# NTSB ANC20LA050: Rockwell 500, N909AK, Aniak, AK, May 29, 2020

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Class 3 · Limited · Final report
- Date: May 28, 2020, 16:00 local (May 29, 2020, 00:00 UTC)
- Place: Aniak, AK
- Coordinates: 61.581665, -159.54306 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=61.5817&lon=-159.5431&mi=10
- Phase of flight: [Prior to flight](https://openairdocs.org/ntsb-phases/100) (OpenAirDocs' grouping)
- Defining event: [Prior to flight: Wrong fuel](https://openairdocs.org/ntsb-events/194)
- Highest injury: Serious injuries
- Injuries: 4 serious
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Alaska Regional Office
- Parties: Federal Aviation Administration
- NTSB case key (mKey): 101338
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC20LA050
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101338/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101338
- Page: https://openairdocs.org/ntsb/ANC20LA050

## Probable cause

A loss of engine power due to the use of improper fuel. Contributing to the accident was the failure of the pilot and ground personnel to ensure that the airplane was serviced with the proper fuel.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Fluids: fuel](https://openairdocs.org/ntsb-findings/01071010): Aircraft › Fluids/misc hardware · Fluid type (probable cause); cases with it: [Aero Commander 500 S, 3 cases](https://openairdocs.org/ntsb-findings/01071010/cases.md?model=0141107), [All aircraft, 1,695 cases](https://openairdocs.org/ntsb-findings/01071010/cases.md)
- [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Ground crew (probable cause); cases with it: [Aero Commander 500 S, 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=0141107), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md)
- [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Aero Commander 500 S, 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=0141107), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Prior to flight: Wrong fuel](https://openairdocs.org/ntsb-events/194) (defining event); cases with it: [Aero Commander 500 S, 1 case](https://openairdocs.org/ntsb-events/194/sequence.md?model=0141107), [All aircraft, 9 cases](https://openairdocs.org/ntsb-events/194/sequence.md)
- [Takeoff: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Aero Commander 500 S, 4 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0141107), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)

## Analysis

After landing at the airport, the pilot had ground service personnel refuel the airplane. According to the fueler, he queried the pilot if he wanted Prist with his jet fuel, which the pilot replied, “No.” After completing the refueling process, he returned to his truck, wrote "Jet A" in the meter readings section of the prepared receipt, and presented it to the pilot for his signature. The pilot said that shortly after takeoff, he noticed a reduction in climb performance, and the airplane's engines began to lose power. Unable to maintain altitude, he selected an area of shallow water-covered terrain as a forced landing site. During the landing, the airplane sustained substantial damage. A postaccident examination revealed that the airplane, which was equipped with reciprocating engines, had been inadvertently serviced with Jet A turbine fuel. A slightly degraded placard near the fuel port on the top of the wing stated, in part: "FUEL 100/100LL MINIMUM GRADE AVIATION GASOLINE ONLY CAPACITY 159.6 US GALLONS." In an interview, the fueler who serviced the airplane stated that he did not see a fuel placard near the fueling port.

## Factual narrative

On May 28, 2020, about 1600 Alaska daylight time, an Aero Commander 500S airplane, N909AK sustained substantial damage when it was involved in an accident near Aniak, Alaska. The pilot and three passengers sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 public aircraft flight. The airplane was owned by the State of Alaska and operated by the Division of Forestry. According to the pilot, after arriving in Aniak, he had the local fuel vendor's ground service personnel refuel the airplane. He then signed the fuel receipt, and he returned to the airplane's cockpit to complete some paperwork before departure. Once the paperwork was complete, he then loaded his passengers, started the airplane's engines, and taxied to Runway 29 for departure. The pilot said that shortly after takeoff, and during initial climb, he initially noticed what he thought was mechanical turbulence followed by a reduction in climb performance, and the airplane's engines began to lose power. Unable to maintain altitude and while descending about 400 ft per minute, he selected an area of shallow water covered terrain as an off-airport landing site. The airplane sustained substantial damage during the landing. The fueler reported that he was unfamiliar with the airplane, so he queried the pilot as to where he should attach the grounding strap and the location of the fuel filler port. Before starting to refuel the airplane, he asked the pilot "do you want Prist with your Jet" to which the pilot responded that he did not. After completing the refueling process, he returned to his truck, wrote "Jet A" in the meter readings section of the prepared receipt, and presented it to the pilot for his signature. The pilot signed the receipt and was provided a copy. The fueler stated that he later added "no Prist" to his copy of the receipt, and that he did not see a fuel placard near the fueling port. A postaccident examination revealed that the reciprocating engine airplane had been inadvertently serviced with Jet A fuel. A slightly degraded placard near the fuel port on the top of the wing stated, in part: "FUEL 100/100LL MINIMUM GRADE AVIATION GASOLINE ONLY CAPACITY 159.6 US GALLONS." (see Figure 1.) Figure 1 - Fuel placard on accident airplane located near fueling port.

## Aircraft

- Registration: [N909AK](https://openairdocs.org/deregistered/N909AK-2023-01-12), registration cancelled 2023-01-12, S/N 3232, built 1975 (OpenAirDocs)
- Reported make and model: Rockwell 500 (S)
- Registry model: [Aero Commander 500 S](https://openairdocs.org/model/aero-commander-500-s) (registry code 0141107) (OpenAirDocs)
- Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 3232
- Year built: 1975
- Airframe hours: 6966.4
- Engines: Lycoming IO-540 SER 325 horsepower reciprocating; Lycoming IO-540 SER 325 horsepower reciprocating
- Damage: Substantial damage
- Flight: Public aircraft - state, Public use
- Operator: State Of Alaska
- Registered owner: State Of Alaska
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, March 5, 2020
- Departed: Aniak, AK
- Destination: Soldotna, AK
- Flight plan: Company VFR
- Equipment: Electronic primary flight display, Electronic multifunction display, Auto-pilot, ADS-B, Stall warning system, Satellite tracking device

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 53; injuries: serious; flight instructor, airline transport, commercial; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; seat: left; flight hours: 4,869 total, 30 in this make and model, 4,003 as pilot in command, 40 in the last 90 days, 40 in the last 30 days, 4.5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: 12,000 ft overcast
- Temperature: 59 °F, dew point 36 °F
- Altimeter: 30.15 inHg

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20200528011569A](https://openairdocs.org/incident/20200528011569A), May 28, 2020: Aero Commander 500 S, Aniak, AK, Substantial damage. Aircraft stop for refueling, and pilot On 28 may 2020, around 1600 Alaska time, an Aero Commander airplane, N909AK sustained substantial damage when it was…

## Docket (5 files)

The files NTSB released with the investigation on November 12, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101338. 4.4 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9931509&FileExtension=pdf&FileName=NTSB%206120%20DMS%20Redacted-Rel.pdf
- Witness statements (item 2, PDF, 60 pages, 117 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9998317&FileExtension=pdf&FileName=ANC20LA050%20Interviews%20DMS_Redacted-Rel.pdf
- Fuel delivery ticket (item 3, PDF, 1 page, 656 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12826298&FileExtension=pdf&FileName=Delivery%20Ticket%2031633_Redacted-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 4, PDF, 2 pages, 147 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9938432&FileExtension=pdf&FileName=Wreckage%20Release%20DMS_Redacted-Rel.pdf
- Photos (item 5, PDF, 3 pages, 379 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9937011&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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