Background
On 22 June 1984, a privately operated Piper PA-23-160, registration I-GTOR, departed Milano-Bresso, Italy, at 1533 UTC for a short flight to Milano-Linate to clear customs. After completing formalities, the pilot, accompanied by three passengers, departed from Milano-Linate at 1629 UTC for a VFR/IFR flight (Z-flight plan) to Paris-Le Bourget.
Flight History
Shortly after departure, at 1632 UTC, Linate Tower instructed the pilot to contact Milano-Information, which he did at 1637 UTC. At 1644 UTC, the pilot contacted Milano-Malpensa Tower. Radio transmissions were described as unclear and difficult to understand. A film recovered from a damaged camera taken by one of the passengers provided insight into the flight path. The last six images indicate the aircraft flew south of Domodossola, then southwest of Simplon, and subsequently over the Upper Valais region between Mörel and Fiesch, heading westward at an altitude near 12,000 ft MSL. The aircraft appeared to be flying near the top of scattered clouds, with the peaks of the Bernese Alps mostly cloud-covered. At 1718 UTC, the pilot made contact with Geneva-Information on frequency 126.35 MHz and communicated with them until the accident.
Accident
At approximately 1746 UTC, the aircraft, flying under instrument meteorological conditions (IMC), collided head-on with the north wall of Grossstrubel, a mountain in the canton of Bern, Switzerland. The four occupants sustained fatal injuries, and the aircraft was destroyed. No third-party damage occurred. The wreckage was not discovered until 29 June 1984, when a hiker found it.
Weather
According to the Swiss Meteorological Institute, the general weather situation featured a small intermediate high with some cloud buildup on the northern side of the Alps. At the accident site, the cloud cover varied: on the Valais side, 2-8 oktas with base at 2400-2700 m; on the Bernese side, 5-7 oktas with base at 2000-2300 m. The cloud top was estimated at FL 130. Visibility was more than 30 km outside clouds. Wind was from the west-northwest at about 15 kt. Temperature was 2°C, dew point 0°C, QNH 1017 hPa. Hazards included slopes and peaks partially cloud-covered. The flight weather forecast valid from 12 to 18 UTC for the Alps indicated 6-8 oktas on the northern side with bases 1200-1700 m, isolated rain showers, and improving visibility.
Cause
The accident was attributed to:
- Continuation of a visual flight rules (VFR) flight into instrument meteorological conditions (IMC),
- After a total loss of orientation over the high mountains.
Contributing Factors
The following elements may have played a role:
- Insufficient flight preparation,
- Impairment of radio navigation aids due to topography.
Investigation
The investigation was led by Ernst Guggisberg and concluded with the submission of the report on 22 June 1987.