# NTSB LAX91LA414: Let L-13, N86661, Adelanto, CA, September 29, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 29, 1991, 13:40 local (20:40 UTC)
- Place: Adelanto, CA
- Coordinates: 34.659194, -117.509162 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=34.6592&lon=-117.5092&mi=10
- Phase of flight: [Emergency descent](https://openairdocs.org/ntsb-phases/600) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report December 15, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 27376
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA414
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27376/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA414

## Probable cause

IMPROPER PLANNING/DECISION BY THE PILOT.  LOSS OF THERMAL LIFT WAS A RELATED FACTOR.

## Sequence of events

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

- Forced landing, descent - emergency
  - weather condition - no thermal lift (contributing factor)
- On ground/water encounter with terrain/water, landing - roll
  - planning/decision - improper, pilot in command (cause)
  - terrain condition - high vegetation
  - terrain condition - rough/uneven

## Analysis

THE CERTIFICATED PRIVATE PILOT AND A PASSENGER WERE ON A LOCAL AREA GLIDER FLIGHT AFTER BEING LAUNCHED BY AERIAL TOW AIRPLANE.  WHILE RETURNING TO THE PRIVATE AIRSTRIP, THE PILOT WAS UNABLE TO MAINTAIN THERMAL LIFT AND DECIDED TO MAKE A LANDING ON A DIRT ROAD.  DURING THE LANDING ROLL, THE RIGHT WINGSTRIP STRUCK HIGH VEGETATION, CAUSING THE GLIDER TO PIVOT TO THE RIGHT INTO UNEVEN TERRAIN.  THE RIGHT WING AND EMPENNAGE WERE DAMAGED.

## Aircraft

- Registration: N86661 (not matched to a registry record)
- Reported make and model: LET L-13
- Category: Glider
- Serial number: 25423
- Airframe hours: 1230
- Engines: unknown
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Big Wing Flyers Inc.
- Registered owner: Big Wing Flyers Inc.
- Airworthiness certificate: Standard, Aerobatic
- Last inspection: Annual, May 18, 1991, 57 hours before
- Departed: NONE, ADELANTO, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--no waivers/lim.; seat: rear; flight hours: 2,268 total, 90 in this make and model, 2,065 as pilot in command, 24 in the last 90 days, 7 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 90° at 7 knots
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 90 °F

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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