What happened
On March 27, 1961, a Noorduyn UC-64-A, registration HB-UIL, was conducting a flight from Lomé to Libreville. During the transit, the aircraft encountered heavy rainfall and darkness. As the fuel supply reached a critical level, the pilot was forced to perform a crash landing in difficult terrain near Rio Benito, Spanish Guinea (now part of Equatorial Guinea). The impact resulted in the destruction of the aircraft. While the pilot escaped without injury, the second crew member sustained serious injuries.
The investigation
The investigation was conducted via a summary procedure by the Swiss Federal Aircraft Accident Investigation Commission. The commission reviewed a report from the Bureau of Aircraft Accident Investigation dated July 4, 1961, as well as a pilot's report from May 12, 1961. The commission also noted that an inquiry sent to the Spanish aviation authorities in Madrid on April 7, 1961, received no response. Additionally, the investigation established that at the time of the accident, the aircraft was no longer operated from Switzerland, and the owner, a German national, did not appear to be a resident of Switzerland.
Findings
- The primary cause of the accident was inadequate flight planning, specifically the failure to calculate an adequate time reserve to allow for the safe reaching of an alternate airfield in the event of weather-related delays.
- The aircraft was operating with insufficient fuel reserves to manage the impact of heavy rain and nighttime conditions.