Flight History
The aircraft, a Piper PA-28 RT-201 registered as HB-PDU, departed Grenchen Airport at 1330 local time for a commercial VFR scenic flight over the Alps with four persons on board. The outbound route passed over Lake Biel, Fribourg, Plaine Morte, and the Matterhorn; the return leg went via Saas-Fee, Bettmeralp, Jungfraujoch, Langnau, and Burgdorf. While over Langnau, the pilot listened to the Grenchen ATIS and received clearance to enter the airport traffic zone via waypoint "SIERRA." During descent toward the entry point, the pilot performed approach checks. When he moved the landing gear lever to the down position, he noticed that the digital displays of the radio and navigation instruments had gone blank. Assuming an electrical failure, he executed the procedure reserved for aircraft without radio, flew a volte, and approached runway 07 with the landing gear still retracted.
Events Leading to Landing
The Grenchen air traffic controller called the pilot multiple times without response, then fired a red flare. At approximately 1515 local time, the aircraft touched down on its belly and came to a stop near the VOR. The four occupants were uninjured and evacuated the aircraft without assistance.
Technical Findings
Post-accident examination of the landing gear mechanism and electrical system revealed no defects. The master switch was found to have been inadvertently turned off, likely when the pilot intended to activate the electric fuel pump. The switch's placement next to the fuel pump switch on the right side of the instrument panel was noted as conducive to error. The aircraft was equipped with Piper Service Bulletin No. 866, which disabled the automatic gear extension feature, a fact known to the pilot.
Weather Conditions
At the time of the accident, weather was mostly clear with 3/8 cirrus clouds, visibility approximately 10 km, wind from the northeast at 10 knots, temperature 2°C, dew point -5°C, and QNH 1005 hPa.
Cause
According to the investigation, the accident was due to a belly landing resulting from failure to extend the landing gear, which in turn was caused by a manipulation error during approach checks. Contributing factors included non-application of the emergency checklist, the pilot's low experience on the aircraft type, lack of familiarity with the landing gear system, and the inadequate positioning of the master switch.