# NTSB CHI95LA308: Let L-23 Super Blanik, N99970, White Bear Lake, MN, September 5, 1995

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 5, 1995, 16:45 local (21:45 UTC)
- Place: White Bear Lake, MN
- Coordinates: 45.090324, -93.01062 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=45.0903&lon=-93.0106&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report April 1, 1996
- Report: Approved by Office Director
- NTSB case key (mKey): 10020
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI95LA308
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10020/pdf
- Page: https://openairdocs.org/ntsb/CHI95LA308

## Probable cause

the pilot's delayed retraction of the spoilers.  Factors were the excessive sink rate and the power lines.

## Sequence of events

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

- In flight collision with object, approach - vfr pattern - final approach
  - object - wire,static (contributing factor)
  - proper descent rate - not maintained, pilot in command (contributing factor)
  - spoiler retraction - delayed, pilot in command (cause)

## Analysis

The pilot reported that he was on final approach when he experienced 'quick' and 'unexpected' altitude loss.  The landing gear impacted a power line.  The wire broke but the glider descended onto a road.  No evidence of preimpact malfunction was discovered.  The pilot wrote 'I question whether I actually retracted the spoilers.  This may account for the excess loss of altitude.'

## Factual narrative

On September 5, 1995, at 1645 central daylight time, a Let L-23 Super Blanik, N99970, operated by the Redwing Soaring Association, sustained substantial damage when it impacted power lines during final approach in White Bear Lake, Minnesota.  The private pilot reported no injuries.  The local, personal flight was conducted under 14 CFR Part 91 in visual meteorological conditions.  No flight plan was filed.

The pilot reported that he was on final approach and extended the spoilers to reduce his altitude.  He thought he retracted the spoilers.  He experienced "quick" and "unexpected" altitude loss.  The landing gear impacted a power line.  The wire broke but the glider descended onto a road.  He wrote "I question whether I actually retracted the spoilers.  This may account for the excess loss of altitude."

According to a Federal Aviation Administration (FAA) inspector, who examined the wreckage,  no evidence of preimpact malfunction was discovered.

## Aircraft

- Registration: [N99970](https://openairdocs.org/deregistered/N99970-2001-05-09), registration cancelled 2001-05-09, S/N 026012 (OpenAirDocs)
- Reported make and model: LET L-23 SUPER BLANIK (L-23 SUPER)
- Registry model: [Let BLANIK L-13](https://openairdocs.org/model/let-blanik-l-13) (registry code 1360306) (OpenAirDocs)
- Category: Glider
- Serial number: 026012
- Engines: unknown
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Redwing Soaring Association
- Airworthiness certificate: Standard, Normal

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 72; private; seat: front; flight hours: 83 total, 25 in this make and model, 48 as pilot in command, 2 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 240° at 5 knots, gusting 3
- Lowest ceiling: none
- Temperature: 81 °F

## Other investigations on N99970 (1)

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.

- [NTSB LAX76DUJ14](https://openairdocs.org/ntsb/LAX76DUJ14), Aug 7, 1975: Blanik L-13 (N99970), Carefree, AZ, substantial damage

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.