What happened
On the evening of November 1, 1961, a Macchi MB-320 I-ERMI departed Geneva Airport for a series of instrument landing system (ILS) approach exercises. The flight, which included a passenger, was intended as a practice session for upcoming flight reviews. During the second approach exercise, the aircraft experienced a sudden loss of power in the left engine while flying near Nyon. The pilot attempted to mitigate the issue by engaging the cross-feed valve, which temporarily restored power to the left engine using fuel from the right tank.
However, minutes later, while flying near Verso and at an altitude of approximately 2,700 feet, both engines lost power simultaneously. Despite the pilot's attempts to manage the engines, the aircraft entered a glide. Flying through heavy fog and in near-total darkness, the aircraft struck the surface of Lake Geneva about 100 meters from the Vieux Port of Versoix. The impact caused the aircraft to become submerged in the shallow waters of the lake.
The investigation
The investigation focused on the fuel system and the sequence of engine failures. Technical examination of the wreckage revealed that the wing tanks contained only water, and the auxiliary tank was also nearly empty. The investigation established that the fuel gauges, while primitive, were functioning, but the pilot had a habit of relying on time-based fuel estimations rather than direct gauge readings.
Investigators also reviewed the aircraft's recent flight history. Since the last refueling on September 9, the aircraft had performed several short flights and had undergone significant engine idling on the ground in Colombier. By calculating the known consumption rates against the time elapsed since the last known fuel level, investigators determined that the fuel supply was critically low.
Findings
- The primary cause of the accident was total fuel exhaustion.
- The flight was initiated with an insufficient fuel reserve for the intended maneuvers.
- The pilot failed to adequately monitor fuel levels during the flight, particularly during the first approach.
- The loss of power in the left engine was the first sign of depletion, followed by the simultaneous failure of both engines once the right-side fuel was exhausted.
Safety action
- The investigation noted that flight preparations for instrument flying should include a thorough review of weather updates and a robust fuel contingency plan, ensuring that a diversion airfield is always considered if the primary plan cannot be completed safely.