CEN24FA188

The student pilot was conducting a local solo flight. Review of flight track data revealed that, during the final 6.5 minutes of the flight, the airplane completed several large deceleration-and-acceleration cycles between 1,000 and 1,700 ft above ground level (agl). During each of these cycles, the airplane’s airspeed decreased below aerodynamic stall speed before it increased again. The airspeed and altitude profiles during these maneuvers were consistent with the pilot practicing aerodynamic stalls. Shortly before the accident, the airplane entered a rapid climb while the airspeed decreased below aerodynamic stall speed, consistent with an intentional power-on stall entry. There was a 6-second interruption in track data coverage after the airplane entered the aerodynamic stall, but when coverage resumed, the airplane was in a rapid descent that continued until the end of recorded data about 8 seconds later. A witness reported seeing the airplane flying at slow speed, almost “hovering” in the air, before it suddenly entered a spiraling nosedive. The airplane completed at least 6 to 8 rotations in the descending spiral before it descended out of sight behind a hill. An extensive postimpact fire thermally damaged most of the airplane. A wreckage examination revealed no evidence of a preimpact mechanical malfunction or failure that would have prevented normal airplane operation. The pilot’s autopsy and postmortem toxicology tests did not reveal any evidence of medical incapacitation or impairment. Based on the available information, the pilot likely did not maintain airplane control during the intentional power-on stall, which resulted in an inadvertent spin at an altitude from which he was unable to recover.

Recent Maintenance According to maintenance documentation, the last annual inspection of the airplane was completed on July 25, 2023, at 3,025.8 total airframe hours and 1,959.0 hours since the last engine overhaul. A 50-hour inspection was completed on April 9, 2024, at 3,073.6 hours total airframe time. The last logged maintenance was to replace the right fuel sender unit gasket, which was also completed on April 9, 2024, at 3,075.8 hours total airframe time. A review of the airplane maintenance logbooks and a summary of recent pilot-reported discrepancies did not reveal any unresolved maintenance issues. According to the airplane operator’s dispatch system documentation, the airplane’s recording tachometer indicated 3,085.5 hours at the beginning of the accident flight. The airplane’s recording tachometer was destroyed by the postimpact fire, which prevented calculation of the airplane’s airframe and engine times at the time of the accident. Weight and Balance The airplane’s empty and maximum takeoff weights were 1,135.5 lbs and 1,600 lbs, respectively. The airplane’s useful load was 464.5 lbs. The gross weight and center-of-gravity location at engine startup were calculated based on the reported pilot weight of 155 lbs, estimated 10 lbs of baggage, a full fuel load of 22.5 gallons (135 lbs), and 6 quarts of engine oil (11 lbs). The gross weight at engine startup was 1,446.5 lbs. center-of-gravity location was 34.6 inches aft datum, and the moment was 50,100 lbs-inches. Based on the Cessna 150L Owner’s Manual, the airplane was within weight-and-balance limits at engine startup and at the time of the accident. Aerodynamic Stall Speed According to the Cessna 150L Owner’s Manual, the wings-level aerodynamic stall speed at maximum gross weight (1,600 lbs) with the flaps retracted (0°) is 55 mph. The aerodynamic stall speed decreases to 48 mph with the flaps fully extended (40°). The wings-level aerodynamic stall speed is reduced by the square root of the weight ratio when the airplane is operated at a weight less than the maximum gross weight. On May 15, 2024, about 2039 central daylight time, a Cessna 150L airplane, N1701Q, was destroyed during an accident near Godley, Texas. The student pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 solo instructional flight. According to available ADS-B track data, at 1948:44, the airplane was in a climb after takeoff from runway 15 at Cleburne Regional Airport (CPT), Cleburne, Texas. The airplane entered a right traffic pattern for runway 15, completed one landing, and then flew south-southeast of CPT, as shown in figure 1. At 1959:10, the airplane turned west and flew over Lake Pat Cleburne before it turned south-southwest. Between 2001:55 and 2004:40, about 5 nautical miles (nm) south-southwest of CPT, the airplane completed a series of left and right 360° turns between 3,200 and 3,300 ft mean sea level (msl) before it continued south-southwest. At2007:30, the airplane turned west-northwest and continued climbing to a maximum altitude of about 4,100 ft msl. At 2011:40, the airplane entered a descent from 4,100 ft msl while it continued west-northwest. At 2014:04, the airplane leveled off at 3,300 ft msl. At 2015:01, the airplane entered a climb while it continued west-northwest. At 2017:00, the airplane turned west as it climbed to about 4,000 ft msl. Between 2018:25 and 2022:15, about 4 nm south-southeast of Granbury, Texas, the airplane completed a series of descending left and right turns. After the turns, the airplane continued to descend as it flew east-northeast toward the Brazos River near DeCordova, Texas. Figure 1. Plot of airplane flight track data. Between 2025:50 and 2028:56, about 1.25 nm south-southwest of DeCordova, Texas, the airplane completed a series of descending left-and-right turns over the Brazos River near the west side of Lake Granbury. During the turns, the airplane descended to about 2,300 ft msl before it entered a climb. After the turns, the airplane continued east over Lake Granbury and climbed to about 2,600 ft msl. After it flew over the eastern side of Lake Granbury, the airplane continued east-southeast back toward CPT. During the final 10 minutes of the flight, there were two prolonged periods without recorded FAA ADS-B track data. However, an internet-based flight tracking website, FlightAware.com, continued to track the airplane without similar data dropouts and was used as the primary source of track information for the remainder of the flight. Airplane performance calculations based on the available track data revealed that, between 2033:15 and 2038:00, the airplane completed four large deceleration-and-acceleration cycles, as shown in figure 2. During each of these four cycles, the airplane’s calibrated airspeed (CAS) decreased below aerodynamic stall speed before it increased again. The airspeed and altitude profiles during these maneuvers were consistent with the pilot practicing aerodynamic stalls. At 2037:30, during the fourth deceleration-and-acceleration cycle, the airplane decelerated to about 31 mph CAS before it began accelerating. Over the next 10 seconds, the airplane briefly leveled off at 1,865 ft msl before it entered a climb. At 2038:25, the airplane had accelerated to 91 mph CAS and was climbing through 1,940 ft msl at a vertical speed about 100 ft per minute (fpm). Between 2038:25 and 2039:20, the airplane began decelerating as the vertical speed increased from 100 fpm to 800 fpm before returning to near zero. Between 2039:21 and 2039:26, the airplane’s vertical speed increased from near zero to about 1,085 fpm. Between 2039:26 and 2039:30, the airplane transitioned from a climb to a descent as it decelerated to about 33 mph CAS. At 2039:30, the FlightAware track data coverage ended with the airplane descending through 2,400 ft msl at a vertical speed about -600 fpm. Between 2039:31 and 2039:37, there was no ADS-B track dataavailable. At 2039:37, FAA ADS-B track data coverage resumed, with the airplane descending through 1,700 ft msl at a vertical speed about -10,000 fpm. At 2039:44, the FAA ADS-B track data ended with the airplane descending through 1,140 ft msl (about 216 ft above ground level) at a vertical speed about -7,200 fpm. A witness and her daughter were driving in their truck about 0.5 mile north-northwest of the accident site when they saw the airplane flying lower than what the witness thought was normal. They could not hear the airplane because they were inside their truck at the time, but they saw the airplane flying at slow speed, almost “hovering” in the air, before it suddenly entered a spiraling nosedive. The airplane completed at least 6 to 8 rotations in the descending spiral before it descended out of sight behind a hill. They subsequently called 911 to report the accident after they saw smoke and fire rising from the accident site. Figure 2. Plots of airplane pressure altitude, indicated altitude, ground speed, true airspeed, calibrated airspeed, and vertical speed. The Tarrant County Medical Examiner's Office performed the pilot’s autopsy. According to the pilot’s autopsy report, his cause of death was blunt force injuries with smoke inhalation and thermal injuries. The manner of death was accident. FAA Forensic Sciences Laboratory toxicological testing of postmortem specimens from the pilot did not detect any carboxyhemoglobin, ethanol, or tested-for drugs. Glucose was detected at 62 mg/dL in vitreous but was not detected in urine. At the time of the accident, day visual meteorological conditions prevailed with no clouds or visibility restrictions. Sunset was at 2022:09, about 34 minutes after the flight departed. The end of civil twilight was at 2048:57, about 9 minutes after the accident. The pilot’s flight logbook was not located. The airplane operator provided the pilot’s flight history from their reservation and billing system. Based on the available documentation, the pilot began flight training on August 22, 2023. The pilot had a total flight experience of 62.1 hours, of which 8.8 hours were flown as pilot-in-command (solo). The pilot had flown 59.4 hours in a Cessna 172C and 2.7 hours in a Cessna 150L. On May 6, 2024, the pilot received a solo flight endorsement for Cessna 172 and Cessna 150 airplanes from his flight instructor. The accident site was located in an open grass pasture near Godley, Texas. The airplane came to rest upright and wings level on a south-southeast heading. There was evidence of a significant postimpact fire that destroyed the entire cabin and cockpit. The instrument panel and all avionics were destroyed during the fire. All primary (elevators, ailerons, and rudder) flight control surfaces with their appropriate trim tabs and flaps were accounted for during the wreckage examination. Continuity of all primary flight control cables was confirmed from the cockpit to their respective flight control surface.Continuity of the elevator trim control cables were confirmed from the cockpit to the flight control trim surface. Continuity was confirmed by either visual and/or pulling the cable at one end to see the other same cable end and/or control surface move. The cockpit control column assembly exhibited thermal damage associated with the postimpact fire. The aileron chain remained intact and on each control column sprocket. The aileron forward bellcrank/arm assembly remained attached to the control column with attached cables. The elevator push/pull tube remained attached to the control column. The elevator forward bellcrank was destroyed during the postimpact fire, only leaving the steel clevises and attaching hardware intact, including a small piece of the elevator forward bellcrank. The empennage was thermally separated from the aft fuselage, but otherwise remained relatively intact and displayed minor impact-related damage. The empennage was displaced to the right. The rudder remained attached to the vertical stabilizer. The rudder surface was displaced to the right due to impact-related damage, but the rudder stops did not exhibit evidence of overtravel. The elevators remained attached to their respective horizontal stabilizers. The elevator trim actuator extension was about 1.8 inches, which corresponded to an elevator trim tab position about 7° trailing-edge-up. The ailerons remained attached to their respective wing attachment points. The flaps remained attached to their respective wing attachment points, except for those portions that were destroyed by fire. The flap handle was destroyed during the postimpact fire. The flap actuator/motor jackscrew found extended 5.9 inches, consistent with the wing flaps fully extended (40° down) at impact. The left fuel tank remained attached to the left wing and exhibited hydraulic deformation along the forward and bottom surfaces. The left fuel tank was breached due to fire-related damage, but contained a blue fluid consistent in odor to 100 low-lead aviation fuel. The right fuel tank was found separated from the right wing and exhibited impact and fire-related damage. The right fuel tank contained significant amounts of water consistent with intrusion from firefighting efforts and/or rain that occurred after the accident. The fuel lines, fuel shutoff valve, and the engine were destroyed during the fire. The fuel strainer assembly was found separated from its mount and exhibited thermal damage from the fire. The engine remained attached to the firewall through the engine mount. The engine was displaced down and to the right side of the airplane. The oil kidney tank remained attached to the engine crankcase but exhibited impact and fire-related damage. The starter remained attached to the rear of the engine. The rear accessory section was destroyed during the postimpact fire. Both magnetos were destroyed during the postimpact fire. The exhaust manifold remained attached to the engine but was cut tofacilitate the engine recovery and examination. The top spark plugs were removed and exhibited features consistent with normal engine operation. The engine crankshaft rotated by hand through the propeller. Internal engine and valvetrain continuity were confirmed as the crankshaft was rotated through the crankshaft flange. Compression and suction were noted on cylinder Nos. 2, 3, and 4 in conjunction with crankshaft rotation. No compression was noted on the No. 1 cylinder. The No. 1 cylinder exhaust valve did not move in conjunction with crankshaft/camshaft rotation. A borescope inspection of each cylinder did not reveal any anomalies with the cylinders, pistons, valves, valve seats, or bottom spark plugs. The spin-on type oil filter was found separated and thermally damaged. The No. 1 cylinder was separated from the engine crankcase to remove the intake and exhaust valves and their associated spring assemblies. The three exhaust valve springs were about 0.25 inch shorter than the intake valve springs. The height difference was consistent with the exhaust springs being compressed at impact and cooling in that position after the postimpact fire. The shorter exhaust valve springs did not allow the exhaust valve to seat, consistent with the lack of cylinder compression when tested. There was mechanical continuity between the throttle, mixture, and carburetor heat controls and their respective engine components. The carburetor and airbox exhibited significant thermal damage from the postimpact fire. The carburetor fuel bowl was breached; the carburetor did not contain any residual fuel. The throttle valve did not rotate due to impact-related damage. The 2-blade, fixed-pitch propeller blade remained attached to the engine crankshaft propeller flange and spacer. One propeller blade exhibited a slight bend/twist about 10 inches from the blade tip, a leading-edge gouge, and minor chordwise scratches. The other propeller blade was relatively undamaged and did not exhibit any bends, twists, leading edge damage, or chordwise scratches.