Brantly Helicopter B-2B accident near Novato, California, September 12, 1990
On September 12, 1990 at about 11:03 pm local time, a Brantly Helicopter B-2B, registered N2159W, was substantially damaged in an accident near Novato, California (Gnoss airport). It was an instructional flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE PILOT'S IMPROPER EXECUTION OF THE AUTOROTATION. CONTRIBUTING TO THIS ACCIDENT WAS THE EXCESSIVE SINK RATE AND MISJUDGING OF THE ALTITUDE.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 12, 1990 · about 11:03 pm local time
- Place
- Novato, California · Gnoss · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Brantly Helicopter B-2B
- Registration
- N2159W · no longer on the register · serial 320
- Damage
- Substantial damage
- Flight
- Instructional flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
WHILE ON AN ADDED RATING FLIGHT TEST THE FAA DESIGNATED EXAMINER CALLED FOR A SIMULATED ENG FAILURE. THE PRIVATE PILOT APPLICANT IMMEDIATELY LOWERED THE COLLECTIVE AND BEGAN A 180 DEGREE TURN INTO THE WIND. WHEN THE HELICOPTER WAS ABOUT 160 DEGREES INTO THE TURN AND WAS ABOUT 50 FEET ABOVE THE GROUND THE PILOT BEGAN THE POWER RECOVERY BUT DUE TO THE HIGH SINK RATE THE SKIDS STRUCK THE SOFT DIRT OF A FRESHLY PLOWED FIELD CAUSING THE HELICOPTER TO ROLL TO THE RIGHT AND THE MAIN ROTOR BLADES TO STRIKE THE GROUND.
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 from the NTSB's investigation tables, in plain English
Pilot
- Certificate: private
- Ratings: rotorcraft: helicopter
- Flight time: 338 hours in all; 61 in this make and model; 15 in the last 90 days; 7 in the last 30 days; 234 as pilot in command
- Medical certificate: Class 3
- Seat: rgt
The aircraft
- Last inspection: inspection type not recorded; 0 hours since
- Maximum gross weight: 1,670 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming IVO-360-A1A (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 270° at 15 knots
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 |
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.