Cessna 170B accident near Big Lake, Alaska, September 23, 2020
On September 23, 2020 at about 3:00 am local time, a 1955 Cessna 170B, registered N4380B, was substantially damaged in an accident during landing near Big Lake, Alaska. It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot’s failure to utilize carburetor heat while flying in conditions conducive to carburetor icing, which resulted in a total loss of engine power.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 23, 2020 · about 3:00 am local time
- Place
- Big Lake, Alaska · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 170B, built 1955 · all 170Bs on the register
- Registration
- N4380B · registry record · serial 26724
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During a landing to a remote off-airport gravel bar located along a river, while at about 20 ft above ground level, the airplane’s engine lost power. The engine then surged briefly before a total loss of engine power occurred. Subsequently, the airplane landed short of the gravel bar in the river and the airplane nosed over. The airplane sustained substantial damage to the left wing and empennage. A postaccident examination revealed no mechanical failures or malfunctions. A postaccident engine run was successfully performed. A non-aviation fuel tank was installed on the top of the fuselage to provide a fuel source. Air was applied to the fuel lines to provide pressure to ensure proper fuel flow, no contaminates were noted in the fuel lines. The temperature and dew point were entered into a carburetor icing probability chart, which coincided with the “serious icing in glide power” category.
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
What happened, in order
- Nose over/nose down during landing (flare/touchdown)
- Landing area undershoot during landing
- Loss of engine power (total) during landing
- Fuel related during landing defining event
The NTSB's findings
- Personnel issues › Action/decision › Action › Lack of action › Pilot
- Aircraft › Aircraft systems › Ice/rain protection system › Intake anti › ice, deice › Not used/operated
- Environmental issues › Conditions/weather/phenomena › Temp/humidity/pressure › Conducive to carburetor icing › Contributed to outcome
Pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 8,839 hours in all; 297 in this make and model; 173 in the last 90 days; 68 in the last 30 days; 5,968 as pilot in command; 1,273 on instruments
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 3,295 hours
- Last inspection: annual inspection, May 31, 2020
- Maximum gross weight: 2,200 lb
- Seats: 4
- Landing gear: fixed
- Engine: Franklin PZL 6A-350-C2 (piston); 157 hours total
The flight
- Departed from: MRL Anchorage AK at 2:00 am
- Flight plan: VFR
Weather at the time
- Light: daylight
- Wind: from 040° at 9 knots, gusting 14
- Visibility: 10 statute miles
- Sky: overcast at 8,500 ft
- Temperature: 55°F (13°C), dew point 37°F (3°C)
- Altimeter: 29.31 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
6 documents, released by the NTSB on March 21, 2022. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Pilot Roc | PDF, 1 page | View Download |
| 3 | Salvage Company Roc | PDF, 1 page | View Download |
| 4 | Examination Notes | PDF, 3 pages | View Download |
| 5 | Carburetor Icing Probability Graph | PDF, 1 page | View Download |
| 6 | Accident Pictures | PDF, 4 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.