Passengers climbed out through emergency exits onto the wings of an Aer Lingus aeroplane when they panicked after the pilot told them to disembark rapidly at Cork Airport.
Cabin crew later told investigators the passengers may have panicked when they saw fire crew with hoses surrounding the airbus 320 after it parked after the November 2017 incident.
Tensions were also likely heightened because the announcements telling them to disembark rapidly sounded louder due to the pilots wearing oxygen masks, a report from the Air Accident Investigation Unit heard.
The upshot was that passengers seated in the emergency exit rows opened the overwing emergency exits and approximately 32 passengers climbed out onto the aircraft wings.
Half used the escape slides and the other half returned to the passenger cabin and exited the aircraft using the front and rear steps. There were 143 passengers in total, and six crew.
Cabin crew later noted that passengers “wouldn’t necessarily know the difference between a ‘disembark’ and an ‘evacuate’ instruction”.
The incident that led to the rush to disembark began when the Aer Lingus flight travelling from Cork to London Heathrow was forced to return to Cork when the flight crew smelled fumes about 20 minutes after takeoff. It was the second time that day that they had noticed a burning smell.
The flight crew donned oxygen masks and declared a Mayday and decided to return to Cork. After they had parked, the pilot addressed passengers advising them to “disembark the aircraft immediately”. Passengers were told to leave cabin baggage behind.
One passenger told air accident investigators that the pilot was “excellent” but that the disembarkation was “chaotic”.
He said the emergency lights were not on, that the aircraft became “stuffy” and that his wife identified an unusual smell. He said he became trapped, unable to move to the front or rear of the aircraft. He said a passenger with restricted mobility was being assisted by cabin crew but this prevented other passengers from exiting. As a result, some passengers opened the overwing exits and climbed onto the wing.
He described the “evacuation” as frightening and that people were upset. He became unwell shortly after getting off the aeroplane and was taken to a local hospital.
Investigators said a “misinterpretation” of the pilot’s instruction was understandable “when one considers the entire sequence of events”.
A subsequent inspection by maintenance workers found the source of the fumes in the cockpit was due to bearing wear in an avionics bay blower fan (the fan pulls in cool air and prevents electronics from overheating). The fan manufacturer was already aware of issues relating to bearing wear and had recommended scheduled overhauls of the fan unit. Since the incident, the fan manufacturer has made further efforts to improve fan reliability. A new fan design is expected this year.
Aer Lingus has also reviewed its rapid disembarkation procedure and intends to revise it so that there is clearer understanding of the difference between a rapid disembarkation and a full emergency evacuation.