Sonex Aircraft SONEX accident near River Falls, Wisconsin, July 29, 2022
On July 29, 2022 at about 11:52 am local time, a 2020 Sonex Aircraft SONEX, an amateur-built aircraft,, registered N1557S, was substantially damaged in an accident during enroute near River Falls, Wisconsin. It was a flight test under general aviation rules (Part 91). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot’s improper fuel planning, which resulted in a total loss of engine power due to fuel exhaustion.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 29, 2022 · about 11:52 am local time
- Place
- River Falls, Wisconsin · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Sonex Aircraft SONEX UNDESIGNAT, built 2020, amateur-built
- Registration
- N1557S · no longer on the register · serial 1557
- Damage
- Substantial damage
- Flight
- Flight test · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot completed the preflight inspection with no issues noted; the airplane had about 10.3 gallons of fuel onboard for the local flight test. The airplane departed and, after flying for between 30 and 45 minutes, the pilot decided to return to the airport. Shortly thereafter, the engine sustained a total loss of power. The pilot reported that the engine did not emit any noises, nor did he notice a drop in the engine’s rpm. The pilot tried restarting the engine three times. Although the engine would “turn over,” it would not start. The pilot elected to perform a forced landing to a corn field. During the landing, the right wing impacted a traffic sign and the airplane came to rest upright in a grass ditch. The airplane sustained substantial damage to the right wing and the fuselage. The on-site examination of the airplane found no fuel inside of the fuel tank; the fuel tank was not compromised. There were no signs of a fuel leak on the airframe or from the engine, nor were there any signs of a fuel leak or spillage on the ground at the accident site. During a postaccident examination, the fuel line to the carburetor was removed and no fuel was observed. No fuel was observed from the fuel supply line to the strainer. The bowl from the strainer was removed and no fuel was found. There were no preimpact mechanical malfunctions or failures with the airframe or the engine that would have precluded normal operation. Based on the available evidence, it is likely that the engine lost power due to fuel exhaustion.
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
- Preflight or dispatch event during prior to flight
- Attempted remediation/recovery during enroute
- Off-field or emergency landing during landing
- Collision during takeoff/land during landing
- Fuel exhaustion during enroute defining event
The NTSB's findings
- Personnel issues › Task performance › Planning/preparation › Fuel planning › Pilot
- Aircraft › Fluids/misc hardware › Fluids › Fuel › Fluid level
- Aircraft › Aircraft power plant › Engine (reciprocating) › (general) › Failure
- Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 200 hours in all; 15.5 in this make and model; 5.5 in the last 90 days; 5.5 in the last 30 days; 200 as pilot in command
- Last flight review: September 11, 2020
- Medical certificate: BasicMed (with waivers/limitations)
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 18.6 hours
- Last inspection: annual inspection, October 14, 2021; 18.6 hours since
- Maximum gross weight: 1,100 lb
- Seats: 2
- Landing gear: fixed
- Engine: Revmaster R-2300 (piston); 18 hours total
The flight
- Departed from: SGS South St. Paul MN at 11:10 am
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 340° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 61°F (16°C), dew point 55°F (13°C)
- Altimeter: 30.06 inHg
- Observation at 6:55 am from KSGS, 17 miles away
Weather report (METAR): KSGS 291155Z AUTO 34005KT 10SM CLR 16/13 A3006 RMK AO2 T01610132 10182 20150
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
7 documents, released by the NTSB on January 31, 2024. 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 | Accident Photographs | PDF, 10 pages | View Download |
| 3 | FAA Aviation Safety Inspector - Statement | PDF, 1 page | View Download |
| 4 | FAA Aviation Safety Inspector - Examination Report N1557S | PDF, 1 page | View Download |
| 5 | Engine Data Monitor - Specialist Factual Report | PDF, 7 pages | View Download |
| 6 | Engine Data Monitor - Specialist Factual Report - Attachment 1 | data file | Download |
| 7 | Release of Aircraft Wreckage, NTSB Form 6120.15 | PDF, 2 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.
