NTSB Identification: CHI04FA107.
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Nonscheduled 14 CFR
Accident occurred Tuesday, April 20, 2004 in Boonville, IN
Probable Cause Approval Date: 06/08/2005
Aircraft: Bell 206L-1, registration: N137AE
Injuries: 1 Fatal,3 Serious.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The helicopter collided with up sloping terrain during a night air medical flight. The accident occurred while transporting a patient from one hospital to another. Examination of the accident site and wreckage revealed the helicopter impacted the terrain in a level flight attitude. The accident site was at an abandoned strip mine located in a rural area. The area contained very few ground structures to provide reference lighting. During post accident interviews the pilot stated that he remembered picking up the patient and the next thing he remembered is the helicopter tumbling. The flight nurse and paramedic on board did not recall there being any indication of a problem prior to impact. The destination hospital is located inside the Class C airspace of the Evansville Regional Airport (EVV). The air traffic control facility at EVV closes at 2300. Between 2328 and 2339, the pilot made 12 attempts to establish contact with approach control as he approached the Class C airspace. There was a time zone change at EVV 16 days prior to the accident. Examination of the cockpit revealed the altimeter was set at 30.08 inches of mercury. The current altimeter setting was 29.77 inches of mercury. This resulted in the altimeter indicating about 310 feet higher then the actual altitude of the helicopter. The pilot who flew the helicopter prior to the accident flight reported the radar altimeter was operating erratically. This pilot and the mechanic who maintained the helicopter, both stated the accident pilot was informed of the problem. Bench testing of the radar altimeter failed to duplicate the reported erratic operation. The decision height (DH) bug on the radar altimeter was found set to 60 feet. Company policy is that the DH bug be set to 500 feet during visual night operations. Examination of the airframe, engine, and flight controls failed to reveal any mechanical failure/malfunction.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's inadequate planning/decision which resulted in his failure to maintain terrain clearance. Contributing factors were the pilot's inadequate preflight planning, his diverted attention, and the dark night conditions. Full narrative available
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