NTSB Identification: CHI00FA262.
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Accident occurred Friday, August 18, 2000 in WATERTOWN, WI
Probable Cause Approval Date: 04/09/2001
Aircraft: Bell OH-58C, registration: N626SF
Injuries: 2 Fatal.

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 Milwaukee County Sheriff's Aviation Department was operating as a public-use operator. The helicopter was on a cross-country flight when it impacted rolling terrain in a sparsely populated area. Witness described fog in the area at the time of the accident. The Milwaukee County Sheriff's Aviation Division's standard operating procedures (SOP's) states under section 3/033.05 Basic VFR Weather Minimums, that 'Basic VFR weather minimums shall conform to those minimums outlined in FAR 91.155 and 91.157.' In addition to these requirements, the night weather minimums for operations outside the local flying area were a ceiling of 1,000 feet and a visibility of 3 miles. The chief pilot reported and also made an entry into the helicopter's discrepancy log indicating that the attitude indicator was inoperative on May 19, 2000. There was no entry regarding corrective action for the attitude indicator. On June 4, 2000 a draft of an MEL, prepared by the chief pilot, stated that the attitude indicator is, 'Not required during daylight. Not required at night when in VMC [visual metrological conditions] conditions'. FAA-H-8083-21, Rotorcraft Flying Handbook, Chapter 12, Attitude Instrument Flying, states under Attitude Indicator: 'The attitude indicator provides a substitute for the natural horizon. It is the only instrument that provides an immediate and direct indication of the helicopter's pitch and bank attitude...'

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The spatial disorientation by the pilot during continued flight into instrument conditions and the inadequate surveillance by the operator. The inoperative attitude indicator and night conditions were contributing factors.

Full narrative available

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