NTSB Identification: SEA99LA016.
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Nonscheduled 14 CFR
Accident occurred Sunday, November 29, 1998 in IDAHO CITY, ID
Probable Cause Approval Date: 01/11/2000
Aircraft: McDonnell Douglas MD-900, registration: N977LF
Injuries: 4 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The McDonnell Douglas MD-900 medevac helicopter was dispatched to a car accident at a site characterized by high terrain and high trees. Prior to landing, the pilot requested information about wires and was advised by ground personnel that 'there were none.' Subsequent to landing, the pilot examined the landing site and proposed departure route for wires, and reportedly observed none. The departure from the site was conducted under dusk to dark night conditions. While climbing out vertically due to the narrow canyon conditions at the site, the helicopter struck unmarked transmission lines approximately 150 feet above ground. The pilot then determined that the helicopter was controllable and displayed no unusual flight characteristics, and chose to proceed to his destination. Post-flight examination revealed crazing of the windscreen and damage to four of the five main rotor blades requiring major repair/replacement.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot-in-command's not obtaining/maintaining clearance with the unmarked transmission lines. Contributing factors were environmental (dusk) conditions, the transmission lines, and both the pilot-in-command and the ground personnel not identifying the existence of the hazardous condition (high wires). Full narrative available
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