What happened
Following the disembarkation of passengers from an Embraer 170 at Zurich Airport (LSZH), the cabin crew chief notified the pilot that the evacuation airstair was partially extended and supported by stairs. Upon notification, the flight crew consulted with the Maintenance Control Center (MCC) and requested mechanical assistance to rectify the issue.
During the process, it was noted that the pilot had not received a standard report from the cabin crew chief regarding the completion of passenger disembarkation, nor was the pilot made aware that the airstair had been deployed during the period the aircraft was at the gate.
The investigation
The investigation focused on the operational status of the airstair and the communication between the cabin and cockpit crews. Investigators reviewed the airworthiness certificates and the maintenance history of the equipment, confirming that the airstair was fully functional and in good working order during its operation.
Technical analysis revealed that the airstair did not fully deploy because the clearance between the floor of the jet bridge and the lower edge of the aircraft door was insufficient to trigger the mechanism. This specific design feature serves as a built-in safety measure to prevent the accidental deployment of the stairs.
Findings
- The primary cause of the incident was the failure of the cabin crew to notice that the evacuation airstair had been extended from its storage compartment.
- The crew's adherence to established training procedures prevented the situation from escalating into a more serious safety event.