CEN23FA142 · Robinson Helicopter Company R44 II

With cloud ceilings at or below 1,000 ft above ground level (agl), the police department helicopter departed about 0226 to provide aerial support to law enforcement ground units that were conducting a high-speed pursuit of a vehicle. The helicopter flight crew (pilot and tactical flight officer) advised dispatch and ground units via radio that they were assisting and requested updates to the vehicle movement and location. ADS-B data showed the helicopter departed the airport to the south, turned west, then overflew a highway to the west of the departure airport. Unable to maintain safe pursuit of the vehicle, dispatch terminated the pursuit to all responding units, including the helicopter, via radio at 0235. There were no further communications received from the helicopter. About that time, the data showed the helicopter executed a shallow left deviation to the south of the highway. Following the deviation, the helicopter turned left, and the turn rate increased. A series of turns and altitude changes followed. The ADS-B data ended at 0238 at an altitude of about 1,450 agl. There were no witnesses to the accident. The pilot did not obtain a weather briefing or complete a department-required flight risk assessment before the flight. Although the accident was not survivable, police department personnel were unaware the helicopter had not returned to the base. Later that day, a family member reported that the tactical flight officer had not returned home, and his cellular phone was sending a signal from a remote area. The local sheriff’s department searched the area and located the helicopter at 1114. Postaccident examination of the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Debris location at the accident site and wreckage signatures are consistent with main rotor blade contact to the cockpit/cabin structure near the end of the flight. There was a stationary weather front in the vicinity of the accident site and that, combined with relatively moist surface air and low-level inversion, helped to create an environment conducive to the formation of low clouds and fog. Weather imagery showed a low cloud cover over the accident site at the accident time. The pilot did not hold an instrument rating. In addition, he had not received simulator training on strategies and techniques for recognizing, avoiding, and escaping inadvertent encounters with instrument meteorological conditions (IMC). Research indicates that inadvertent IMC training can improve pilot control and increase the likelihood of surviving such encounters. Such training might have recalibrated the pilot’s risk tolerance for situations involving continued visual flight rules (VFR) flight in IFR conditions, motivated him to avoid them, and helped him to maintain control of the helicopter in the event of an inadvertent encounter with IMC. Based on available flight data and weather information, it is likely that the pilot continued the vehicle pursuit into deteriorating weather conditions. After termination of the pursuit, the helicopter’s erratic maneuvers are consistent with the pilot experiencing spatial disorientation, a loss of control in flight, and inability to recover the helicopter. Ethanol was detected at a low level in cavity blood, a specimen type in which n-propanol was also detected. Ethanol was not detected in vitreous fluid, which is generally the specimen type best protected against postmortem ethanol formation. These results indicate that some or all of the small amount of detected ethanol may have been from postmortem production, and that ethanol effects did not likely contribute to the accident.

Verbatim NTSB analysis and probable cause from the NTSB dataset