What happened
On January 26, 2006, an AVRO 146-RJ100, registration HB-IXR, operated by Swiss European Air Lines, arrived at Zurich Airport from Hannover. After taxiing to stand A-57, the crew began performing the parking checklist. During this process, a blue and yellow flame accompanied by heavy black smoke appeared near the co-pilot's rudder pedals.
Due to the unidentified source of the fire, the captain ordered an immediate emergency evacuation. Because a passenger boarding bridge was already connected to the aircraft, the emergency slide failed to deploy properly upon opening the forward left door, landing on the bridge floor. Consequently, the crew transitioned to a rapid disembarkation, successfully evacuating all passengers and cabin crew within two minutes.
After the aircraft had come to a complete stop, a ground service worker attempted to connect the external power supply. Upon switching on the power at the dock, intense smoke was observed at the connection point, prompting an immediate alert to the airport fire department.
The investigation
SUST examined the aircraft, the ground power equipment, and the operational procedures used during the winter de-icing process. The investigation focused on the technical state of the dock-side connector and the chemical composition of the residues found on the electrical components. Investigators also reviewed the crew's adherence to emergency checklists and the ground worker's compliance with power connection protocols.
Findings
- The primary cause of the incident was a short circuit triggered by the presence of de-icing fluid within the dock-side electrical connector.
- Chemical analysis confirmed that the connector had been contaminated by aircraft de-icing fluid, which is known to pose risks of corrosion and electrical failure.
- During the evacuation, the co-pilot failed to follow the full emergency checklist, specifically neglecting to shut down the Auxiliary Power Unit (APU), which contributed to uncertainty during the evacuation process.
- The ground worker followed all established safety procedures, and the investigation noted that the recent modification requiring power to be switched on from the dock (rather than at the plug) prevented potential serious injury to the worker.
Safety action
Following the incident, the airport authority implemented several safety measures, including:
- The installation of protective sleeves for all dock-side connectors to shield them from environmental contaminants.
- A new requirement to perform insulation measurements on 400 Hz power connections within 24 hours of any surface de-icing operations.
- Updated safety instructions for ground personnel, strictly prohibiting contact between power cables and de-icing fluids and mandating that the person plugging in the cable must also be the one to switch on the power.