NTSB CAROL · Event
Event CEN12LA490
Aircraft involved
Probable cause & findings
The glider pilot’s failure to maintain sufficient altitude and airspeed while turning to the base leg of the traffic pattern, which resulted in a stall/spin and impact with trees and terrain.
Factual narrative
On July 29, 2012, at 1343 eastern daylight time, an experimental Smith Applebay Zuni II glider, N1ZV, sustained substantial damage when it impacted trees and terrain while on the downwind leg to runway 36 at the Richmond Field Airport (69G), Gregory, Michigan. The pilot, the sole occupant, received serious injuries. The glider was registered to and operated by the pilot under the provisions of the 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed for the local flight which originated from 69G at 1329. The pilot reported that he completed the pre-takeoff checklist, which included a positive control check of the flight controls. He reported that the takeoff and tow to 3,000 feet above ground level (agl) was normal. The pilot released the glider from the tow airplane at 3,000 feet agl about 2 miles northwest of 69G. The pilot was unable to find the necessary lift, and as the glider lost altitude, he started flying back toward the airport. Still not finding the needed lift, he proceeded toward the initial point for landing on runway 36. As the pilot flew the downwind pattern leg, he realized that he was not going to be able to complete the pattern. He attempted to clear the tree line that crossed the downwind leg, but the glider hit the trees and subsequently impacted the terrain. A witness located at the airport reported that he observed the glider on the downwind leg. He reported that the glider's altitude was low – about 125 to 150 feet agl, and it was in close to the airport and flying "somewhat slowly." The glider seemed to slow down even more as it began to turn to the base leg. He reported that the left wing stalled and the glider pitched down nearly vertical. It completed about 1/2 spin before it disappeared behind the trees about 2,000 feet away. Another witness at the airport also reported that the glider was too low on the downwind leg. He reported that the glider went down as it turned to shorten the pattern. A Federal Aviation Administration inspector examined the glider wreckage. Flight control cable continuity was confirmed from the flight controls to their respective attach points on the flight control surfaces. The inspection of the glider did not reveal any evidence of pre-impact failure or malfunction. The pilot reported that the takeoff and tow to 3,000 feet above ground level (agl) was normal. The pilot released the glider from the tow airplane about 2 miles northwest of the airport. He was unable to achieve the necessary lift, and, as the glider lost altitude, he started flying back toward the airport and proceeded toward the initial point for landing on the runway. As the pilot flew the glider on the downwind pattern leg, he realized that he was not going to be able to complete the traffic pattern. He attempted to clear the tree line that crossed the downwind leg, but the glider hit the trees and subsequently impacted terrain. A witness reported that the glider's altitude was about 125 to 150 feet agl when it was on the downwind leg and that its airspeed was too low. The witness added that the glider continued to slow as it turned to the base leg, at which point, the left wing stalled, and then the glider pitched down nearly vertical and completed about 1/2 spin before it disappeared behind the trees. A postaccident examination of the airframe revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).
- C Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Altitude-Not attained/maintained - C
- C Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Airspeed-Not attained/maintained - C
- C Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C
Verbatim from NTSB's published report. Source file
NTSB_2012_CEN12LA490.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (stall). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- NASA NTRS 2026 · Conference Paper
Computational Analysis of Steady State Aerodynamics of Transonic Truss-Braced Wing Configuration in Deep Stall
This study presents a computational investigation of steady state aerodynamics of the Subsonic Ultra-Green Aircraft Research (SUGAR) Transonic Truss-Braced Wing (TTBW) configuration over a wide range …
- arXiv 2023 · arXiv preprint
Automating Bird Diverter Installation through Multi-Aerial Robots and Signal Temporal Logic Specifications
This paper tackles the task assignment and trajectory generation problem for bird diverter installation using a fleet of multi-rotors.
- arXiv 2023 · arXiv preprint
Variation of Critical Crystallization Pressure for the Formation of Square Ice in Graphene Nanocapillaries
Two-dimensional square ice in graphene nanocapillaries at room temperature is a fascinating phenomenon and has been confirmed experimentally.
- arXiv 2023 · arXiv preprint
Polycrystallinity enhances stress build-up around ice
Damage caused by freezing wet, porous materials is a widespread problem, but is hard to predict or control. Here, we show that polycrystallinity makes a great difference to the stress build-up process…
- arXiv 2022 · arXiv preprint
Enhanced Prediction of Three-dimensional Finite Iced Wing Separated Flow Near Stall
Icing on three-dimensional wings causes severe flow separation near stall. Standard improved delayed detached eddy simulation (IDDES) is unable to correctly predict the separating reattaching flow due…
- Embry-Riddle Scholarly Commons 2021 · Journal article (JAAER)
Analysis on the Negative Emotional, Physiological, and Cognitive Responses Elicited from of the Activation of a Stall Alarm
Failing to identify an aerodynamic stall can lead to the inability of an aircraft to sustain flight. To warn pilots of an impending or fully-developed stall, many aircraft have safety devices installe…
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