CEN23LA254

NTSB accident investigation · Let L-23 Super Blanik · Gregory, MI · June 21, 2023

Accident · Serious injuriesClass 3 · LimitedFinal report
Date
June 21, 2023, 15:30 local (19:30 UTC)
Place
Gregory, MI
Injuries
1 serious, 1 minor
Damage
Substantial damage
Phase of flight
Approach
Aircraft
N10BRLet L-23 Super Blanik
Defining event
Approach-VFR pattern final: Aerodynamic stall/spin
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 3
NTSB office
Central Region
Parties
FAA - East Michigan
FAA report
20230621008479A
Case key
192425

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

On this page

Probable cause

The flight instructor’s failure to maintain adequate airspeed and his exceedance of the glider’s critical angle of attack, leading to an aerodynamic stall during the off-field landing.

Findings · 2

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Performance/control parameters: angle of attackAircraft › Aircraft oper/perf/capability · Capability exceededLet L-23 SUPER BLANIK: 5 casesAll aircraft: 990 casesProbable cause
Use of equip/info: aircraft controlPersonnel issues › Task performance · Instructor/check pilotLet L-23 SUPER BLANIK: 10 casesAll aircraft: 9,295 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The student pilot reported that he was flying the glider until about 10 minutes before the accident, when the flight instructor took over control and started looking for thermals to gain altitude. He said the flight instructor was mostly quiet until he said they were going to perform an off-field landing. The glider flew across a tree line about 150 ft above ground level and turned to land in a bean field. Neither the student nor the flight instructor had any recollection of the accident. Postaccident examination showed that the forward fuselage was crushed upward, and rearward and the outboard 6 ft of the left wing was separated. The separation point had signatures indicating upward bending of the tip. The damage to the glider was consistent with a nose-low, left-wing-low impact. Flight control continuity was verified from the cockpit to all control surfaces. No anomalies were detected. Based on the available information, the glider likely had insufficient altitude to return to the departure airstrip and the flight instructor attempted an off-field landing. The nose-low, left-wing-low impact suggested that the instructor likely exceeded the glider’s critical angle of attack and encountered an aerodynamic stall at low altitude during the landing attempt.

Factual narrative

On June 21, 2023, about 1530 eastern daylight time, a Let L-23 Super Blanik, N10BR, was substantially damaged when it was involved in an accident near Richmond Field Airport (69G), Gregory, Michigan. The flight instructor was seriously injured, and the student pilot received minor injuries. The glider was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The glider came to rest about 3,500 ft northwest of the north end of the runway at 69G. The student pilot reported that he was flying the glider until about 10 minutes before the accident when the flight instructor took over control and started looking for thermals to gain altitude. He said the flight instructor was mostly quiet until he said they were going to perform an off-field landing. The glider flew across a tree line about 150 ft above ground level and turned to land in a bean field. The student had no further recollection of the accident. The flight instructor also reported that he had no recollection of the flight. The glider sustained substantial damage to the fuselage and both wings. Postaccident examination showed that the forward fuselage was crushed upward, and rearward and the outboard 6 ft of the left wing was separated. The separation point had signatures indicating upward bending of the tip. The damage to the glider was consistent with a nose-low, left-wing -ow impact. Flight control continuity was verified from the cockpit to all control surfaces. No preimpact anomalies were detected.

Aircraft

Registration
N10BR
Reported as
Let L-23 Super Blanik
Category
Glider
Serial number
917826
Built
1991
Damage
Substantial damage
Flight
Instructional · Part 91
Operator
Sandhill Soaring Club Inc
Registered owner
Sandhill Soaring Club Inc
Airworthiness certificate
Standard, Utility
Last inspection
Annual · May 5, 2023
Airport
69G
Equipment
Unknown

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew · 2

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
68
Injuries
Serious
Certificates
Airline transport, Commercial, Flight instructor
Airplane ratings
Single-engine sea, Single-engine land, Multi-engine land
Instrument ratings
Airplane
Medical
Class 2, With waivers/limitations
Seat
Rear
Restraint
4-point
Flight hours
24,700 total · 130 in this make and model
Role
Student pilot
Age
15
Injuries
Minor
Seat
Front
Restraint
4-point
Flight hours
4 total · 3 in this make and model

Weather

Conditions
Visual (VMC) · Day
Wind
100° at 9 knots
Visibility
10 statute miles
Temperature
84 °F, dew point 55 °F
Altimeter
30.13 inHg
Observed at
KOZW, 12 nm away
METAR
METAR KOZW 211935Z AUTO 10009KT 10SM SCT060 SCT080 29/13 A3013 RMK AO2 T02910127=

Docket · 5

The files NTSB released with the investigation on November 21, 2024, on NTSB’s docket system: statements, records, photos and specialists’ reports. 5.0 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.