What happened
On May 11, 2019, an Airbus Helicopters BK117 D-2, registration I-BKUP, was performing a Helicopter Emergency Medical Service (HEMS) mission at the Baggiovara Civil Hospital helipad in Italy. While the aircraft was in a stabilized hover at a low altitude during the final stages of landing, it suddenly began a series of large horizontal and vertical oscillations.
These uncontrolled movements lasted for approximately 90 seconds. During the event, the aircraft's flight data recorder (FDR) noted a "MAST MOMENT" exceedance and a "FADEC DEGRADED" warning, which investigators determined were consequences of the erratic maneuvers and attempts to stabilize the aircraft rather than the cause of the instability. Despite the intense movement and the presence of nearby obstacles such as trees and power lines, the pilot eventually regained control and completed the landing without further incident. There were no injuries to the six occupants, which included the pilot, a technical crew member, medical personnel, and a patient.
The investigation
The ANSV investigation focused on three primary areas: technical, environmental, and human factors.
Technical inspections of the BK117 D-2 and analysis of the FDR data revealed no mechanical failures or malfunctions that could have caused the oscillations. Meteorological data from nearby airports also ruled out significant weather disturbances or turbulence as contributing factors.
Analysis of the Cockpit Voice Recorder (CVR) revealed that while the flight began calmly, the pilot's behavior changed significantly during the landing. The pilot exhibited difficulty speaking and struggled to center the aircraft on the helipad. The investigation also examined the pilot's medical history and the operational configuration of the flight.
Findings
- The primary cause of the event was a sudden pilot incapacitation triggered by an underlying organic medical condition. This condition caused a temporary and sudden deterioration of the pilot's neurocognitive and neuromotor performance.
- The pilot's medical certification, while valid, did not include specific routine tests capable of detecting the particular pathology that led to the impairment.
- The flight was being conducted in a single-pilot configuration. The investigation concluded that the presence of a co-pilot would have likely allowed for a much faster recovery of the aircraft and mitigated the risk of collision with nearby obstacles.