CEN19FA185

The crew of the helicopter air ambulance flight was approaching the airport for landing in dark night instrument meteorological conditions (IMC) after delivering a patient to the hospital. The reported weather conditions about the time the pilot initiated the instrument landing system (ILS) approach included 1/2-mile visibility with haze, which then deteriorated to 1/4 mile, which was within the operator's approved visibility approach minimums. The paramedic onboard reported that he saw the runway environment through a thin layer of fog as the helicopter descended toward the decision height (DH) of 200 ft above ground level during the approach. After descending below the DH, with a power setting below 30% torque, the helicopter's pitch attitude increased from -3° (nose-down) to +20° (nose-up), its airspeed decreased from 100 to 50 knots, and the pilot declared a missed approach, likely due to a loss of visual contact with the runway environment. The pilot's increased collective input and the helicopter's decreasing airspeed resulted in an increase in torque, and the helicopter entered a right rotational yaw that accelerated into a spin. The helicopter subsequently impacted terrain near the runway. The dark night conditions at the rural airport resulted in little to no visual references during the pilot's transition to landing and the attempted missed approach. It is likely that the pilot became spatially disoriented, which led to the excessive pitch attitude, slow airspeed, his failure to recognize and arrest the right yaw, and the subsequent loss of control.

Spatial Disorientation The FAA's Airplane Flying Handbook (FAA-H-8083-3B) describes some hazards associated with flying when the ground or horizon are obscured. The handbook states, in part, the following: The vestibular sense (motion sensing by the inner ear) in particular can and will confuse the pilot. Because of inertia, the sensory areas of the inner ear cannot detect slight changes in airplane attitude, nor can they accurately sense attitude changes that occur at a uniform rate over a period of time. On the other hand, 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. FAA Instrument Approach Guidance FAA guidance for helicopter instrument approaches allows a reduction of the Category A visibility by half, but in no case less than 1/4 statute mile or 1,200 ft runway visual range (RVR). The approach can be initiated at any speed up to the highest approach category authorized; however, the speed on the final approach segment must be reduced to the Category A speed of less than 90 knots before the missed approach point in order to apply the visibility reduction. Operator Training and Guidance The operator's flight training and currency programs were all conducted inflight, as the only A109 simulator was based in Italy. Following a September 2016 accident that involved a loss of control during a missed approach in night IMC conditions, the operator started construction of a flight training device (FTD) for instrument procedures using an actual A109S cockpit. The FTD was not yet certified or in use at the time of the accident. Following the accident, the operator increased the minimum weather conditions required for their pilots to conduct an instrument approach to a cloud ceiling of 400 ft agl and 1 mile visibility. The helicopter was equipped with a 2-axis autopilot for lateral (roll) and longitudinal (pitch) control. The autopilot provided for limited yaw dampening, but no yaw control. Minimum airspeed to comply with IFR handling quality requirements for the helicopter was 55 knots. On June 28, 2019, about 0040 central daylight time, an Agusta Spa A109S helicopter, N11NM, was substantially damaged when it was involved in an accident at Brainerd Lakes Regional Airport (BRD), near Brainerd Lakes, Minnesota. The pilot and flight nurse were fatally injured, and the flight paramedic was seriously injured. The helicopter was operated by North Memorial Healthcare as a Title 14 Code of Federal Regulations Part 135 helicopter air ambulance flight. The flight was returning to BRD after delivering a patient to North Memorial Heliport (MY77), Robbinsdale, Minnesota. An onboard Appareo Vision 1000 device recorded flight data, cockpit imagery, and audio of the flight. The helicopter departed MY77 at 2348, and the pilot received an instrument flight rules clearance from air traffic control (ATC)to climb to 6,000 ft mean sea level (msl) and fly direct to BRD. At 2356, while holding an iPad, the pilot stated on intercom to the paramedic and/or flight nurse that visibility at BRD was "1 mile, looks good." The pilot requested the instrument landing system runway 23 (ILS RWY 23) approach and informed the controller that he had obtained the current weather at BRD. At 0028, the pilot selected the BRD automated surface observing system (ASOS) frequency. The ASOS transmission included a ceiling of 200 ft above ground level (agl) and 1/4-mile visibility with fog. The controller cleared the helicopter for the ILS RWY 23 approach. Shortly thereafter, the ASOS-transmitted weather included 1/2-mile visibility with haze, and the pilot stated "awesome, 1/2 we're legal" on the intercom. The pilot subsequently activated the runway lights. At 0034:35, the helicopter began a descent on the ILS glideslope with the autopilot coupled. About 5 seconds later, the pilot appeared to turn on the helicopter's landing light and/or search light. At 0036:30, the helicopter passed the final approach fix (5.3 miles from Runway 23) at 93 knots. At 0036:37, the ASOS-transmitted weather included 1/4-mile visibility with haze and a sky condition of 200 ft vertical visibility. After arriving at the ILS decision height, the pilot selected the altitude hold mode on the flight director and about 1 second later, decoupled the autopilot (pitch and roll steering modes). The radar altimeter read 130 ft agl. Over the next 14 seconds, with a power setting below 30% torque, the helicopter's pitch increased from -3° (nose-down) to +20° (nose-up) and the radar altimeter increased to 230 ft agl. As airspeed decreased below 50 knots, the pilot selected vertical speed, and heading modes on the flight director. The helicopter's power increased rapidly through 40% torque and the airspeed decreased through 25 knots. Based on a GPS groundspeed of 40 knots, the airborne tailwind was about 15 knots. At 0039:38, the pilot announced a go-around. The helicopter's power increased past 80% torque, and the airspeed was 0 knots. The flight instruments indicated that the helicopter had entered a right rotational yaw and the radar altimeter read 300 ft agl. The helicopter's right yaw continued to increase; the power setting rose above 110% torque and the airspeed remained near 0 knots. The last recorded information, at 0039:57, indicated that the helicopter was about 100 ft agl. The power setting was below 30% torque and the pilot had selected the "ALT" (altitude hold) button on the flight director. Recorded images of the approach and attempted go-around did not provide a view of the runway environment or weather conditions. Following the accident, the flight paramedic (seated in the left forward seat) recalled that the runway lights and surface were visible below a thin fog layer during the approach. As the helicopter approached the runway, he noticed clouds to the side and recalled the pilot statingthat the weather conditions were foggy and that a go-around was needed. The helicopter subsequently spun to the right and impacted the ground. An autopsy was performed on the pilot and flight nurse by the Ramsey County Medical Examiner, St. Paul, Minnesota. The cause of death was multiple traumatic injuries. The Federal Aviation Administration (FAA) Forensic Sciences Laboratory performed toxicological testing on the pilot. The tests were negative for all screened-for drugs, carbon monoxide, and alcohol. BRD was located in a rural area with few ground lights, and there was no moon illumination at the time of the accident. Airport personnel stated that several lakes near BRD would often generate patchy fog and visibility could vary significantly at different locations on the airport. The BRD ASOS was located about 600 ft left of runway 23 and about 1,200 ft from the runway threshold. BRD did not have equipment to measure runway visual range (RVR) for the touchdown zone. At the time of the accident, the ASOS reported wind from 040° at 5 knots, 1/4 statute mile visibility, haze, vertical visibility of 200 ft agl, temperature of 19°C and a dew point temperature of 17°C. The terminal aerodrome forecast (TAF) valid for BRD about the accident time included wind from 020° at 4 knots, 1 1/2 statute miles visibility, haze, and a clear sky. An AIRMET advisory for instrument flight rules (IFR) conditions was valid at the accident time. The pilot's most recent Part 135 competency/proficiency check occurred on March 12, 2019. During the 90 days before the accident, the pilot logged 27 landings at night, 16 instrument approaches, 1 flight hour of actual instrument time, and 57 hours of simulated instrument time. The pilot's total actual instrument time flown was 41 hours. The FAA Civil Aerospace Medical Institute (CAMI) reviewed the helicopter's seats, restraints, and helmet specifications and the effects of the impact with terrain at a high vertical velocity. No anomalies were noted. The operator's communication center first attempted radio contact with the helicopter crew about 15 minutes after the accident and the paramedic made a mayday radio transmission about 22 minutes after the accident. Emergency response personnel located the helicopter about 41 minutes after the accident. The low-visibility weather conditions contributed to the delayed arrival of first responders. The FAA did not require that the operator have an operational control center (OCC). Following the accident, the operator made communication center training and process improvements, including timely identification of an aircraft potentially in distress. The helicopter impacted a grassy area south of runway 23 and came to rest upright and nearly intact on a heading of 074°. The main fuselage and tail boom exhibited crushing consistent with a high-velocity vertical descent and impact. (See Figure 1.) The helicopter was upright and nearly intact, with no movement from the initial impact point.There was no evidence of a postcrash fire. The ground adjacent to the wreckage was soaked with fuel and the smell of fuel was present at the accident site. Figure 1. View of Helicopter at Accident Site Examination of the helicopter and review of recorded flight information revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.