WPR21LA299 · Schweizer Aircraft Corp G-164B
Haley's Flying Service Schweizer Aircraft Corp G-164B · Accident during an emergency descent
From Tracy, CA to Tracy, CA
Event
- NTSB case
- WPR21LA299
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- Event fatalities
- Unknown
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Schweizer Aircraft Corp G-164B
- Aircraft type
- Schweizer G-164
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N3629F
- Operator
- Haley's Flying Service
- Onboard fatalities
- Unknown
- Route
- From Tracy, CATo Tracy, CA
- Aircraft age
- About 37 years (built 1984)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 137: Agricultural
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Emergency descent
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Unknown or undetermined
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft power plant
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that he was performing a low-level agricultural pesticide application on a hay field when the engine suddenly lost all power. Although the airplane was at a high airspeed at the time, the pilot was unable to climb due to the presence of high-tension powerlines above him in his flightpath. During the subsequent descent, he flew beneath a set of powerlines, turned, and landed in a field after his airspeed had decreased. During the landing, the airplane contacted the ground and trees, which resulted in substantial damage to the fuselage and wings. Postaccident examination of the engine and accessories did not reveal any mechanical anomalies that could have precluded normal operation. Evidence of rotational scoring and metal spray deposits in the engine indicate that it was operating at the time of impact. The fuel solenoid shutoff valve was in the CLOSED position, which would have prevented fuel flow to the engine. However, due to the overwhelming evidence that the engine was rotating at the time of impact, it is likely that the shutoff valve moved to the CLOSED position as a result of the impact. Propeller signatures indicated that the blades impacted the ground while rotating at low power. An examination of the propeller did not reveal any visible discrepancies that would have affected performance prior to impact. The damage to the start lock brackets, start lock plates, and a contact mark on the internal surface of the piston suggest the propeller was on or below the start lock angle at impact. This was likely the result of impact forces, as the pilot stated that he did not reduce throttle input or attempt to feather blades before impact. Previous maintenance indicated that the blade radius was properly set. The pilot did not recall the power lever position at the time of the power loss and the investigation did not reveal any evidence of preimpact mechanical malfunctions or failures. Therefore, the reason for the pilot’s reported loss of power could not be determined.
Probable cause
A loss of thrust during a low-level agricultural application flight, which resulted in a descent and impact with terrain. The reason for the loss of thrust could not be determined based on available information.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR21LA299
- Event ID
- 20210731103594
- Case number
- WPR21LA299
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: b3bdc5c6e72bfe8a07c675932543ac72131f6e69d2388eebbc8a2d7ca47b0547; retrieved 2026-09-16T14:21:20.998Z.