NTSB Identification: SEA00FA021B
Accident occurred Wednesday, November 17, 1999 in SEATTLE, WA
Probable Cause Approval Date: 05/17/2001
Aircraft: Bell 206B, registration: N5735A
Injuries: 1 Minor,2 Uninjured.

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 pilot of N5735A reported that he was transitioning the area of Lake Union (on a local electronic news gathering flight) in a south-southwesterly direction when the two aircraft collided. He stated that he simultaneously saw the other aircraft and felt the impact. After the collision, the pilot initiated a descent and landed on a nearby helipad. The pilot reported that prior to the collision he was monitoring the common traffic advisory frequency (CTAF) for Lake Union (122.90). He stated that just before transitioning the area he reported his position, altitude and heading on 122.90. The pilot of N206AC reported that he departed Boeing Field and was proceeding northbound. He stated that he had just cleared Boeing's Delta airspace and switched to Seattle Radio (122.50) when he '...experienced a loud bang and vibration in the main rotor system'. The pilot initiated a descent to a nearby helipad, and was able to land without further incident. The pilot stated he did not see the other aircraft before, or after the collision. There were no reported mechanical failures or malfunctions that may of contributed to the accident. A calculated convergence angle between the two aircraft indicated that there were no visual restrictions that would have prevented the pilot from seeing the other aircraft.

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

Adequate separation and lookout not maintained by the pilots of both aircraft.

Full narrative available

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