CEN23FA220

Before taking off on an instrument-flight-rules (IFR) cross-country flight, the pilot obtained a standard weather briefing of the forecast and observed weather conditions along the flight route, which included thunderstorms, convective Significant Meteorological Information (SIGMETs), and Airmen’s Meteorological Information (AIRMETs) for icing conditions. A review of air traffic control (ATC) information revealed that, while the pilot was en route to the destination airport, an air traffic controller told the pilot that there was moderate to heavy precipitation about 5 miles ahead and the pilot acknowledged. About 4 minutes later, the pilot requested a lower altitude due to ice accumulation. ATC gave the pilot a block altitude to maintain and the pilot began to descend the airplane. About 40 seconds later, ATC told the pilot he could descend below the block altitude if needed. The pilot acknowledged by saying, “roger.” Immediately after the pilot acknowledged that he could go lower, ATC told him that if he was turning toward the west, there was extreme precipitation that extended to the southwest. The pilot did not respond. ATC made several subsequent attempts to contact the pilot; however, the pilot never responded. The airplane impacted a grass field and was destroyed. Airplane debris was scattered in the field for several hundred feet. The rudder and vertical stabilizer separated from each other and most of the pieces of the rudder and vertical stabilizer were found before the impact site in a tree and on the ground. The investigation estimated the airplane’s airspeed based on recorded ADS-B data and atmospheric conditions at the time of the accident. The ADS-B pressure altitude data was used to calculate the vertical airspeed at the end of the flight based on the rate of descent. The computed maximum airspeed at the last reliable pressure altitude, about 10 seconds before impact, was about 286 KTAS, which surpassed the never exceed speed (Vne) listed in the airplane’s pilot operating handbook of 210 knots. Analysis of the ADS-B data also revealed that, in the final 2 minutes of flight, the airplane pitched back and forth between 10° above the horizon and -60° below the horizon and rolled to the right at bank angles between 10° and 120°. Examination of the separated rudder and vertical stabilizer depicted signatures of overstress, and the location where they were found indicated that they separated from the airplane before impact. However, due to their proximity to the rest of wreckage, the separation likely occurred immediately before impact and the inflight breakup was not causal to the accident. The vertical stabilizer and rudder separated from the empennage due to “rudder flutter” when the airplane exceeded the Vne for the airplane. Examination of the engine and remaining systems revealed no mechanical anomalies. Based on the pilot’s reported accumulation of ice, the adverse weather conditions, and the airplane’s variations in pitch androll in the final minutes of flight, the pilot likely experienced a loss of control after encountering adverse weather due to a combination of ice accumulation on the airplane’s control surfaces. Toxicological testing revealed ethanol was present in samples taken during the autopsy. Given the putrefaction of the samples, it is likely that all detected ethanol was the result of postmortem production.

The airplane’s transponder/altimeter/static biennial certification was completed in April 2023. The Vne listed in the pilot operating handbook for the RV-7 was 210 knots. On June 2, 2023, about 0907 central daylight time, a Van’s Aircraft RV-7, N977RV, was destroyed when it was involved in an accident near Gibbon, Nebraska. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot filed an instrument-flight-rules (IFR) flight plan and departed on a multi-leg cross-country personal flight in the airplane. Before departure, the pilot obtained a standard weather briefing of the forecast and observed weather conditions along the flight route, which included thunderstorms, convective SIGMETs, and AIRMETs for icing conditions. ADS-B data revealed that the airplane departed the Rocky Mountain Metropolitan Airport (BJC), Denver, Colorado, at 0710 mountain daylight time and proceeded direct toward Red Oak Municipal Airport (RDK), Red Oak, Iowa. A review of ATC information revealed that, about 0900 central daylight time, the FAA Minneapolis Air Route Traffic Control Center controller told the pilot that there was heavy precipitation in the immediate vicinity ahead of him, and the pilot acknowledged. About 4 minutes later, the pilot requested a lower altitude due to ice accumulation. ATC acknowledged the request and gave the pilot a block altitude between 11,000 and 15,000 ft msl. The pilot acknowledged and began a descent from about 15,000 ft. About 40 seconds later, the ATC controller told the pilot he could descend below 11,000 ft if he needed to go lower. The pilot acknowledged by saying, “roger.” Immediately after the pilot acknowledged that he could go lower, the ATC controller told him that if he was turning toward the west, there was extreme precipitation, and the precipitation extended to the southwest. The pilot did not respond. ATC attempted to contact the pilot several times after that with no response. Flight track data indicated that, shortly after the pilot’s last recorded transmission, he began a gradual right turn to the west and then continued to spiral downwards. A witness in the vicinity of the accident site reported that, shortly after 0900, she was sitting on her porch looking to the north and saw the airplane pass in front of her. The airplane was traveling west to east and then made a sharp right turn to the southwest toward Interstate 80. The airplane flew over her house and then she lost sight of it; however, she said the airplane was “making a lot of power” and it was “accelerating excessively.” Shortly after she lost sight of the airplane, she heard a loud bang. Dashboard camera footage from a car traveling east bound on Interstate 80 captured the airplane descending in a nose-down attitude. The airplane impacted an open grassy area surrounded by trees about 260 ft south of Interstate 80. Data was recovered from the iFly Electronic Flight bag applicationon the iPad that was carried in the airplane, including GPS altitude and groundspeed information at the end of the flight. Airspeeds were estimated based on the recorded ADS-B data and atmospheric conditions at the time of the accident. At 09:06:52, the maximum airspeed was about 170 knots calibrated airspeed (KCAS) and 204 knots true airspeed (KTAS) before most of the ADS-B data became unreliable. However, the ADS-B pressure altitude data was deemed reliable beyond this point and was used to calculate the airspeed based on the rate of descent. The computed maximum vertical airspeed at the last reliable pressure altitude of 7,900 ft msl occurred at 09:07:00 and was about 286 KTAS. Review of the ADS-B data also revealed that in the final 2 minutes of flight the airplane pitched back and forth between 10° above the horizon and -60° below the horizon and rolled to the right at bank angles between 10° and 120°. An autopsy of the pilot was performed at the Douglas County Morgue, Nebraska, on June 5, 2023. The cause of death was listed as undetermined due to the amount of remains that were recovered. The FAA Forensic Science Laboratory performed toxicological testing. Caffeine and ethanol (in the presence of decomposition) were detected. The WSR-88D Level-II base reflectivity weather radar imagery from the Hastings, Nebraska, site (UEX) is presented in figure 1. UEX was located about 30 miles southeast of the accident location. The airplane’s flight path is denoted by a white line and the accident site is denoted by a purple circle. The end of the accident airplane’s flight path coincided with a cell of light-to-extreme reflectivity. Figure 1. UEX Level-II base reflectivity product from a sweep initiated at 0907:41. A review of the Earth Networks Total Lightening Network lightning data database and a region surrounding the location revealed no flash total lightning activity between 0855 and 0910 within 10 miles of the accident location inside that region. A High-Resolution Rapid Refresh model sounding for near the accident site at 0900 revealed scattered to overcast clouds between 8,000 ft msl to above 17,000 ft msl. The freezing level was at 12,575 ft and a trace of light rime icing was noted at about 12,700 ft. No significant turbulence was noted between 5,000 ft and 35,000 ft. The wind near 10,000 ft was generally out of the south at about 20 knots. At 0855 the National Weather Service Aviation Weather Center issued Convective SIGMET 65C that was active for the accident location and valid until 1055. It warned of an area of embedded thunderstorms with tops to 34,000 ft. The thunderstorm was moving from 180°at 20 knots. The pilot received a standard weather briefing on the morning of the accident. The briefing included information regarding Convective SIGMETs, low visibility in the vicinity of his flight route, and ice. A review of the pilot’s logbook showed that the pilot was instrument current, completing 15 instrument approaches in the previous 5months, of which 2 were completed with a flight instructor the day before the accident. The pilot’s flight instructor stated that the pilot wanted to be “prepared and instrument current” before departing on the trip. The flight instructor also stated that the pilot did not have a lot of current practice flying in instrument meteorological conditions, but she felt that the pilot was in a “good state” and took safety seriously. According to the pilot’s logbook, he had accumulated about 27 hours of actual instrument flight experience and the last time he flew in actual instrument conditions was in August 2022. On April 21, 2023, the pilot obtained a FAA 3rd class medical certificate with a waiver/limitation that he must wear corrective lenses while flying. It is unknown if the pilot was wearing corrective lenses at the time of the accident. The airplane impacted an open grassy area surrounded by trees about 260 ft south of Interstate 80 near Gibbon, Nebraska, at an elevation of 2,070 ft msl. The airplane traveled about 100 ft from the impact site to the main wreckage. The rudder and vertical stabilizer separated from each other and most of the pieces of the rudder and vertical stabilizer were found before the impact site (figure 2). The rudder was in three pieces that had a jagged sawtooth appearance (figure 3). The first piece was located about 120 ft before the impact site, the second piece was located about 25 ft before the impact site, and the third piece was in a tree about 30 ft north of the impact site. The vertical stabilizer was located about 55 ft northeast of the impact site. Impact ground scarring was consistent with nose, wing, and main landing gear impact. The propeller was embedded in the ground at the impact site. The engine separated and was found about 40 ft after the impact site. The main landing gear assembly was also found near the engine. The debris field contained fragmented engine components, instrument panel, windshield, and multiple pieces of fiberglass skin. The main wreckage came to rest upright on a 266° heading, and consisted of the fuselage, wings, and horizontal stabilizer. The debris field was generally aligned on a 257° heading. Both wings remained attached to the fuselage and were crushed along the leading edge. The aileron and flap on the right wing remained attached. The pushrods were broken, but the rods were able to be traced back to the control stick. The flap on the left wing was attached. The left aileron was impact separated and found about 15 ft south of the main wreckage. Control continuity to the flap was unable to be determined due to impact damage. The propeller was separated from the flange, but both blades were still attached at the hub. The blades were twisted, and they exhibited chordwise scratching and bending along the blade length. The fuel system and engine were crushed, fragmented, and cracked, rendering them unable to be functionally tested. Figure 2. Drone photo of accident site (courtestyof Nebraska State Police) Figure 3. Vertical stabilizer and rudder with jagged a sawtooth appearance.