Grumman G 164 accident near Marydel, Delaware, July 19, 2017
On July 19, 2017 at about 1:21 pm local time, a 1964 Grumman G 164, registered N691Y, was substantially damaged in an accident during maneuvering near Marydel, Delaware. 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's failure to maintain adequate clearance from power lines while conducting an aerial application flight.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 19, 2017 · about 1:21 pm local time
- Place
- Marydel, Delaware · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman G 164 UNDESIGNAT, built 1964 · all G 164s on the register
- Registration
- N691Y · no longer on the register · serial 242
- 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 commercial pilot was performing an aerial application flight. He had just completed his first pass spraying a field when the airplane struck a set of power lines and impacted a field adjacent to the field that he was spraying, which resulted in substantial damage to the fuselage and both wings. The pilot stated that he had no memory of the accident. Review of data downloaded from an onboard GPS unit was consistent with the airplane operating normally as it made a pass over the field and then initiating a climb near the power lines. The recorded data ended shortly after the airplane was on the opposite side of the power lines.
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 defining event
- Collision with terrain or object (not controlled flight into terrain) during maneuvering (low-alt flying)
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Personnel issues › Psychological › Attention/monitoring › Monitoring environment › Pilot
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Altitude › Not attained/maintained
- cause Environmental issues › Physical environment › Object/animal/substance › Tower/antenna (incl guy wires) › Effect on equipment
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 913 hours in all; 63 in this make and model
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: ctr
- Injury: serious injuries
The aircraft
- Airframe total time: 9,490.1 hours
- Last inspection: annual inspection, August 2, 2016
- Seats: 1
- Landing gear: fixed
- Engine: Pratt&Whitney R-985 (piston); 8,892 hours total
The flight
- Departed from: DE09 Magnolia DE at 1:10 pm
- Destination: None Marydel DE
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 200° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 81°F (27°C)
- Altimeter: 30.05 inHg
- Observation at 1:58 pm from DOV, 10 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
8 documents, released by the NTSB on December 12, 2018. 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 | Excerpt of FAA Inspector's Interview with the Pilot | PDF, 1 page | View Download |
| 3 | Maintenance Records | PDF, 2 pages | View Download |
| 4 | Toxicological Report | PDF, 1 page | View Download |
| 5 | Photos | PDF, 3 pages | View Download |
| 6 | Global Positioning System (GPS) Device - Factual Report | PDF, 7 pages | View Download |
| 7 | Attachment 1 to Global Positioning System (GPS) Device - Factual Report | data file | Download |
| 8 | Evidence Control Form | PDF, 1 page | 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.