Air Tractor, Inc. AT-400 accident near Monango, North Dakota, August 23, 2011
On August 23, 2011 at about 11:53 pm local time, a Air Tractor, Inc. AT-400, registered N23720, was substantially damaged in an accident during maneuvering (low-alt flying) near Monango, North Dakota. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot did not maintain adequate separation from a tree during the aerial-application flight.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 23, 2011 · about 11:53 pm local time
- Place
- Monango, North Dakota · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor, Inc. AT-400
- Registration
- N23720 · no longer on the register · serial 400-0422
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that he remembered completing a majority of his spray runs during the aerial-application flight and was finishing along the field's edge when the accident occurred. However, he had no recollection of the airplane colliding with the trees or terrain. Global positioning system data revealed that the airplane had descended from about 300 feet above ground level (agl) to less than 100 feet agl into a sparsely wooded area during the last 15 seconds of the flight. A postaccident examination established that the airplane's right wingtip contacted a tree before the airplane collided with terrain. The examination did not reveal any mechanical malfunctions or failures that would have precluded normal operation of the airplane. The presence of fuel throughout the engine's fuel system and the rotational damage sustained by several engine components was consistent with a sudden stoppage of an operating engine during impact.
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
- Low altitude operation/event during maneuvering (low-alt flying) defining event
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Altitude › Not attained/maintained
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Environmental issues › Physical environment › Object/animal/substance › Tree(s) › Contributed to outcome
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 3,645 hours in all; 1,051 in this make and model; 175 in the last 90 days; 50 in the last 30 days; 3,645 as pilot in command
- Last flight review: January 27, 2010
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: ctr
- Injury: serious injuries
The aircraft
- Airframe total time: 9,354 hours
- Last inspection: annual inspection, July 29, 2011
- Maximum gross weight: 7,600 lb
- Seats: 1
- Landing gear: fixed
- Engine: Pratt & Whitney PT6A-15AG (turboprop); 0 hours total
- Operator: D-Lux Spray Service, LLC
The flight
- Departed from: 51D Edgeley ND at 11:19 pm
- Destination: 51D Edgeley ND
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 210° at 9 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 86°F (30°C), dew point 77°F (25°C)
- Altimeter: 29.61 inHg
- Observation at 11:55 pm from KGWR, 36 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 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.
Other NTSB records under N23720 the same tail number, which may have belonged to a different aircraft at the time
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.