# NTSB LAX92LA012: Beech K35, N9559R, Grass Valley, CA, October 11, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: October 11, 1991, 16:00 local (23:00 UTC)
- Place: Grass Valley, CA
- Coordinates: 39.18011, -120.979484 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.1801&lon=-120.9795&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report January 22, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27475
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX92LA012
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27475/pdf
- Page: https://openairdocs.org/ntsb/LAX92LA012

## Probable cause

THE INADVERTENT ENCOUNTER WITH A MICROBURST/DOWNBURST PHENOMENA ASSOCIATED WITH THUNDERSTORM ACTIVITY.  A FACTOR IN THE ACCIDENT WAS THE FAILURE OF THE PILOT TO ADEQUATELY ASSESS THE WEATHER CONDITIONS DURING THE LANDING ATTEMPT.

## Sequence of events

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

- Loss of control - in flight, approach - vfr pattern - final approach
  - weather condition - microburst/dry (cause)
  - weather condition - turbulence (cause)
  - weather condition - windshear (cause)
  - weather evaluation - inaccurate, pilot in command (contributing factor)
  - in-flight planning/decision - poor, pilot in command
  - aircraft control - not maintained, pilot in command
- In flight collision with terrain/water, go-around (vfr)
  - remedial action - not possible, pilot in command

## Analysis

IN AN ORAL STATEMENT, THE PILOT SAID THAT AS HE APPROACHED THE AIRPORT HE OBSERVED SQUALL LINE ACTIVITY AND DECIDED TO ORBIT UNTIL THE WEATHER CLEARED.  AFTER THE WEATHER CONDITIONS VISUALLY IMPROVED, THE PILOT ENTERED THE PATTERN FOR LANDING.  HE STATED THAT ON SHORT FINAL APPROACH THE AIRCRAFT ENCOUNTERED SEVERE TURBULENCE AND A DOWN DRAFT.  THE PILOT INITIATED A GO AROUND, HOWEVER, THE AIRCRAFT ROLLED VIOLENTLY AND THE WING TIP STRUCK THE GROUND.  AN AIRPORT ATTENDANT STATED THAT HE WAS IN THE OFFICE WHERE THE WEATHER OBSERVATION INSTRUMENTS ARE LOCATED AT THE TIME OF THE ACCIDENT.  HE SAID THAT THE WINDS WERE 30 TO 40 KNOTS WITH SUDDEN 180 DEGREE CHANGES IN DIRECTION AT THE TIME THE PILOT ATTEMPTED HIS APPROACH.  THUNDERSTORM CLOUDS WERE VISIBLE IN THE DISTANCE AND THE AIRPORT WAS EXPERIENCING INTERMITTENT HEAVY RAIN SHOWERS.

## Aircraft

- Registration: [N9559R](https://openairdocs.org/deregistered/N9559R-1994-08-08), registration cancelled 1994-08-08, S/N D6125 (OpenAirDocs)
- Reported make and model: BEECH K35
- Registry model: [Beech K35](https://openairdocs.org/model/beech-k35) (registry code 1151524) (OpenAirDocs)
- Category: Airplane
- Serial number: D6125
- Airframe hours: 2380
- Engines: CONTINENTAL IO-470C 250 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Mike Collishaw
- Registered owner: Mike Collishaw
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, November 3, 1990, 57 hours before
- Departed: RHV, SAN JOSE, CA
- Airport: 017, Nevada County, runway 7, 3,920 × 50 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 32; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 316 total, 57 in this make and model, 228 as pilot in command, 25 in the last 90 days, 13 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: variable at 15 knots, gusting 40
- Visibility: 50 statute miles
- Lowest ceiling: 4,000 ft overcast

## 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 19911011045969A](https://openairdocs.org/incident/19911011045969A), Oct 11, 1991: Beech K35, Grass Valley, CA, Substantial damage. Tried to land in excessive turbulence from a squall line nearby. Wing tip struck ground and aircraft cartwheeled.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.