# NTSB LAX83LA234: Let L-13, N99965, California City, CA, April 2, 1983

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 2, 1983, 10:15 local (18:15 UTC)
- Place: California City, CA
- Coordinates: 35.150852, -117.919273 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.1509&lon=-117.9193&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 23715
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX83LA234
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/23715/pdf
- Page: https://openairdocs.org/ntsb/LAX83LA234

## Sequence of events

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

- In flight encounter with weather, maneuvering
  - planning/decision - improper, pilot in command (cause)
  - weather condition - mountain wave (contributing factor)
  - weather condition - turbulence (contributing factor)
- Airframe/component/system failure/malfunction, maneuvering
  - design stress limits of aircraft - exceeded, pilot in command (cause)
  - horizontal stabilizer surface - bent (contributing factor)
  - vertical stabilizer surface - bent (contributing factor)
  - fuselage,skin - buckled (contributing factor)

## Analysis

DURING FLT, THE GLIDER SUSTAINED IN-FLT STRUCTURAL DAMAGE WHILE MANEUVERING AT AN ALTITUDE OF APRX 17,500 FT MSL IN THE VICINITY OF CALIFORNIA CITY, CA. DURING A PRELIMINARY VERBAL STATEMENT TO AN FAA INSPECTOR, THE PLT STATED THAT HE HAD DONE A COUPLE OF LOOPS. HE SAID HE HAD JUST RECOVERED TO LEVEL FLT WHEN HE HEARD A COUPLE OF LOUD BANGS, THEN FELT A SEVERE VIBRATION IN THE CONTROLS. LATER, THE PLT INSISTED THAT NO AEROBATIC MANEUVERS WERE PERFORMED, BUT THAT HE HAD ENCOUNTER TURBULENCE & HAD 'FLOWN THRU A ROTOR.' WRINKLES WERE FOUND IN THE SKIN ON THE AFT FUSELAGE & EMPENNAGE, THE VERTICLE STABILIZER WAS DEFORMED & THE LEFT HORIZONAL STABILIZER & ELEVATOR HAD SEVERAL AREAS OF DEFORMATION. SURFACE WINDS IN THE AREA WERE FROM 270 DEG AT 22 GUSTING 28 KTS. PEAK SURFACE WINDS WERE FROM 290 DEG AT 42 KTS. STANDING LENTICULAR CLOUDS WERE REPORTED TOPPING THE MOUNTAINS & SIGMET JULIET 4 WAS IN EFFECT CAUTIONING OCCASIONAL SEVERE TURBULENCE BELOW 16,000 FT MSL.

## Aircraft

- Registration: [N99965](https://openairdocs.org/deregistered/N99965-2023-01-16), registration cancelled 2023-01-16, S/N 025918, built 1974 (OpenAirDocs)
- Reported make and model: LET L-13
- Registry model: [Let BLANIK L-13](https://openairdocs.org/model/let-blanik-l-13) (registry code 1360306) (OpenAirDocs)
- Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs)
- Category: Glider
- Serial number: 025918
- Airframe hours: 613
- Engines: unknown
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Aquarian Soaring
- Registered owner: William A. Koml
- Airworthiness certificate: Standard, Aerobatic
- Last inspection: Annual, July 25, 1982, 58 hours before
- Departed: L71, CALIFORNIA CITY, CA
- Airport: L71, California City Muni

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; commercial; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 5,000 total, 100 in this make and model, 4,800 as pilot in command, 15 in the last 90 days, 10 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 22 knots, gusting 28
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 61 °F, dew point 43 °F
- Altimeter: 30.00 inHg
- Observed at: WJF, 18 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 19830402021219A](https://openairdocs.org/incident/19830402021219A), Apr 2, 1983: Let L13BLANIK, California City, CA, Substantial damage. Reported severe turbulence. Found skin wrinkled and horizontal stabilizer deformed. Passenger reported acrobatics.

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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