Casualties unknown

Fuel Exhaustion Following Misinterpretation of Sight Gauges Leads to Forced Landing and Nose-Over (N40520)

Prineville, OR, US

On April 27, 2007, a Piper PA-18 (registration N40520) was involved in an aviation accident near Prineville, OR. Investigators recorded the probable cause as: The pilot misinterpreted the fuel quantity sight gauges and failed to visually verify fuel levels during preflight inspection. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards
Aircraft registered N40520
Aircraft registered N40520. Photo: Tequask / CC BY-SA 4.0, via Wikimedia Commons

During preflight, a pilot misread fuel sight gauges, believing empty tubes indicated full tanks. Fuel exhaustion occurred minutes after departure, resulting in a forced landing with nose-over due to excessive braking.

Accident Narrative

On the day of the accident, the pilot conducted a preflight inspection of the aircraft. During the check of the fuel system, the pilot examined the fuel level sight gauges, which consist of clear tubes. He observed that no meniscus point was visible in the tubes. The pilot interpreted this condition as indicating that the fuel tanks were completely full, with the entire sight gauge filled with fuel. Consequently, he did not perform any additional checks to verify the fuel quantity.

Approximately five minutes after takeoff, the engine lost power due to fuel exhaustion. The pilot executed a forced landing on soft, brushy terrain. During the landing roll, the pilot applied excessive braking in an attempt to stop the aircraft before reaching a line of trees. This action caused the aircraft to nose over.

After the accident, the pilot reviewed his fueling log and realized that the fuel tanks had been nearly empty prior to the flight. He then understood that the absence of a meniscus point in the sight gauges was because the tubes were completely filled with air, not fuel. The pilot acknowledged that he had not visually checked the fuel tanks themselves during the preflight inspection, relying solely on the sight gauges.

Probable cause

The pilot misinterpreted the fuel quantity sight gauges and failed to visually verify fuel levels during preflight inspection.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20070514X00564. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.