# NTSB FTW94LA250: Let L-23, N923SB, Stillwater, OK, July 24, 1994

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 24, 1994, 10:00 local (15:00 UTC)
- Place: Stillwater, OK
- Coordinates: 36.080711, -97.070602 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=36.0807&lon=-97.0706&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report September 24, 1995
- Report: Approved by Office Director
- NTSB case key (mKey): 19123
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW94LA250
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/19123/pdf
- Page: https://openairdocs.org/ntsb/FTW94LA250

## Probable cause

THE CERTIFIED FLIGHT INSTRUCTOR'S FAILURE TO MAINTAIN FLYING SPEED.

## Sequence of events

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

- Loss of control - in flight, takeoff - initial climb
  - airspeed(vs) - not maintained, pilot in command(cfi) (cause)
  - stall - inadvertent, pilot in command(cfi)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

DURING AN INSTRUCTIONAL FLIGHT, A GLIDER WAS BEING TOWED BY A CAR AS PART OF THE STUDENT PILOT'S QUALIFICATION.  AFTER SEPARATION FROM THE TOWING VEHICLE, THE INSTRUCTOR PILOT NOTICED THAT THE GLIDER WAS NOT GAINING AIRSPEED.  THE AIRCRAFT THEN STALLED AND STRUCK THE GROUND.

## Factual narrative

On July 24, 1994, approximately 1000 central daylight time, a Let L-23 glider, N923SB, was substantially damaged during take- off.  The instructor pilot and his student were not injured.  Visual meteorological conditions prevailed for the 14 CFR 91 flight.

During an interview conducted by a Federal Aviation Administration inspector, the instructor pilot reported that the glider was being towed by car for takeoff as part of a student qualification.  After separation from the towing vehicle the instructor pilot felt that they were not gaining airspeed and stalled.  The glider struck the ground resulting in structural damage.

## Aircraft

- Registration: [N923SB](https://openairdocs.org/deregistered/N923SB-2006-08-16), registration cancelled 2006-08-16, S/N 917923, built 1992 (OpenAirDocs)
- Reported make and model: LET L-23
- Registry model: [Let L-23 SUPER BLANIK](https://openairdocs.org/model/let-l-23-super-blanik) (registry code 1360308) (OpenAirDocs)
- Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs)
- Category: Glider, amateur-built
- Serial number: 917923
- Engines: unknown
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Registered owner: Cimmaron Soaring

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, unknown; flight hours: 11,200 total

## Weather

- Conditions: Visual (VMC), Day
- Wind: 220° at 9 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 91 °F, dew point 64 °F
- Altimeter: 30.00 inHg
- Observed at: OKC, 30 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 19940724019249A](https://openairdocs.org/incident/19940724019249A), Jul 24, 1994: Let L23, Stillwater, OK, Substantial damage. Stalled after auto tow release.

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.