Air Tractor INC AT 502B accident near Harrold, South Dakota, July 26, 2017
On July 26, 2017 at about 8:30 pm local time, a 2009 Air Tractor INC AT 502B, registered N421CA, was substantially damaged in an accident during maneuvering (low-alt flying) near Harrold, South Dakota. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 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 improper attempt at a low-pass maneuver, which resulted in a collision with a tractor.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 26, 2017 · about 8:30 pm local time
- Place
- Harrold, South Dakota · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor INC AT 502B B, built 2009 · all AT 502Bs on the register
- Registration
- N421CA · registry record · serial 502B-2672
- 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 of an agricultural airplane reported that he planned to apply an herbicide and test the spray system at maximum pressure at a specified airspeed. He added that a ground tractor was also in the field applying the same chemical. During the flight, he saw the tractor and passed over it between about 50 and 100 ft above ground level (agl). While spraying at 10 ft agl, he noted pressure, output, airspeed, and ground speed. At the end of the field, he climbed and made a left, 180° turn for another pass. The pilot reported that he "lost focus" outside of the airplane while looking at the spray results, and when he noticed the tractor, it was too late; the airplane's wheel collided with the tractor. Examination of the airplane revealed substantial damage to the fuselage. The tractor driver reported that he heard someone call him on the radio and that he answered the pilot on the radio and saw the airplane coming "directly at him, very low." The tractor driver heard and felt the impact and was knocked from his seat by the collision. The tractor driver then called his supervisor for help. The tractor driver added that his supervisor and another ground sprayer had been "buzzed" by the pilot before.
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
- Collision with terrain or object (not controlled flight into terrain) during maneuvering (low-alt flying)
- Miscellaneous/other during maneuvering (low-alt flying) defining event
The NTSB's findings
- cause Environmental issues › Physical environment › Object/animal/substance › Ground vehicle › Effect on operation
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Altitude › Not attained/maintained
- cause Personnel issues › Miscellaneous › Intentional act › (general) › Pilot
- cause Personnel issues › Action/decision › Action › Incorrect action selection › Pilot
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: sngl
- Injury: no injuries
The aircraft
- Last inspection: inspection type not recorded
- Landing gear: fixed
- Operator: Custom Air INC
The flight
- Departed from: Harrold SD
- Destination: Harrold SD
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 040° at 10 knots, gusting 17
- Visibility: 10 statute miles
- Temperature: 90°F (32°C), dew point 52°F (11°C)
- Altimeter: 30.06 inHg
- Observation at 8:53 pm from KPIR, 40 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
3 documents, released by the NTSB on November 9, 2017. 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 | Tractor Operator Statement | PDF, 1 page | View Download |
| 2 | Memo | PDF, 1 page | View Download |
| 3 | Flightpath | PDF, 3 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.