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LAX91LA163 · Schempp-Hirth VENTUS B/16.6 VENTUS B/1

7 Apr 1991 · LAKE COBB, CA, United States

Schempp-Hirth VENTUS B/16.6 VENTUS B/1 · Accident: in flight encounter with weather while maneuvering

From Vacaville, CA to an unrecorded destination

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Event

NTSB case
LAX91LA163
Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
Accident
InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
Completed
API-reported fatalities
0 · all aircraft and ground
Ground fatalities
0
OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
General aviation
WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
Visual Meteorological Cond

Schempp-Hirth VENTUS B/16.6 VENTUS B/1

Category
Glider
RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
N81PT
Onboard fatalities
Unknown
Route
From Vacaville, CATo not recorded
Aircraft age
Not recorded
Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
Part 91: General Aviation
Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
Maneuvering
First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
In flight encounter with weather
Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
Wire, transmission
DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
Substantial

Cause areas

  • Pilot in command › Visual lookout, improper

Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.

NTSB narrative

AFTER THE AERO TOW RELEASED THE PILOT SOARED TO MT. ST. HELENA AND THEN ONTO COBB MOUNTAIN WHERE THERMAL LIFT WAS REPORTED. UPON ARRIVING OVER COBB MOUNTAIN HE DID NOT ENCOUNTER ANY THERMAL LIFT. REALIZING A FORCED LANDING WAS IMMINENT THE PILOT SELECTED A OFF-FIELD LANDING AREA WHICH WAS SURROUNDED ON THREE SIDES. THE PILOT REPORTED THAT THE NORTHWEST SIDE OF THE FIELD WAS UNOBSTRUCTED EXCEPT FOR A SMALL WIRE FENCE WHICH POSED NO PROBLEM FOR THE OFF-FIELD LANDING. THE PILOT FAILED TO SEE A SMALL TRANSMISSION WIRE WHICH CROSSED THE FINAL APPROACH COURSE ABOUT 25 FEET ABOVE GROUND LEVEL. THE GLIDER STRUCK THE WIRE WHICH CAUSED THE GLIDER TO NOSE DOWN ABOUT 40 DEGREES AND STRIKE THE GROUND IN A WINGS LEVEL ATTITUDE.

Probable cause

THAT THE PILOT'S VISUAL LOOKOUT WAS IMPROPER. CONTRIBUTING TO THIS ACCIDENT WAS THE UNMARKED TRANSMISSION WIRE.

Verbatim NTSB analysis and probable cause from the NTSB dataset

Sources

NTSB record LAX91LA163
Event ID
20001212X16805
Case number
LAX91LA163
Dataset
historical-pre2008
Source SHA-256
89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
  • Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
  • Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
  • The date is the local date, which is the same as the UTC date the NTSB stores.
  • API snapshot SHA-256: a9e443d3838fbfb3801a952f38af1976267c0c58265ec2d33a7aa74585e0e5be; retrieved 2026-09-21T23:37:23.125Z.