registry model: [Rockwell International 690B](https://openairdocs.org/model/rockwell-international-690b) (registry code 7630516) (OpenAirDocs)
- Category: Airplane
- Serial number: 11374
- Airframe hours: 4052
- Engines: GARRETT 331-5-251K 717 horsepower turbo prop
- Damage: Destroyed
- Flight: Part 91
- Operator: Medic Air, Inc.
- Registered owner: Brs Services, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, December 12, 1992
- Departed: RNO, RENO, NV
- Destination: SVE, SUSANVILLE, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 51; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 6,984 total, 782 in this make and model, 87 in the last 90 days, 28 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day

## 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 19921231052539A](https://openairdocs.org/incident/19921231052539A), Dec 31, 1992: Gulstm 690B, Herlong, CA, Destroyed, 2 fatal. During high speed descent in severe turbulence updraft loading bent a wing and separated empannege. Emsa ferry.

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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