Keith Walker
July 02, 1946 - March 06, 2021
~
The National Transportation Safety Board did not travel to the scene of this accident.
Additional Participating Entities:
Federal Aviation Administration / Flight Standards District Office; Lincoln, Nebraska
Lycoming; Williamsport, Pennsylvania
Investigation Docket - National Transportation Safety Board:
Location: Berwyn, Nebraska
Accident Number: CEN21FA150
Date and Time: March 6, 2021, 06:10 Local Registration: N166WW
Aircraft: Aviat A-1B
Aircraft Damage: Destroyed
Defining Event: Loss of visual reference
Injuries: 1 Fatal
Flight Conducted Under: Part 91: General aviation - Personal
On March 6, 2021, about 0610 central standard time, an Aviat A-1B airplane, N166WW, was destroyed when it was involved in an accident near Berwyn, Nebraska. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight.
The purpose of the flight was to fly from the pilot’s private runway to Holyoke, Colorado for an annual inspection. About 0555, primary radar first picked up the airplane about 1/2 mile south of the private runway. The airplane track proceeded generally west-southwest for about 11 miles when it made a left turn toward the south at a speed of about 88 knots. The track then made right 360-degree turn; during which, the speed of the airplane increased to about 114 knots. Followed by a tighter 360-degree turn at 49 knots and decreasing. The track then zig zagged at an average of 30 knots until 0609 when the track terminated about 1,000 ft from the accident site.
A GPS was recovered from the accident site; however, the unit and memory card exhibited extensive impact damage and data was unable to be extracted.
Pilot Information
Certificate: Private
Age: 74, Male
Airplane Rating(s): Single-engine land
Seat Occupied: Unknown
Other Aircraft Rating(s): None
Restraint Used: 4-point
Instrument Rating(s): None
Second Pilot Present:
Instructor Rating(s): None
Toxicology Performed: Yes
Medical Certification: BasicMed With waivers/limitations
Last FAA Medical Exam: June 26, 2020
Occupational Pilot: UNK
Last Flight Review or Equivalent:
Flight Time: (Estimated) 2395 hours (Total, all aircraft), 2395 hours (Total, this make and model)
The pilot was issued a private pilot certificate on May 26, 1969. The pilot flew the accident airplane regularly over his land and pastures; and was used to maneuvering at low altitudes. It was not abnormal for him to takeoff before sunrise, especially if he needed to get somewhere and return in the same day.
Aircraft and Owner/Operator Information
Aircraft Make: Aviat
Registration: N166WW
Model/Series: A-1B
Aircraft Category: Airplane
Year of Manufacture: 2006
Amateur Built:
Airworthiness Certificate: Normal
Serial Number: 2372
Landing Gear Type: Tailwheel
Seats:
Date/Type of Last Inspection: Unknown
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time:
Engine Manufacturer: Lycoming
ELT: Installed, not activated
Engine Model/Series: IO-360-A1D6
Registered Owner:
Rated Power: 200 Horsepower
Operator: On file
Operating Certificate(s) Held: None
Meteorological Information and Flight Plan
Conditions at Accident Site: Visual (VMC)
Condition of Light: Night
Observation Facility, Elevation: BBW, 2546 ft msl
Distance from Accident Site: 13 Nautical Miles
Observation Time: 05:53 Local
Direction from Accident Site: 325°
Lowest Cloud Condition: Clear
Visibility 10 miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: /
Turbulence Type Forecast/Actual: None / None
Wind Direction:
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 30.15 inches Hg
Temperature/Dew Point: -1°C / -2°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Mason City, NE (PVT)
Type of Flight Plan Filed: None
Destination: Holyoke, CO (HEQ)
Type of Clearance: Unknown
Departure Time: 05:55 Local
Type of Airspace:
At the time of the accident the moon was 22.97 degrees above the horizon in third quarter phase. Its illumination was 45.1% of the moon’s full potential. There were no high-altitude cloud layers. Dawn started at 0636 and sunrise was at 0704.
Wreckage and Impact Information
Crew Injuries: 1 Fatal
Aircraft Damage: Destroyed
Passenger Injuries:
Aircraft Fire: On-ground
Ground Injuries:
Aircraft Explosion: None
Total Injuries: 1 Fatal
Latitude, Longitude: 41.1965,-99.4836
The airplane impacted a field perpendicular to a gully in a very rural area; the debris field was about 300 ft long. The first identified point of impact was a long narrow area of disturbed dirt with the right wingtip nearby. Next were two slash marks consistent with propeller blade slices; followed by a large area of disturbed dirt with propeller blade fragments. The main wreckage came to rest at the bottom of the gully; the last major piece of debris was the engine.
The airframe came to rest in a ball and exhibited extensive thermal damage. The fabric was completely gone and only the frame remained. Flight control continuity was mostly established throughout the airframe. The rudder controls were untraceable within the cockpit area; they were in an area of melted material. Both composite propeller blades were fracture separated at the blade root, and one blade was also fractured midspan. Both blades exhibited chordwise scratching on the face and chamber sides.
The engine was found fracture separated from the airframe; it exhibited extensive thermal damage and there were no visual signs of catastrophic anomalies. The firewall was removed, and the engine was attached to an engine hoist for further examination. The spark plugs were removed and consistent with normal operations. The fuel flow divider was disassembled, and fuel residue was present. The fuel servo remained attached, but the engine controls were fracture separated consistent with impact damage. The valve covers were removed, and the valves were unremarkable. The crankshaft was rotated by the propeller hub and continuity was established to the accessory section. Thumb compression was established on all cylinders and the valves moved accordingly. The engine was borescoped; the cylinder walls, piston heads, and valves displayed normal operating signatures. Spark was obtained on the right magneto; the left magneto was unable to be rotated and exhibited heavy thermal damage. The ignition harness was unable to be functionally tested due to damage consistent with impact.
Medical and Pathological Information
The Federal Aviation Administration (FAA) Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the pilot with positive results for Diltiazem and Warfarin in the liver and muscle.
Diltiazem is a prescription blood pressure medication that may also be used to treat fast heart rates associated with atrial fibrillation, an abnormal heart rhythm. Warfarin is a blood thinner used to prevent blood clots in patients with previous ischemic stroke, atrial fibrillation, or other forms of blood clots. Neither are generally considered impairing.
7 miles into 160 mile distance from Mason, NB to Holyoke, CO (HEQ)
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