Incident Overview
On October 26, 2017, at 12:02 local time, a privately operated Robin 155CDI aircraft (registration HB-KLM) experienced a loss of engine power while cruising near Schwarzsee, Switzerland. The pilot, a Swiss national born in 1963 holding a PPL(A) license with 518 total flight hours (119 on type), intended to conduct a local sightseeing flight departing from and returning to Zweisimmen Airport (LSTZ).
Flight Sequence
The pilot noted that the fuel indicator displayed a tank level of 75%, but he was aware that the gauge did not always provide accurate readings. The planned route passed over the Tsanfleuron area toward Spiez via the Fribourg (FRI) beacon. While flying at approximately 7500 ft AMSL in the Schwarzsee region, the engine began to stutter.
Assessing the situation, the pilot decided to return to Zweisimmen, with a backup plan to land in a large field near Boltigen if necessary. The aircraft landed without incident on Runway 17 and, upon taxiing to a stop at the end of the runway, the engine shut down. After refueling, the pilot discovered that no fuel reserve remained in the tank.
Findings
No injuries were reported to the pilot, passengers, or third parties. The aircraft was not damaged, and no third-party damage occurred. The flight was conducted under visual flight rules (VFR) in private operation.
The Swiss Transportation Safety Investigation Board (STSB) concluded that the power loss resulted because the pilot did not pay sufficient attention to the fuel supply, despite knowing that the fuel indicator was malfunctioning. No further investigation was conducted, and the case was closed with a summary report.