What happened
On December 10, 2012, at approximately 2016 CST, an MBB BK 117 A-3 helicopter, registration N911BK, crashed near Compton, Illinois. The aircraft, operated by Air Methods Corporation, was performing an on-demand air-taxi flight to pick up a patient for transport from Mendota Community Hospital to Rockford Memorial Hospital.
The flight departed from the Rockford Memorial Hospital Heliport at 1958. At 2010, the pilot reported being 12 minutes from the destination. However, at 2016, the pilot notified the dispatch center that the flight was being aborted due to encountered weather conditions. Flight track data showed the helicopter initiated a right turn away from a lighted windmill farm toward an area with sparse ground lighting, followed by a slight descent before the data ended.
The helicopter impacted a level, harvested agricultural field in a nose-low, inverted attitude. The crash resulted in 3 fatal injuries, claiming the lives of the pilot, the flight nurse, and the flight paramedic. The aircraft sustained substantial damage.
The investigation
Investigators examined the wreckage and found no evidence of mechanical malfunctions or failures that would have prevented normal operation. The engines, transmission, rotor systems, and flight controls were all found to be functional.
Meteorological analysis revealed that the area was experiencing light snow and overcast skies. Radar imagery indicated the presence of hydrometeors consistent with freezing drizzle and supercooled liquid water. While the pilot had access to computer-based weather resources, there was no record of what specific information was reviewed prior to the flight.
Findings
- The aircraft encountered inclement weather, including snow, freezing drizzle, and supercooled liquid water.
- The lack of ground lighting, combined with the encountered precipitation, likely reduced visibility and outside visual references.
- These conditions led to the pilot's spatial disorientation and subsequent loss of aircraft control.