NTSB CAROL · Event
Event CEN21FA300
Registry · N302Z
FAA Aircraft Registry record.
Make / Model
BEECH 35-33
Year of manufacture
1960 · 61 years old at event
Engine
CONT MOTOR I0-470 SERIES (260 hp)
Seats / Engines
4 seats · 1 engine
Last airworthiness date
19600713
ADS-B equipped
Yes — Mode-S A328FF
Registrant of record
SUTHERLAND DERRICK L
Source: FAA Aircraft Registry (releasable master file).
Aircraft involved
Probable cause & findings
The pilot’s loss of airplane control due to spatial disorientation during low-level nighttime flight.
Factual narrative
HISTORY OF FLIGHTOn July 2, 2021, about 0225 central daylight time, a Beech 35-33 airplane, N302Z, was destroyed when it was involved in an accident near Roff, Oklahoma. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The Federal Aviation Administration’s (FAA) ADS-B data showed that the airplane made two flights on the day before the accident. The first flight departed from Ada Regional Airport (ADH), Ada, Oklahoma, about 2015; the airplane climbed to 3,000 ft and slowly descended until arriving at Ardmore Municipal Airport (ADM), Ardmore, Oklahoma, about 2035. The second flight departed from ADM about 2200 and flew toward ADH. The airplane made several circles southwest of ADH and then returned to ADM, landing there about 2253. During a postaccident interview, the pilot’s wife stated that her husband decided to return to ADM after observing a “big” cloud over ADH. She also stated that, according to her husband, instrument flight rules (IFR) flight conditions existed at the time and that he was not going to fly in those conditions. About 0211 on the day of the accident, the airplane again departed from ADM and was en route to ADH. Shortly before takeoff, the pilot had informed his wife that the weather would be visual flight rules along the entire route. According to ADS-B data, during the initial portion of the flight, the airplane’s altitude varied between 1,000 and 2,000 ft mean sea level (msl). (All altitudes are expressed as msl unless noted otherwise.) The pilot subsequently climbed the airplane to 3,000 ft before descending back to an altitude between 1,400 and 1,500 ft about 4.5 minutes before the accident occurred. The pilot continued to fly the airplane at that altitude (which was 200 to 300 ft above ground level) for about the next 2 minutes. The airplane’s groundspeed during the flight fluctuated between 70 and 139 knots with most of the flight conducted at a groundspeed of about 87 knots. Toward the end of the flight, the airplane made a left turn during which the airplane climbed to an altitude of about 1,600 ft at a rate of about 2,000 feet per minute. Subsequently, the airplane began descending at a rate that exceeded 2,700 feet per minute. The last ADS-B return showed that the airplane was about 0.2 miles west of the last radar return, about 280 ft above ground level, and along a track of 190°. The airplane’s last recorded groundspeed was 89 knots. The airplane impacted trees on a remote ranch about 14 nautical miles southwest of ADH. The figure below shows the airplane’s flight track (based on ADS-B data) during the accident flight. Figure. Accident airplane flight track. The ranch owner stated that heard a loud noise about the time of the accident and went outside but did not observe anything abnormal. He noted that the weather conditions were “very foggy and misty with low visibility.” PERSONNEL INFORMATIONThe pilot did not have an instrument rating. The pilot’s wife stated that he was an “excellent” pilot and did “quite a bit” of night flying. She also stated that he was used to flying in the dark. METEOROLOGICAL INFORMATIONThe National Weather Service (NWS) Weather Forecast Office (WFO) in Norman, Oklahoma, issued the following information in the Area Forecast Discussion at 1743 on the day before the accident: “mostly MVFR [marginal visual flight rules] conditions will persist through the period, with some chance at IFR cigs [ceilings] as storms move through.” The information also stated that scattered showers and thunderstorms would move out of northern and central Oklahoma by midday on the day of the accident. AIRMET Sierra was issued at 2145 on the day before the accident and was valid for the accident site at the accident time. The AIRMET was issued for IFR conditions and identified ceilings below 1,000 ft, visibility below 3 statute miles, precipitation, and mist. A Graphical Forecast for Aviation forecast imagery depicting IFR conditions was issued about 2300 on the day before the accident and was valid for 0100 on the day of the accident. This forecast imagery depicted surface visibilities as 1 to 3 statute miles, 3 to 5 statute miles, and greater than 5 statute miles at or near the accident location with scattered thunderstorms near the accident site. A graphical AIRMET for IFR conditions was depicted at the accident location. According to his wife, the pilot used Foreflight for weather information. The available evidence for this investigation did not indicate whether the pilot reviewed weather information before or during the accident flight. WRECKAGE AND IMPACT INFORMATIONThe debris field was about 210 ft in length along a heading of about 110°. The first identified piece of wreckage in the debris field was the left wingtip, which was followed by the left aileron; a small portion of the left-wing leading edge; the pitot tube, which was found on a large narrow ground scar in the dirt; and the right wing, which had separated from the fuselage at the wing root. The right wing came to rest with its leading edge down and the root of the wing wrapped around a tree, which was bent in the direction of the debris path. The main wreckage was located about 12 ft beyond the right wing and consisted of the cabin, aft fuselage, and inboard left wing. The engine was located about 6 ft beyond the main wreckage. The engine had separated from the firewall (which exhibited crush damage) and engine mounts and came to rest on its left side against two trees. The left side of the engine exhibited more impact damage than the right side. Postaccident examination revealed no evidence of a pre-existing mechanical malfunction or failure that would have precluded normal operation of the airplane. ADDITIONAL INFORMATIONSpatial Disorientation The FAA Civil Aeromedical Institute’s publication titled “Introduction to Aviation Physiology” defines spatial disorientation as a “loss of proper bearings; state of mental confusion as to position, location, or movement relative to the position of the earth.” Factors contributing to spatial disorientation include changes in acceleration, flight in IFR conditions, frequent transfer between visual flight rules and IFR conditions, and unperceived changes in aircraft attitude. The FAA’s Airplane Flying Handbook (FAA-H-8083-3C) describes hazards associated with flying when the ground or horizon is obscured. The handbook states, in part, the following: The vestibular sense (motion sensing by the inner ear) can and will confuse the pilot…false sensations are often generated, leading the pilot to believe the attitude of the airplane has changed when, in fact, it has not. These false sensations result in the pilot experiencing spatial disorientation. As a result, the pilot “needs to believe what the flight instruments show about the airplane’s attitude regardless of what the natural senses tell.” The pilot was conducting a personal flight at night in low-visibility conditions. According to automatic dependent surveillance-broadcast (ADS-B) data, during the initial portion of the flight, the airplane’s altitude was generally between 1,000 and 2,000 ft before the airplane climbed to 3,000 ft. About 4.5 minutes before the accident, the airplane entered a gradual descent to an altitude between about 1,400 and 1,500 ft and continued to fly at that altitude (200 to 300 ft above ground level) for about the next 2 minutes. The airplane then entered a left turn that became increasingly tighter. During this turn, the airplane climbed to about 1,600 ft before descending. The last ADS-B return showed that the airplane was about 0.2 miles west of the last radar return, about 280 ft above ground level, and along a track of about 190°. Postaccident examination revealed no evidence of a pre-existing mechanical malfunction or failure that would have precluded normal operation of the airplane. The pilot was not instrument rated. The available evidence for this accident did not indicate whether the pilot received weather information for the route of flight. The pilot likely anticipated visual meteorological conditions given that, shortly before takeoff, he informed his wife that the airplane would be in those conditions along the entire route. The low-visibility night conditions were conducive to the development of spatial disorientation. Although ADS-B data showed that the airplane was flying close to terrain during the final portion of the flight, the airplane was maneuvering over an area without much cultural lighting (such as the illumination from the reflection of lighting in a metropolitan area). Without such lighting, the pilot would not have had reliable visual references for maintaining attitude control. The spiral flightpath was consistent with the pilot experiencing the known effects of spatial disorientation. Also, the wreckage distribution and extensive airplane fragmentation were consistent with a highenergy impact resulting from the effects of spatial disorientation. 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).
- — Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot
- — Personnel issues-Psychological-Perception/orientation/illusion-Spatial disorientation-Pilot
- — Environmental issues-Conditions/weather/phenomena-Ceiling/visibility/precip-Low visibility-Effect on personnel
Verbatim from NTSB's published report. Source file
NTSB_2021_CEN21FA300.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 (spatial disorientation, thunderstorm). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- Embry-Riddle Scholarly Commons 2025 · Journal article (IJAAA)
Design, Implementation, and Testing of Spatial Disorientation Scenarios in a Modified Hexapod Motion Simulator
Abstract Investigations into aviation accidents aim to identify root causes and enhance safety. Despite advancements in safety measures, technology, and education, general aviation accident rates rema…
- Embry-Riddle Scholarly Commons 2024 · Journal article (IJAAA)
The Impact of Thunderstorms on Take-off Data in South Africa
Aviation and meteorology are entwined disciplines, as aviation occurs in the atmosphere. Prevailing weather conditions at take-off are of utmost importance to aviation.
- AOPA Air Safety Institute 2022 · Safety advisor
Safety Advisor: Spatial Disorientation
Safety advisor on the perceptual illusions that cause spatial disorientation: the leans, graveyard spiral, somatogravic and somatogyral illusions, false horizon, and Coriolis.
- NASA NTRS 2019 · Conference Paper
Evaluation of Low Cost, User-Centered Alerting Devices for the Mitigation of Flight Crew Spatial Disorientation
The National Aeronautics and Space Administration (NASA) is conducting research into technologies which have the potential to reduce flight crew Spatial Disorientation (SD).
- NASA NTRS 2019 · Presentation
Pre-Flight Training of Autonomic Responses for Mitigating the Effects of Spatial Disorientation During Spaceflight
The National Aeronautics and Space Administration (NASA) has identified a potential risk of spatial disorientation, motion sickness, and degraded performance to astronauts during re-entry and landing …
- NASA NTRS 2019 · Other
The Role of Spatial Disorientation in Fatal General Aviation Accidents
In-flight Spatial Disorientation (SD) in pilots is a serious threat to aviation safety. Indeed, SD may play a much larger role in aviation accidents than the approximate 6-8% reported by the National …
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