Accident MBB BK 117A-3 N911BK,
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ASN Wikibase Occurrence # 151139
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Date:Monday 10 December 2012
Type:Silhouette image of generic BK17 model; specific model in this crash may look slightly different    
MBB BK 117A-3
Owner/operator:Air Methods Corporation
Registration: N911BK
MSN: 7099
Year of manufacture:1986
Total airframe hrs:10836 hours
Engine model:Lycoming LTS101-650B-1
Fatalities:Fatalities: 3 / Occupants: 3
Aircraft damage: Substantial
Location:near Rochelle, IL -   United States of America
Phase: En route
Departure airport:Rockford, IL (LL83)
Destination airport:Mendota, IL (14IL)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
The medical transport helicopter was on a night flight conducted under visual flight rules (VFR) to pick up a patient for transport. The pilot had computer-based weather information available, but it is unknown what information he reviewed before deciding to accept the flight. Weather observation stations along the route of flight were reporting VFR conditions around the time that the pilot accepted the flight. About 17 minutes into the flight, the pilot reported to the receiving hospital’s communications center that he was aborting the mission due to encountering inclement weather and was returning to base. Flight track data indicated that the helicopter initiated a right turn at this time, away from a nearby lighted windmill farm toward an area with sparse ground lighting . The flight track then showed a slight descent before the end of the data. The last recorded position was about 0.75 miles east-southeast of the main wreckage site. The helicopter impacted an agricultural field in an inverted, nose-low attitude. Examination of the wreckage revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.  Weather data and reports from first responders indicated that the flight likely encountered areas of snow, freezing drizzle, and supercooled liquid water. The lack of ground lighting combined with the precipitation encountered likely reduced the visibility and outside visual references available to the pilot resulting in spatial disorientation and subsequent loss of control.

Probable Cause: The inadvertent encounter with inclement weather, including snow, freezing rain, and reduced visibility conditions,  which led to the pilot’s spatial disorientation and loss of aircraft control.

Accident investigation:
Investigating agency: NTSB
Report number: CEN13FA096
Status: Investigation completed
Duration: 2 years
Download report: Final report




Revision history:

11-Dec-2012 00:35 gerard57 Added
11-Dec-2012 00:45 harro Updated [Aircraft type, Registration, Cn, Narrative]
11-Dec-2012 11:22 RobertMB Updated [Time, Aircraft type, Registration, Cn, Location, Source, Narrative]
16-Dec-2012 09:57 TB Updated [Location, Departure airport, Destination airport, Source, Narrative]
29-Mar-2015 12:21 Aerossurance Updated [Operator, Source, Narrative]
29-Mar-2015 12:23 Aerossurance Updated [Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
28-Nov-2017 14:00 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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