Cessna 172S HB-CQW Emergency Landing at Kappel am Albis

Incident Overview and Aircraft Details On 27 November 2011, a Cessna 172S registered as HB-CQW, operated by Sportfluggruppe Swissair, made an emergency landing in a meadow at the eastern end of Kappel am Albis, Canton of Zurich, at 14:43 local time. The aircraft was being flown by a Swiss private pilot for a solo training flight under visual flight rules (VFR). The pilot was not injured, and the aircraft sustained no damage, though minor field damage was reported. ## Flight History and Fuel Planning The pilot departed from Hausen am Albis (LSZN) at 13:10 for a planned 90-minute training flight to the Clariden, Limmern, and Glärnisch region, with a planned altitude of 11,000 ft QNH. The pre-flight fuel calculation, based on an aircraft weight of 2,550 lb, estimated a total fuel requirement of 20.1 US gallons for 2 hours and 21 minutes of flight, including a 45-minute reserve. During the pre-flight inspection, conducted inside the hangar with half-open doors, the pilot measured 50 liters in the right wing tank and 40 liters in the left wing tank using a stick gauge, totaling 23.8 US gallons. ## Fuel Indication Discrepancy and Engine Failure At takeoff, both cockpit fuel gauges indicated approximately 10 US gallons per side. The fuel selector valve was set to 'both'. Approximately 25 minutes later, the aircraft reached 11,000 ft QNH and the pilot began the planned training maneuvers. At 14:30, during the descent check, the pilot noticed both fuel gauges reading slightly below 5 US gallons per side, whereas he expected 10 US gallons total (5 per tank). He recalculated his fuel state, estimating he still had over 10 US gallons remaining, and proceeded with the flight. As the aircraft descended toward Hausen am Albis, the engine began to run roughly at approximately 2,900 ft QNH. The fuel gauges then read 3 US gallons in the left tank and 2 US gallons in the right tank. The pilot attempted to restore engine power by adjusting the mixture and throttle, checking the fuel shut-off and selector valves, and activating the electric fuel pump. These measures were unsuccessful, and the engine lost all power. The pilot decided to make an emergency landing at a meadow at Kappel am Albis at approximately 2,400 ft QNH. ## Post-Incident Actions and Investigation After the landing, the pilot contacted the police, who informed the Swiss Accident Investigation Board (SUST). The pilot also contacted the technical manager of Sportfluggruppe Swissair and arranged for fuel. The pilot stated to police that a technical problem had caused the emergency landing. The following day was expected to be foggy, so the pilot intended to fly the aircraft back to Hausen am Albis the same day. The technical manager inspected the aircraft and refueled the left wing tank with 40 liters. After a ground run and a field inspection, the pilot took off at 16:48 and landed uneventfully at Hausen am Albis. This flight was conducted without SUST authorization or a permit from the Federal Office of Civil Aviation (BAZL), contrary to SUST instructions. ## Probable Cause The SUST determined that the serious incident was caused by an emergency landing due to engine failure from fuel exhaustion. Contributing factors included: - The fuel level was not correctly determined before the flight. - The left and right fuel level sensors were installed in reverse, resulting in incorrect low-level indications for the wing tanks. - The flight was continued as planned despite a detected discrepancy between the fuel gauge readings and the expected fuel quantity. - The low fuel reserve warning on the alarm panel was ignored.