What happened
On July 4, 2018, at 08:41 UTC, an Airbus A330-343, registration HB-JHH, was conducting a scheduled commercial flight from Zurich Airport (LSZH) to Johannesburg (FAOR). While operating under instrument flight rules, approximately 100 km west of the southern tip of Corsica, the flight crew detected a strong odor within the cockpit area.
As the smell persisted, the crew noted that their operational performance was partially impaired. Due to the nature of the situation, the decision was made to terminate the flight and return to the departure airfield. The aircraft successfully completed an unscheduled landing back at Zurich Airport.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) initiated an investigation into the incident to determine the source of the odor and the extent of its impact on the crew's ability to operate the aircraft safely. The investigation focused on the circumstances surrounding the detection of the smell and the subsequent flight management decisions.