Bell 206L-3 and Bell 206B mid-air collision near Seattle, Washington, November 17, 1999
On November 17, 1999 at about 8:10 pm local time, 2 aircraft, Bell 206L-3 (N206AC) and Bell 206B (N5735A), were involved in a mid-air collision near Seattle, Washington. 1 person had minor injuries; 2 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Adequate separation and lookout not maintained by the pilots of both aircraft.
Adequate separation and lookout not maintained by the pilots of both aircraft.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 17, 1999 · about 8:10 pm local time
- Place
- Seattle, Washington · map
- Type
- Accident · mid-air collision
- Injuries
- 1 person had minor injuries; 2 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft 1
- Bell 206L-3 · all 206L-3s on the register
- Registration
- N206AC · registry record · serial 51545
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
- Aircraft 2
- Bell 206B · all 206Bs on the register
- Registration
- N5735A · no longer on the register · serial 3002
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative for the Bell 206L-3 final · quoted from the NTSB record
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 complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The NTSB's narrative for the Bell 206B final · quoted from the NTSB record
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 complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record for the Bell 206L-3 from the NTSB's investigation tables, in plain English
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: airplane single-engine; instructor: helicopter; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 19,000 hours in all; 14,000 in this make and model; 200 in the last 90 days; 85 in the last 30 days; 18,750 as pilot in command; 1,500 on instruments
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 1,698 hours
- Last inspection: annual inspection, November 17, 1999; 1 hours since
- Maximum gross weight: 4,150 lb
- Seats: 7
- Landing gear: fixed
- Engine: Allison 250-C30P (turboshaft); 0 hours total
The flight
- Departed from: BFI Seattle WA at 8:05 pm
- Destination: YVR Vancouver
- Flight plan: VFR
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 360° at 4 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 1,700 ft; not recorded
- Temperature: 52°F (11°C), dew point 45°F (7°C)
- Altimeter: 29.00 inHg
- Observation at 7:53 pm from BFI, 7 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
The factual record for the Bell 206B from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 12,500 hours in all; 10,000 in this make and model; 12,300 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 10,969 hours
- Last inspection: 100-hour inspection, October 16, 1999; 76 hours since
- Maximum gross weight: 3,200 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20B (turboshaft); 0 hours total
- Operator: Kiro INC.
The flight
- Departed from: BFI Seattle WA at 7:30 pm
- Flight plan: none
- Runway 0
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.