# NTSB CEN26LA233: Burkhart Grob Flugzeugbau G103 Twin Astir, N4101M, Gregory, MI, June 3, 2026

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 4 · Limited · Final report
- Date: June 3, 2026, 16:00 local (20:00 UTC)
- Place: Gregory, MI
- Coordinates: 44.442083, -84.064361
- Nearby events: https://openairdocs.org/map.md?lat=44.4421&lon=-84.0644&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing: Dragged wing/rotor/float/other](https://openairdocs.org/ntsb-events/093)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report September 11, 2026
- Report: Approved by Office Director
- Investigation class: Class 4 - Basic report with no Prelim publish
- NTSB office: Central Region
- Parties: FAA
- NTSB case key (mKey): 203229
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN26LA233
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/203229/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=203229
- Page: https://openairdocs.org/ntsb/CEN26LA233

## Probable cause

The flight instructor’s improper planning during the simulated aborted launch which resulted in a touchdown on unsuitable terrain.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Communication (personnel): issuing instructions](https://openairdocs.org/ntsb-findings/02063538): Personnel issues › Task performance · Instructor/check pilot (probable cause); cases with it: [Burkhart Grob Flugzeugbau G103 TWIN ASTIR, 1 case](https://openairdocs.org/ntsb-findings/02063538/cases.md?model=1660202), [All aircraft, 26 cases](https://openairdocs.org/ntsb-findings/02063538/cases.md)
- [Aircraft](https://openairdocs.org/ntsb-findings/01060000): Aircraft › Aircraft oper/perf/capability · Incorrect use/operation (probable cause); cases with it: [Burkhart Grob Flugzeugbau G103 TWIN ASTIR, 1 case](https://openairdocs.org/ntsb-findings/01060000/cases.md?model=1660202), [All aircraft, 63 cases](https://openairdocs.org/ntsb-findings/01060000/cases.md)
- [Terrain: sloped/uneven terrain](https://openairdocs.org/ntsb-findings/03021017): Environmental issues › Physical environment · Awareness of condition (probable cause); cases with it: [Burkhart Grob Flugzeugbau G103 TWIN ASTIR, 1 case](https://openairdocs.org/ntsb-findings/03021017/cases.md?model=1660202), [All aircraft, 270 cases](https://openairdocs.org/ntsb-findings/03021017/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Initial climb: Simulated/training event](https://openairdocs.org/ntsb-events/600); cases with it: [Burkhart Grob Flugzeugbau G103 TWIN ASTIR, 1 case](https://openairdocs.org/ntsb-events/600/sequence.md?model=1660202), [All aircraft, 173 cases](https://openairdocs.org/ntsb-events/600/sequence.md)
- [Landing: Dragged wing/rotor/float/other](https://openairdocs.org/ntsb-events/093) (defining event); cases with it: [Burkhart Grob Flugzeugbau G103 TWIN ASTIR, 1 case](https://openairdocs.org/ntsb-events/093/sequence.md?model=1660202), [All aircraft, 319 cases](https://openairdocs.org/ntsb-events/093/sequence.md)

## Analysis

The flight instructor reported that while practicing an immediate landing after liftoff, with the student pilot at the flight controls, the glider landed past the end of the runway in tall grass on a downward sloping hill. The left wing lowered and the glider pivoted and came to rest in a muddy area. The rudder sustained substantial damage during the landing. The flight instructor reported that there were no preaccident mechanical malfunctions or failures with the glider that would have precluded normal operation. The flight instructor remarked that in the future he would plan to terminate the tow earlier so there would be sufficient runway remaining to land on and brief whether the terrain beyond the runway was suitable for landings.

## Aircraft

- Registration: [N4101M](https://openairdocs.org/aircraft/N4101M), registered now, S/N 3796, built 1983 (OpenAirDocs)
- Reported make and model: BURKHART GROB FLUGZEUGBAU G103 TWIN ASTIR
- Registry model: [Burkhart Grob Flugzeugbau G103 TWIN ASTIR](https://openairdocs.org/model/burkhart-grob-flugzeugbau-g103-twin-astir) (registry code 1660202) (OpenAirDocs)
- Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs)
- Category: Glider
- Serial number: 3796
- Year built: 1983
- Airframe hours: 4764.9
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Sandhill Soaring Club Inc.
- Registered owner: Sandhill Soaring Club Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Unknown, November 15, 2025
- Departed: 69G, Gregory, MI
- Airport: 69G, Richmond Field Airport, runway 18, 2,471 × 100 ft, grass/turf
- Equipment: Unknown

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 71; injuries: none; flight engineer, flight instructor, airline transport; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; seat: rear; restraint: 4-point; flight hours: 24,908 total, 14,806 as pilot in command, 24 in the last 90 days, 1 in the last 30 days, 1.3 in the last 24 hours
- Student pilot; age 70; injuries: none; student; seat: front; restraint: 4-point; flight hours: 52.5 total, 28.3 in this make and model, 8.9 as pilot in command, 5.1 in the last 90 days, 0.9 in the last 30 days, 0.4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 240° at 4 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point 52 °F
- Altimeter: 30.01 inHg
- Observed at: KHTL, 27 nm away
- METAR: METAR KHTL 031953Z AUTO 24004KT 10SM CLR 26/11 A3001 RMK AO2 SLP159 T02560111=

## 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 20260603005999A](https://openairdocs.org/incident/20260603005999A), Jun 3, 2026: Grob 103, Gregory, MI, Substantial damage. The flight was a glider instructional flight, where a student was receiving instruction to prepare for a practical test. The instructor wanted to simulate a…

## Other investigations on N4101M (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 CHI93LA230](https://openairdocs.org/ntsb/CHI93LA230), Jun 26, 1993: Burkhart Grob G103 (N4101M), Ionia, MI, substantial damage. Probable cause: THE PILOT IN COMMAND'S FAILURE TO MAINTAIN THE PROPER GLIDEPATH.

## Docket (2 files)

The files NTSB released with the investigation on September 11, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=203229. 11.3 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 10.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20829130&FileExtension=pdf&FileName=CEN26LA233%20-%206120_Redacted-Rel.pdf
- Photos (item 2, PDF, 4 pages, 3 photos, 446 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20829315&FileExtension=pdf&FileName=CEN26LA233%20-%20PHOTOS-Rel.pdf

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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