Grumman G164 accident near Hays, Kansas, August 20, 2019
On August 20, 2019 at about 2:15 pm local time, a 1985 Grumman G164, registered N3631Z, was destroyed in an accident during maneuvering (low-alt flying) near Hays, Kansas (Werth Private Airstrip airport). It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's exceedance of the airplane's critical angle of attack, which resulted in an aerodynamic stall.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 20, 2019 · about 2:15 pm local time
- Place
- Hays, Kansas · Werth Private Airstrip · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman G164 B, built 1985 · all G164s on the register
- Registration
- N3631Z · no longer on the register · serial 765B
- Damage
- Destroyed
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The pilot was performing an agricultural application flight, and the airplane was observed departing a private airstrip to the east toward a field west of the airstrip. The airplane impacted terrain in a steep, nose-down attitude. A postimpact fire ensued. There were no witnesses to the accident. Impact signatures and twisting of the wreckage were indicative of a nose-low spin, consistent with an aerodynamic stall . Flight control continuity could not be verified due to fire damage, but no anomalies were noted with the airframe and engine that would have precluded normal operation. The pilot's toxicology tests results showed no drug or alcohol use. Thus, it is likely that aerodynamic stall resulted from the pilot allowing the airplane to exceed its critical angle of attack during a turn.
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
- Aerodynamic stall/spin during maneuvering (low-alt flying) defining event
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
- Fire/smoke (post-impact) during post (impact)
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Angle of attack › Not attained/maintained
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Airspeed › Not attained/maintained
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 18,616 hours in all
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: sngl
- Injury: fatal
The aircraft
- Airframe total time: 2,616 hours
- Last inspection: annual inspection, April 6, 2019
- Seats: 1
- Landing gear: fixed
- Engine: Pratt And Whitney R-985-AN-14B (piston); 0 hours total
- Fire on the ground
- Operator: Werth Aerial Spraying Inc
The flight
- Departed from: Hays KS at 2:13 pm
- Destination: Hays KS
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 200° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 79°F (26°C), dew point 70°F (21°C)
- Altimeter: 29.92 inHg
- Observation at 1:56 pm from KHYS, 9 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
9 documents, released by the NTSB on March 25, 2020. 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 | Record of Conversation - Pilot's Wife | PDF, 1 page | View Download |
| 2 | Engine Examination Report | PDF, 12 pages | View Download |
| 3 | Maintenance Records | PDF, 6 pages | View Download |
| 4 | Toxicological Report | PDF, 1 page | View Download |
| 5 | Statement of Party Representatives to NTSB Investigation | PDF, 1 page | View Download |
| 6 | Maps or Charts of Accident Area | PDF, 1 page | View Download |
| 7 | Release of Aircraft Wreckage, NTSB Form 6120.15 | PDF, 2 pages | View Download |
| 8 | Propeller Email | PDF, 2 pages | View Download |
| 9 | Photos | PDF, 7 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.