What happened
On 2 November 2017, an Airbus A320-214, registration EI-GAL, diverted to Cork Airport after the flight crew detected persistent fumes in the cockpit. The aircraft was performing a scheduled commercial flight to London Heathrow when the crew, noticing the smell at flight level 260, donned oxygen masks and declared a MAYDAY. To manage the situation, the crew followed emergency checklists, which included transitioning the aircraft into an emergency electrical configuration using the Ram Air Turbine (RAT). This procedure necessitated manual flying by the commander and resulted in the loss of flight directors.
Upon landing safely at Cork, the aircraft was met by emergency services. Once parked at the stand, the commander initiated a "Rapid Disembarkation" to remove passengers quickly. While most passengers exited via the standard doors, several passengers seated in the emergency exit rows opened the overwing hatches. This led to approximately 3 and 2 passengers disembarking onto the wings, with half of that group utilizing the escape slides. There were no injuries reported during the event, though one passenger required hospital treatment for illness.
The investigation
Investigators examined the aircraft's ventilation system and interviewed the crew and passengers. The investigation focused on the source of the fumes and the sequence of events leading to the unplanned use of the emergency slides. The inspection of the aircraft's avionics bay revealed that the blower fan, which provides cooling to the avionics, was the source of the odor. Additionally, the investigation reviewed the cockpit voice recorder, which noted high workloads for the crew and the specific wording of the disembarkation commands.
Findings
- The primary cause of the fumes was the failure of the rear bearing in the avionics bay blower fan.
- The use of the overwing exits was driven by passenger confusion, exacerbated by the similarity between the "Rapid Disembarkation" instructions and formal emergency evacuation commands.
- Passengers were likely influenced by visual cues, such as seeing emergency responders on the tarmac, and the instruction to use the "nearest available exit."
- The aircraft's electrical configuration during the diversion caused the flight data recorder to lose power, resulting in a gap in the flight data.
- While the overwing exits and slides functioned correctly, the investigation noted that the briefing for exit-row passengers did not specifically cover the distinction between rapid disembarkation and emergency evacuation commands.