CEN23FA125

The pilot’s initiation of the visual flight into instrument meteorological conditions, which resulted in spatial disorientation and a subsequent loss of helicopter control. Contributing to the accident was the pilot’s flicker vertigo during the flight.

The helicopter impacted terrain shortly after the non-instrument-rated pilot took off from his residence for the night flight. A neighbor observed the helicopter’s red anti-collision (strobe) light operating as it departed. The neighbor reported that it was extremely foggy and she could “barely see” her boat dock, which was about 75 ft away. There were no known witnesses to the accident. The helicopter impacted the terrain and a postimpact fire ensued. Recorded data from on board the helicopter showed that it departed from a road next to the pilot’s residence and traveled toward a swamp area that contained little to no ground reference lighting. ADS-B data for the accident flight showed a fight path starting from an area near the pilot’s residence. The helicopter traveled to the east, passed over a lake, and then performed a turn to the north. The helicopter climbed and then descended toward the south. The ADS-B data terminated over an open field next to a home. The direct distance from where the helicopter departed from to the accident site was about 0.25 miles. While a postimpact fire consumed most of the wreckage, an examination revealed no preimpact mechanical malfunctions or failures with the airframe or the engine. The helicopter was found to be equipped for instrument flight; however, the helicopter was not certified for instrument flight rules. A search revealed that the pilot did not receive an official weather briefing before initiating the flight. The pilot’s toxicological testing detected ethanol at a very low level in cavity blood. Ethanol was not detected in vitreous fluid or urine. These results indicate that some or all of the detected ethanol may have been from postmortem production. It is unlikely that ethanol contributed to the accident. The toxicological evidence also indicates that the pilot had used cetirizine. Whether the pilot was experiencing some sedating effects of this medication at the time of the accident is uncertain. Based upon the pilot’s initiation of flight at night in instrument meteorological conditions (IMC), it is unlikely that the pilot’s use of cetirizine contributed to the accident. The autopsy’s cardiac findings are non-specific and unlikely of significance to the accident. The pilot had the anti-collision (strobe) light activated during the flight. Usage of an anti-collision (strobe) light during flight through clouds can cause flicker vertigo and subsequent spatial disorientation. In addition to spatial disorientation, the pilot likely also experienced flicker vertigo before the impact with terrain. It is likely the non-instrument-rated pilot’s decision to initiate flight in night IMC resulted in spatial disorientation, a loss of control during the initial climb, and a subsequent impact with terrain.

The closest official weather reporting location was the Calhoun County Airport (PKV), Port Lavaca, Texas, located about 20 miles northwest of the accident site. At 2155, the Automated Weather Observation System reported wind from 160° at 6 kts, visibility 5 miles with mist, and the ceiling broken at 500 ft above ground level. Airmen’s Meteorological Information Sierra for IFR conditions was issued at 2200 for ceilings below 1,000 ft and visibility below 3 miles with mist and fog present. At the time of the accident, the sun was more than 15° below the horizon, while the moon was about 50° above the horizon at an azimuth of 109°.The phase of the moon was a full moon and was 99.7% illuminated. The FAA contract Automated Flight Service Station provider Leidos had no contact with the pilot on March 6, 2023, for any weather briefing or to file any flight plans. No third-party vendors using the Lockheed Flight Service (LFS) system had contact with the pilot. A separate search of ForeFlight indicated that they also had no account with the pilot and no record of any weather briefings or flight plans being filed. The non-instrument-rated pilot was employed as a medical doctor. The pilot had attended the RHC Pilot Safety Course at the factory in Torrance, California, in September 2008. The RHC flight instructor reported that the pilot had a “good attitude to aviation safety” on the pilot evaluation form. The pilot’s logbook was not available for review. A review of FAA records showed that the pilot purchased the helicopter on June 4, 2008. The helicopter was previously involved in an accident on February 14, 2014; however, the pilot was not on board the helicopter when the previous accident occurred. The helicopter was found to be equipped for instrument flight; however, the helicopter was not certified for instrument flight rules (IFR) by the FAA. The helicopter was not equipped with a radar altimeter, nor was it required to be by the FAA. The FAA-approved RHC R-44II Pilot’s Operating Handbook and Rotorcraft Flight Manual discusses the lighting system and states in part: A red anti-collision light is installed on the tail cone and is controlled by the strobe switch. Position lights are installed on each side of the cabin and in the tail and are controlled by the navigation lights switch. The red anti-collision (strobe) light contains light emitting diodes (commonly referred to as LEDs). The FAA Pilot’s Handbook of Aeronautical Knowledge FAA-H-8083-25C discusses night vision illusions and defines flicker vertigo: A light flickering at a rate between 4 and 20 cycles per second can produce unpleasant and dangerous reactions. Such conditions as nausea, vomiting, and vertigo may occur. On rare occasions, convulsions and unconsciousness may also occur. Proper scanning techniques at night can prevent pilots from getting flicker vertigo. The FAA Helicopter Flying Handbook FAA-H-8083-21B discusses flicker vertigo and states in part: Flashing anticollision strobe lights, especially while the aircraft is in the clouds, can also produce this effect. The FAA Office of the Chief General Counsel released a letter on January 11, 2011, that discusses the usage of anticollision lights under 14 CFR Part 91.209 and states in part: The FAA agreed that “the use of a high intensity anticollision light,” such as a strobe light, could create unsafe conditions by “inducing vertigo and causing spatial distortion.” 14 CFR Part 91.209, Aircraft Lights, discusses the use of anticollision lights and states in part: However, the anticollision lights need not be lighted when the pilot-in-command determines that, because of operating conditions, it would be in the interest of safety to turn the lights off. The Travis County Medical Examiner’s Office performed the pilot’s autopsy. According to the pilot’s autopsy report, his cause of death was blunt trauma, and his manner of death was accident. Examination of the heart revealed ventricular and atrial dilatation, and the heart was described as enlarged. The pilot’s coronary arteries were reported to be normal without atherosclerotic disease. The remainder of the autopsy including the heart did not reveal other significant natural disease. The autopsy report stated that the Medical Examiner’s Office performed postmortem toxicological testing that did not detect the presence of ethanol or common drugs of abuse or elevation of carbon monoxide. The FAA Forensic Sciences Laboratory performed toxicology testing of postmortem specimens from the pilot. Ethanol was detected in cavity blood at 0.012 g/dL; ethanol was not detected in vitreous fluid or urine. N-propanol and acetone were detected in cavity blood and were not detected in vitreous fluid or urine. Cetirizine was detected in cavity blood at 121 ng/mL and in urine at 794 ng/mL. Norchlorcyclizine was detected in cavity blood and urine. Sildenafil was detected in urine; testing of cavity blood for sildenafil was inconclusive. Desmethylsildenafil and acetaminophen were detected in cavity blood and urine. Examination of the airframe revealed flight control continuity. The removable collective and cyclic controls were not installed; however, the removable anti-torque pedals were installed. The navigation light switch and the anti-collision (strobe) light switch were both found in the on positions. All the cockpit warning lights were found intact, and the filaments were checked with no signs of filament stretching present. An unknown make and model emergency locator transmitter (ELT) was found with fire damage. The ELT antenna was found connected and the ELT was found in its mount attached to the airframe. Due to fire and impact damage, airframe to engine control continuity could not be established. Examination of the engine revealed internal engine continuity. The crankshaft was rotated by turning the engine around the cooling fan. Continuity of the crankshaft to the rear gear and to the valvetrain was confirmed. Compression and suction were observed from all six engine cylinders. The interiors of the cylinders were viewed using a lighted borescope and no damage to the pistons, cylinder walls, or valves was observed. On March 6, 2023, about 2157 central standard time, a Robinson Helicopter Company (RHC) R-44II helicopter, N494SH, was destroyed when it was involved in an accident near Port O’Connor, Texas. The pilot and passenger sustained fatal injuries. The helicopter was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. A review of ADS-B data showed that earlier on the day of the accident, the helicopter departed from the pilot’s residence in Port O’Connor, Texas, and flew to the Pearland Regional Airport (LVJ), Pearland, Texas. The helicopter then returned to the pilot’s residence. The helicopter was equipped with a Garmin Aera 796 unit. The limited data available for the unit showed the helicopter departed from a road next to the pilot’s residence and traveled to the northwest, with the data terminating shortly thereafter. The limited ADS-B data for the accident flight showed a fight path starting from an area just to the north of the pilot’s residence. The helicopter traveled to the east, passing over a lake, and then performed a turn to the north near a road. The helicopter climbed and then descended toward the south. The ADS-B data terminated over an open field next to a home. The direct distance from the departure location to the accident site was about 0.25 miles on a northeast heading. The area to the east of the accident site consisted of swamp with no observed ground lighting sources. The helicopter came to rest on a flat grass field, where a postimpact fire consumed most of the wreckage. According to the passenger’s daughter, the destination at the time of the accident was LVJ. A neighbor, whose home was about 1,000 ft southwest of where the helicopter took off, observed the helic