History of Flight
On June 28, 2019, at about 0040 central daylight time, an Agusta Spa A109S helicopter, registration N11NM, was substantially damaged in an accident at Brainerd Lakes Regional Airport (BRD), near Brainerd Lakes, Minnesota. The helicopter was operated by North Memorial Healthcare as a Title 14 Code of Federal Regulations Part 135 air ambulance flight. The pilot and flight nurse were fatally injured, and the flight paramedic was seriously injured.
The flight was returning to BRD after delivering a patient to North Memorial Heliport (MY77) in Robbinsdale, Minnesota. An onboard Appareo Vision 1000 device recorded flight data, cockpit imagery, and audio. The helicopter departed MY77 at 2348, and the pilot received an instrument flight rules clearance from air traffic control to climb to 6,000 ft mean sea level and fly direct to BRD.
At 2356, while holding an iPad, the pilot stated on intercom 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 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 and 1/4-mile visibility with fog. The controller cleared the helicopter for the ILS RWY 23 approach. Shortly thereafter, the ASOS transmitted 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 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. 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° to +20° and the radar altimeter increased to 230 ft agl. As airspeed decreased below 50 knots, the pilot selected vertical speed and heading modes. The helicopter's power increased rapidly through 40% torque and airspeed decreased through 25 knots. Based on 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 airspeed was 0 knots. Flight instruments indicated a right rotational yaw and the radar altimeter read 300 ft agl. The right yaw continued to increase; power rose above 110% torque and airspeed remained near 0 knots. The last recorded information, at 0039:57, indicated the helicopter was about 100 ft agl, power below 30% torque, and the pilot had selected the altitude hold button on the flight director. Recorded images did not provide a view of the runway environment or weather.
Following the accident, the flight paramedic 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 stating that the weather was foggy and a go-around was needed. The helicopter spun to the right and impacted the ground.
Personnel Information
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.
Aircraft Information
The helicopter was equipped with a 2-axis autopilot for lateral and longitudinal control, providing limited yaw dampening but no yaw control. Minimum airspeed to comply with IFR handling quality requirements for the helicopter was 55 knots.
Meteorological Information
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 noted that several lakes near BRD often generated 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 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 19°C, and dew point 17°C. The terminal aerodrome forecast valid for about the accident time included wind from 020° at 4 knots, 1 1/2 statute miles visibility, haze, and clear sky. An AIRMET advisory for instrument flight rules conditions was valid at the accident time.
Wreckage and Impact Information
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. There was no evidence of a postcrash fire. The ground adjacent to the wreckage was soaked with fuel. Examination of the helicopter and review of recorded flight information revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.
Additional Information
Spatial Disorientation
The FAA's Airplane Flying Handbook describes that the vestibular sense can confuse the pilot, leading to false sensations and spatial disorientation when the ground or horizon is obscured.
FAA Instrument Approach Guidance
FAA guidance for helicopter instrument approaches allows a reduction of Category A visibility by half, but not less than 1/4 statute mile or 1,200 ft RVR. The speed on the final approach segment must be reduced to less than 90 knots before the missed approach point to apply the visibility reduction.
Operator Training and Guidance
The operator's flight training and currency programs were conducted inflight. Following a September 2016 accident, the operator started construction of a flight training device using an A109S cockpit, but it was not yet certified or in use at the time of the accident. After the accident, the operator increased minimum weather conditions for instrument approaches to a ceiling of 400 ft agl and 1 mile visibility.
Medical and Pathological Information
An autopsy performed on the pilot and flight nurse determined the cause of death as multiple traumatic injuries. Toxicological testing on the pilot was negative for all screened-for drugs, carbon monoxide, and alcohol.
Survival Aspects
A review of the helicopter's seats, restraints, and helmet specifications found no anomalies. The operator's communication center first attempted radio contact about 15 minutes after the accident; the paramedic made a mayday transmission about 22 minutes after the accident. Emergency personnel located the helicopter about 41 minutes after the accident. Low-visibility weather conditions contributed to the delayed arrival of first responders. The FAA did not require an operational control center for the operator. After the accident, the operator made communication center training and process improvements.