National Transportation Safety Board
Aviation Accident Preliminary Report
Date & Time:
05/28/2020, 1600 AKD
Flight Conducted Under:
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 airline transport 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. The purpose of the flight was to move personnel around the state in support of wildland firefighting operations.
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 last thing the pilot remembered of the accident flight was guiding the airplane to the off-airport landing site.
According to the fuel vendors fuel truck driver, 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.
The airplane was equipped with two, Lycoming IO-540 series engines.
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 and Owner/Operator Information
State Of Alaska
Operating Certificate(s) Held:
Meteorological Information and Flight Plan
Conditions at Accident Site:
Condition of Light:
Observation Facility, Elevation:
Distance from Accident Site:
15°C / 2°C
Lowest Cloud Condition:
Few / 6500 ft agl
Wind Speed/Gusts, Direction:
Light and Variable / , Variable
Overcast / 12000 ft agl
30.16 inches Hg
Type of Flight Plan Filed:
Wreckage and Impact Information
61.581667, -159.543056 (est)
Investigator In Charge (IIC):
David B Banning
Additional Participating Persons:
Anthony Mattingly; Federal Aviation Administration; Anchorage, AK
The NTSB did not travel to the scene of this accident.