Investigation Summary
The aircraft was a specialized variant of the Curtiss Condor II, one of only a few operated by Swissair, and had been in service for only four months (MSN 53, manufactured in 1934). During a scheduled flight from Zurich to Berlin with planned stops in Stuttgart and Leipzig, the crew encountered severe weather shortly after crossing the German border. The investigation focused on the separation of the wing structure. While most reports, including the German commission, identified the failure as originating in the starboard (right) wing and engine mount due to defective welding and oscillations, some records (ASN) suggest the port inter-wing strut failed first, leading to the separation of the engine and part of the lower wing. The extreme turbulence encountered within the thunderstorm provided the final force necessary to cause the weakened structure to fail completely, resulting in an uncontrolled descent from 3,000 meters.
Final Conclusions
The investigation concluded that the primary cause was a structural failure of the right wing. This failure was triggered by pre-existing stress fractures in the wing and engine-mount assembly. These fractures were caused by poor welding quality and construction defects, exacerbated by engine-induced vibrations. The severe turbulence of the thunderstorm acted as the final catalyst, causing the compromised wing to separate from the aircraft.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Wing and Engine Mount Structure
The investigation found that defective welding and construction techniques led to fatigue fractures in the assembly connecting the engine to the wing.
Airframe
The Curtiss AT-32C featured a biplane configuration; the failure involved the separation of the starboard wing assembly under aerodynamic stress.
Interesting Facts
- 01The accident resulted in the death of Nelly Diener, Europe's first official air stewardess.
- 02The aircraft, MSN 53, was manufactured in 1934 and had been in service for only four months.
- 03It was the deadliest aviation accident of 1934.
- 04The Curtiss AT-32C was a specific variant developed for Swissair, which was its sole operator.
- 05The wreckage was found approximately 30 km north of the Swiss-German border near Tuttlingen.
Safety Actions & Advisories
Fleet Grounding and Inspection
Source ↗Following the accident, Swissair grounded its remaining Curtiss Condor aircraft to inspect for similar fatigue fractures in the wing and engine mount structures. The investigation's findings regarding defective welding led to increased scrutiny of construction techniques for high-stress biplane components.