CEN15FA164

The pilot's decision to land during unfavorable wind conditions, which resulted in a loss of control due to settling with power. Contributing to the accident were the lack of an adequate approach path due to numerous obstructions and the lack of available guidance regarding the helicopter's performance capabilities in the right quartering tailwind condition.

The emergency medical service (EMS) helicopter was landing on a privately owned elevated heliport to pick up two medical crewmembers. The medical crewmembers had been dropped off with a patient on a preceding flight. During the preceding flight, the nurse thought about telling the pilot to abort the landing on the heliport because there was a lot of rolling and yawing, and he was having a hard time landing the helicopter. After the landing, the nurse and another medical crewmember stated that the pilot did not want to depart the heliport, but the medical crewmembers told the pilot that there may be potential arrivals of other EMS helicopters. The pilot chose to depart the heliport and obtained fuel at the operator's base of operations. For the return flight to pick up the two medical crewmembers, the wind had increased, and the helicopter approached the heliport in high-wind conditions and with a right, quartering tailwind. Also, the wind along with the surrounding buildings likely created a turbulent airflow/windshear environment in which the helicopter was operating as it approached for landing. The helicopter's operation in a high-power, low-airspeed condition in high-wind conditions, including a right quartering tailwind, likely resulted in a loss of control due to settling with power. A security video showed the helicopter on a northerly flightpath descending at about a 45-degree angle before impacting the ground and coming to rest on an approximate northerly heading. The pilot sustained fatal injuries due to the subsequent fuel tank fire/explosion, which otherwise would have been a survivable accident. A postaccident safety evaluation of the heliport showed that the final approach and takeoff area/safety area were obstructed by permanent and semi-permanent objects that pose a serious hazard to helicopter operations. These obstructions limited the available approach paths to the heliport, which precludes, at times, approaches and landings with a headwind. The helipad is privately owned; therefore, it is not subject to Federal Aviation Administration (FAA) certification or regulation. A review of the helicopter's flight manual revealed that there were no wind speed/azimuth limitations or suggested information available to pilots to base the performance capabilities of the make and model helicopter in their flight planning/decision-making process. Examination of the helicopter revealed no anomalies that would have precluded normal operation and showed engine power at the time of impact.  An accredited representative from the Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) was assigned to this investigation as the state of manufacture of the helicopter. The BEA provided comments on this report, which can be found in the docket.

The autopsy determined the cause of death was thermal burns and smoke inhalation. It described severe thermal injuries to the entire body including multiple thermal fractures and soot deposition in the respiratory tract from the trachea to the bilateral bronchial tree. Traumatic injuries included a hairline fracture of the frontal bone, a sternal fracture, and a fracture of the fifth cervical vertebra without evidence of a spinal cord injury. Subarachnoid blood was attributed to extension of blood from the fracture in the cervical spine. The autopsy identified coronary artery disease including 80 percent narrowing of the left anterior descending coronary artery. However, no focal lesions (evidence of an old or new heart attack) were identified in the heart muscle. On March 23, 2016, the NTSB issued Safety Recommendations A-16-11 and A-16-8 through -10 pertaining to Airbus Helicopters EC-130-B4 and AS-350-B3e. Two 2015 accidents, one of which involved N356AM, had impact forces survivable for occupants but fatal and serious injuries occurred because of postcrash fires that resulted from an impact-related breach in the fuel tanks. A post-crash fire and explosion occurred upon impact when the helicopter impacted the parking lot adjacent to the building entrance which was captured by a security video. The following two frames from a security camera show the explosion and fire that ensued after the helicopter's impact. Figure 3: The top video frame at 11:17:14 PM shows the fire/explosion during the impact of N356AM and the bottom frame at 11:17:17 PM shows a fire ball separated from the initial fire and moved upwards and to the left of the screen in a direction consistent with approximate wind direction. Destination Helipad The MO55 helipad is privately owned and was not subject to meeting regulatory requirements for helideck design requirements by the FAA and adherence to those regulatory requirements were voluntary. A letter by an FAA Airports Airspace Data Specialist, dated August 19, 1986, stated that following an on-site inspection of MO55 on May 7, 1986 or the 210 foot by 150 foot landing/takeoff area and a 50 foot by 50 foot touchdown area. The letter stated that there is adequate ingress/egress greater than 8-1, in two directions, 180 degrees apart. The letter stated that the aeronautical study of the proposed heliport [MO55] would adversely affect that safe and efficient use of airspace by an aircraft unless the following conditions are maintained: Clear approach/departure paths to the landing area for a minimum 8:1 glide slope . Obstruction clearance planes (glide slope), aligned with the direction of the approach/departure paths, extend outward and upward from the landing/takeoff area to the en route altitude at an angle of 8 feet horizontally to 1 foot vertically (8:1). A clear transitional surface for a minimum 2:1 slope. The transitional surface extends outward and upward from the edges of the landing/takeoff area and approach/departure clearance planes at an angle of 2 feet horizontally to 1 foot vertically (2:1) to a distance of 250 feet from the center of the landing and takeoff area and 250 feet from the centerline of the approach/departure clearance surfaces. The NTSB IIC requested that the FAA perform post-accident inspection of MO55, which was performed on April 16, 2015. The inspection results were documented in a Heliport Safety Evaluation Report, Case Number: 2015–ACE–1749–NRA. The report cited 10 obstructions within the final approach and takeoff area (FATO)/safety area of the heliport/helipad and 4 obstructions outside the FATO/safety area. The 10 obstructions outside the FATO/safety area had a ranged in azimuth from 005 – 236 degrees and there were no obstructions from 236 – 005 degrees, or west, northwest. Figure 1: Obstructions Outside the FATO/Safety Area Figure 2: Obstructions Inside the FATO/Safety Area The report's recommendations for ingress/egress stated: "The heliport FATO/safety area is obstructed by permanent and semi-permanent objects that pose a serious hazard to helicopter operations. The most serious obstructions cannot be easily lowered or removed. Flight Standards cannot recommend an approach/departure route into or out of a hazardous area that does not appear to have reasonable alternatives for mitigation. Therefore, no recommendation for ingress/egress is made in this case." The medic said if there is a lot of wind, it is "always weird" coming in for approach to land at MO55. The nurse said that her knowing the area and the St Louis University Hospital helipad (MO55), she knew that it was going to be a "hard landing" on a good day." A pilot that was not employed by Air Methods stated that he had flown in a Eurocopter "a handful of times. He said that flying into MO55 "is not the hardest pad but it's a difficult pad especially when the winds are at different angles and you have a lot of mechanical turbulence." The winds come around the building and can create a tailwind. Obstructions to the pad are the elevator shaft and buildings surround the pad. He takes new hire helicopter pilots and shows them the mechanical turbulence associated during flight training. He said that if "don't get set up at the right altitude and closure rate" for at MO55, you can "find yourself in a bad situation." He said the Baris hospital is "definitely more difficult to get into [than] MO55; you can have a headwind one minute and have a tailwind the next minute." He flies a Bell 206, which he said is not as strong as a Eurocopter 130 tailrotor. You can get into loss of tail rotor effectiveness approaching the wrong way during landing. His personal wind limitations are 25 knots with a gust spread of 10-12 knots. He feels "comfortable" with "steady winds of 25 knots." He said the Cardinal Glennon (MU52) hospital had a ground based helipad and using a ground pad required an arrangement to be made to transport a patient via an ambulance to the ground pad. Nearest Ground Based Helipad The nearest ground based helipad was MU52, which was located about 0.4 nautical miles west of MO55. The availability and its method of ground transportation from MO55 to MU52 prior to the accident was unknown to the investigation. Aircraft Performance Study There was no sufficient radar data or nonvolatile memory aboard the helicopter to perform a performance study of the helicopter's accident flight. Security Video A review of the security video cited in the Fire section of this report, showed at about 11:16:52 PM, a light consistent in white color and shape of the helicopter landing light shining onto the hospital building facing the parking lot entrance where the helicopter later impacted. The light then moves toward the right edge of the building and about 11:17:03 PM, the light moves left, off the building. About 11:17:06 PM, a flash of white colored light appears in the camera. About 11:17:08 PM, the light moves from right to left across the hospital building face as a declination at an estimated approximate angle of 45 degrees. About 11:17:11 PM, the helicopter comes into view and descending at a similar declination angle and direction as was the light. Settling With Power (Vortex Ring State) According to the Helicopter Flying Handbook (FAA-H-8083-21A), Chapter 11, Helicopter Emergencies and Hazards: "Vortex ring state describes an aerodynamic condition in which a helicopter may be in a vertical descent with 20 percent up to maximum power applied, and little or no climb performance. The term "settling with power" comes from the fact that the helicopter keeps settling even though full engine power is applied. In a normal out-of-ground-effect (OGE) hover, the helicopter is able to remain stationary by propelling a large mass of air down through the main rotor. Some of the air is recirculated near the tips of the blades, curling