CEN20LA169
2020-05-03 · Delta, Colorado, United States · Fatal · 1 aircraft · Status: Completed
Airport AJZ
Aircraft involved
Probable cause & findings
The pilot’s exceedance of the airplane’s critical angle of attack during a test flight which resulted in an aerodynamic stall and impact with terrain.
Factual narrative
HISTORY OF FLIGHTOn May 3, 2020, at 1110 mountain daylight time, a Rans S-12 airplane, N427LB, was destroyed when it was involved in an accident near Delta, Colorado. The pilot sustained fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight. A witness stated that he talked to the pilot about the airplane’s stability issues, and the pilot told him that he performed some high-speed taxi tests and was trying to adjust to correct the issues. The witness did not think the pilot was going to fly [on the day of the accident] and was only going to perform another set of high-speed taxi tests. The witness believed the pilot was caught off guard and the airplane became airborne. A witness at Blake Field Airport (AJZ), Delta, Colorado, stated that he saw the airplane takeoff from runway 14, and it appeared to be under control. The airplane flew along the left downwind leg for runway 21 about 300-400 ft above ground level, in straight, level, and stable flight. After the airplane passed the approach end of runway 32, it pitched down, banked sharply right, and the engine throttled back. The witness said it was hard to tell if the engine was throttled back before the sudden change in pitch or in its response to the change in pitch; a loss of control/stall occurred. Another witness at AJZ stated that he heard an engine repetitively going from full engine power, then back off, and then return to full engine power. He said that when he saw the airplane, he thought the wings were rocking. The airplane banked to the right, was very low, and pitched "a lot." About 3–4 seconds later, the airplane impacted the ground. AIRCRAFT INFORMATIONThe airplane owner stated the pilot was restoring the airplane since its purchase in June 2018. The owner said that he talked to the pilot on the day before the accident, and the pilot told him that he was close to having the airplane flyable. The owner asked the pilot to call him if he was going to fly the airplane so that he could watch the flight, but the pilot did not contact him. Airplane records did not contain weight and balance information and such information was not received by the National Transportation Safety Board Investigator-in-Charge. AIRPORT INFORMATIONThe airplane owner stated the pilot was restoring the airplane since its purchase in June 2018. The owner said that he talked to the pilot on the day before the accident, and the pilot told him that he was close to having the airplane flyable. The owner asked the pilot to call him if he was going to fly the airplane so that he could watch the flight, but the pilot did not contact him. Airplane records did not contain weight and balance information and such information was not received by the National Transportation Safety Board Investigator-in-Charge. WRECKAGE AND IMPACT INFORMATIONThe accident site was about 220 feet from the approach end of runway 32 in an upright position. The wings and empennage with attached control surfaces were intact with the fuselage. The wing flaps were retracted. The airplane wings and fuselage sustained structural damage to both wings and fuselage. Postaccident examination of the airplane confirmed flight control continuity from the control surfaces to the cockpit flight controls. The horizontal stabilizer’s angle of incidence was positioned, attached, and secured to the lowest bolt hole along the leading-edge root of the vertical stabilizer. Three bags containing shot (each weighing about 24.4 lbs, 25.2 lbs, and 25.2 lbs respectively) and a fourth shot bag that was ruptured and estimated to be about the same weight as the other three, were found in the passenger seat area. One of two dumbbell weights (marked 35 lbs) was also found in the passenger seat area. Recovery personnel recovered the other dumbbell weight from an unknown location in the airplane. The pilot of the test flight was attempting to correct airplane stability issues before the flight. A witness assumed that the pilot was planning to perform a high-speed taxi test rather than flight, and that the airplane’s takeoff was unintentional. After takeoff, the airplane was seen in the airport traffic pattern at 300-400 ft above ground level. Witnesses then observed the airplane change pitch and bank while the engine was heard increasing to full power and then decreasing. The airplane stalled, impacted terrain, and was destroyed by impact forces. Post-accident examination of the airplane confirmed flight control and engine continuity. There were four ballast bags (about 25 lbs each) and two dumbbell weights (marked 35 lbs). All the ballast bags and one dumbbell weight were in the passenger seat area. High-speed taxi testing is not a test area of aircraft stability and control. Given the pilot’s previous statement of his intentions and the presence of ballast/weights in the passenger seat area, it is likely that he was experimenting with airplane stability and control when the airplane exceeded its critical angle of attack, which led to an aerodynamic stall. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
FAA avdata. C = Cause, F = Factor.
- — Aircraft-Aircraft oper/perf/capability-Performance/control parameters-(general)-Attain/maintain not possible
- — Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Angle of attack-Capability exceeded
- — Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot
Verbatim from NTSB's published report. Source file
NTSB_2020_CEN20LA169.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
Matched on aircraft type or causal vocabulary (stall, loss of control). All research papers
- Semantic Scholar 2016 · Article (Interacción) Trajectory Recovery System: Angle of Attack Guidance for Inflight Loss of Control
This paper describes the design and development of an ecological display to aid pilots in the recovery of an In-Flight Loss of Control event due to a Stall (ILOC-S).
- NTSB Aircraft Accident Reports 2010 · Accident report Loss of Control on Approach — Colgan Air Flight 3407
Colgan Air 3407 / Continental Connection (Q400) Buffalo NY, February 12, 2009 — 50 fatalities. Definitive investigation of the Colgan 3407 stall-stick-pusher crash on approach to Buffalo.
- 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 …
- Embry-Riddle Scholarly Commons 2025 · Journal article (JAAER) A Scoping Review of Aviation Loss of Control Inflight Research
Loss of control – inflight (LOC-I) contributes to aircraft accidents at unacceptably high rates. Significant industry efforts and research have aimed to improve LOC-I prevention, detection, and recove…
- SKYbrary (Eurocontrol) 2024 · SKYbrary article Loss of Control In-Flight (LOC-I) — SKYbrary Knowledge Base
SKYbrary comprehensive knowledge-base entry on Loss of Control In-Flight — definitions, contributing factors, accident case studies (Air France 447, Colgan 3407), and prevention strategies.
- Semantic Scholar 2024 · Article (International Conference on Networking and Services) Risk Assessment of Loss of Control In-Flight Trajectories for Urban Air Mobility Safety
In Urban Air Mobility (UAM), maintaining a minimum separation between aircraft is a safety requirement, which becomes challenging amidst congested air traffic and off-nominal conditions, such as Loss …