Friday, December 27, 2019

Unknown or Undetermined: Piper PA-12, N7511H; fatal accident occurred September 22, 2018 in Healy, Alaska

Timothy Mark Sonnenberg, age 45 and Jason Dean Roberts, age 43.

The National Transportation Safety Board traveled to the scene of this accident.

Additional Participating Entities:

Federal Aviation Administration / Flight Standards District Office; Fairbanks, Alaska
Lycoming Engines; Williamsport, Pennsylvania

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Healy, AK
Accident Number: ANC18FA071
Date & Time: 09/22/2018, 1600 AKD
Registration: N7511H
Aircraft: Piper PA-12-150
Aircraft Damage: Substantial
Defining Event: Unknown or undetermined
Injuries: 2 Fatal
Flight Conducted Under: Part 91: General Aviation - Personal

View of airplane from front.

On September 22, 2018, the wreckage of a tailwheel-equipped Piper PA-12 airplane, N7511H, was located in remote mountainous terrain about 35 miles east of Healy, Alaska. The private pilot and the passenger were fatally injured, and the airplane was substantially damaged by impact forces and a postcrash fire. The airplane was registered to the pilot who was operating it as a Title 14 Code of Federal Regulations Part 91 personal flight. The flight departed from Fairbanks International Airport (FAI), Fairbanks, Alaska, on September 15, 2018, and no flight plan had been filed.

The purpose of the flight was to fly to the Alaska Range, which is a mountain range located about 50 miles south of Fairbanks, where the pilot and his passenger would hunt sheep. No communications from the pilot, such as from a satellite phone or a satellite communication device, were received by the family after the pilot's departure from FAI.

After the pilot did not report to his place of employment on September 19, a Federal Aviation Administration (FAA) alert notice "ALNOT" was issued at 1620 Alaska daylight time, and an extensive search and rescue (SAR) operation began the next day. The operation consisted of aerial SAR assets from multiple agencies, including the Alaska Air National Guard, the Alaska Army National Guard, the Civil Air Patrol, and the Alaska State Troopers, as well as several individual volunteers. The accident airplane was located by a volunteer, and an Alaska Army National Guard helicopter responded to the accident site and the aircrew found both occupants deceased inside of the wreckage.

View of airplane from right rear.

Pilot Information

Certificate: Private
Age: 45, Male
Airplane Rating(s): Single-engine Land; Single-engine Sea
Seat Occupied:
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): None
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: Yes
Medical Certification: Class 3 With Waivers/Limitations
Last FAA Medical Exam: 01/16/2018
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time:  (Estimated) 128.8 hours (Total, all aircraft), 77.5 hours (Pilot In Command, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: Piper
Registration: N7511H
Model/Series: PA-12-150
Aircraft Category: Airplane
Year of Manufacture: 1946
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 12-372
Landing Gear Type: Tailwheel
Seats: 3
Date/Type of Last Inspection: 06/12/2018, Annual
Certified Max Gross Wt.: 1750 lbs
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time: 4141.4 Hours as of last inspection
Engine Manufacturer: Lycoming
ELT: Installed, not activated
Engine Model/Series: O-320-A2B
Registered Owner: On file
Rated Power: 150 hp
Operator: On file
Operating Certificate(s) Held: None

The airplane was equipped with a Garmin Aera GPS device, which was sent to the National Transportation Safety Board's (NTSB) Vehicle Recorder Division Laboratory in Washington, DC. The device is capable of storing data in nonvolatile memory. However, the circuit board was delaminated due to the thermal damage, and most of the components were burned off. The extent of the damage precluded recovery of the data.

The airplane was also equipped with an emergency locator transmitter (ELT), which did not broadcast after the accident. The ELT sustained postimpact fire damage, so the NTSB could not definitively determine why the ELT did not broadcast.

View of airplane from front left.

Meteorological Information and Flight Plan

Conditions at Accident Site: Unknown
Condition of Light: Not Reported
Observation Facility, Elevation: PAHV, 12944 ft msl
Distance from Accident Site: 33 Nautical Miles
Observation Time:
Direction from Accident Site: 267°
Lowest Cloud Condition:
Lowest Ceiling:
Visibility (RVR):
Wind Speed/Gusts:
Turbulence Type Forecast/Actual:
Wind Direction:
Turbulence Severity Forecast/Actual:
Altimeter Setting:
Temperature/Dew Point:
Precipitation and Obscuration:
Departure Point: Fairbanks, AK (FAI)
Type of Flight Plan Filed: None
Type of Clearance: Unknown
Departure Time:  AKD
Type of Airspace: Class G

The exact meteorological conditions before and at the time of the accident could not be determined.

Wreckage and Impact Information

Crew Injuries: 1 Fatal
Aircraft Damage: Substantial
Passenger Injuries: 1 Fatal
Aircraft Fire: Fire At Unknown Time
Ground Injuries: N/A
Aircraft Explosion: Unknown
Total Injuries: 2 Fatal
Latitude, Longitude: 63.900278, -147.733333 

The wreckage of the airplane was located in a remote snow-covered mountainous valley with rocks, alder trees, and a small creek. The wreckage was positioned on the east side of the creek on a heading of about 220° and at an elevation of about 4,300 ft mean sea level. Most of the wreckage showed evidence of a postimpact fire. The airplane came to rest upright, with the fuselage banking to the right, both wings indicating forward/aft crushing, and the tail slightly elevated with little impact damage.

All of the major structural components of the airframe were located at the accident site. An examination of the airframe revealed no pre-impact mechanical malfunctions or failures that would have precluded normal operation.

The engine was examined after the recovery of the wreckage. The examination revealed no pre-impact mechanical malfunctions or failures that would have precluded normal operation.

During examination, the AFT right wing spar exhibited signs of compression bending, with the right wing forward spar exhibiting aft bending. The AFT left wing spar bolt indicated a failure in tension, and the left wing forward spar indicated forward bending.

Medical And Pathological Information

The State of Alaska Medical Examiner's Office, Anchorage, Alaska, conducted an autopsy of the pilot. According to the autopsy report, the cause of death for the pilot was multiple blunt force injuries. The report also indicated that there was no evidence of soot-like material found in the pilot's airway.

Toxicology testing performed at the FAA Forensic Sciences Laboratory found that the pilot's specimens were negative for drugs and ethanol. 

Additional Information

Search and Rescue

The FAA's Aeronautical Information Manual (AIM) discusses SAR operations and states in part the following: SAR is a lifesaving service provided through the combined efforts of the federal agencies' signatory to the National SAR Plan, and the agencies responsible for SAR within each state. Operational resources are provided by the U.S. Coast Guard, DOD [Department of Defense] components, the Civil Air Patrol, the Coast Guard Auxiliary, state, county and local law enforcement and other public safety agencies, and private volunteer organizations. Services include search for missing aircraft, survival aid, rescue, and emergency medical help for the occupants after an accident site is located.

Flight Plan

The AIM discusses the importance of filing a flight plan in case of an emergency or if an aircraft is overdue and states in part the following:

A filed flight plan is the most timely and effective indicator that an aircraft is overdue. Flight plan information is invaluable to SAR forces for search planning and executing search efforts.

Prior to departure on every flight, local or otherwise, someone at the departure point should be advised of your destination and the route of flight if other than direct. Search efforts are often wasted, and rescue is often delayed because of pilots who thoughtlessly take off without telling anyone where they are going. File a flight plan for your safety.


  1. Not that this had anything to do with it ...

    If asked I'm sure the owner would have said that the plane was really well maintained ... Hey, I just put a new engine in it!


  2. Low time pilot with no instrument rating going into challenging terrain in the middle of nowhere in a state where roads are quasi-nonexistent without telling anyone where they will go and not filing a flight plan.
    What can possibly go wrong?