On 27 May 2008 an Airbus A319-100 being operated by Germanwings on a scheduled passenger flight from Dublin to Cologne was 30nm east of Dublin and passing FL100 in the climb in unrecorded daylight flight conditions when the Purser advised the flight crew by intercom that “something was wrong”, that almost all the passengers had fallen asleep, and that at least one of the cabin crew seated nearby was “unresponsive”. Following a review of this information and a check of the ECAM pressurisation page which showed no warnings or failures, a decision was taken to don oxygen masks and the aircraft returned uneventfully to Dublin without any further adverse effects on the 125 occupants. A MAYDAY was declared during the diversion.
An Investigation was carried out by the Irish AAIU with assistance from the German Accident Investigation Board (Bundesstelle für Flugunfalluntersuchung (Germany) (BFU)). It was noted that the aircraft had only recently been delivered new from the manufacturer and had only been in service for six weeks prior to the investigated event. It was also noted that the flight had been the fourth sector of a morning duty for the complete crew in the same aircraft.
Following the flight, none of the passengers requested medical intervention or expressed concern in that respect and comprehensive tests on the crew, who all reported having felt slightly unwell or experienced other abnormal symptoms including drowsiness and slight dizziness during the flight, were negative. The symptoms reported by the crew had disappeared quickly after they went onto oxygen. Consequently, none of them requested medical attention when this was offered.
A thorough examination of the aircraft found no evidence of oil loss from the engines or APU and the possibility of the passage of oil into the air conditioning system was discounted. As the aircraft had not been de-iced prior to flight, it was considered that residual de-icing fluid could not have been present in the cabin air intake ducts. Passenger carry-on baggage, having been subjected to the normal security screening process, was not further examined. However, the hold baggage was examined but no evidence of any hazardous or suspicious substance was found. The sensor test conducted by the AFRS prior to the passengers disembarking, found nothing abnormal and a detailed search of the aircraft interior, including the under-floor area, found nothing of significance.
After three days of investigations at Dublin, the aircraft was ferried to the manufacturer’s base for further inspections but there were no further findings, and it was decided to release the aircraft to service following which there was no repetition.
Overall, the Investigation was “unable to find any evidence of contamination of the aircraft air supply, which might have caused fatigue, sleepiness, dizziness or any other symptoms of feeling unwell among the flight crew. Neither can the Investigation explain why only some of the passengers complained of any symptoms and that the symptoms of the (affected) passengers were limited to drowsiness, i.e. no passengers reported feeling unwell. The fact that those who reported the symptoms recovered rapidly after landing would indicate the absence of any toxic contaminant. The failure to detect any abnormal residues within the aircraft after the event would also suggest the absence of toxic contaminants.”
The Investigation also found no evidence of a restricted, poor quality or inadequate air supply to the flight deck or to the cabin, no evidence of any loss of pressurisation and no evidence of any contribution to the event attributable to crew fatigue.
In respect of the response to the event, it was noted that current regulatory standards in Ireland do not specify the provision of a medical centre at major international airports and thus do not satisfy ICAO SARPs. The Investigation also expressed concern that the occupants had not been allowed to disembark from the aircraft more promptly after arrival back in Dublin, given the potentially adverse consequences had the aircraft or cabin air been significantly contaminated.
It was concluded that the probable cause of the adverse symptoms reported by the aircraft crew and some passengers could not be determined.
Three Safety Recommendations were made as a result of the Investigation as follows:
- The Irish Aviation Authority (IAA) should review the licensing requirement of major airports in Ireland, as specified in the Manual of Aerodrome Licensing, to comply with ICAO guidelines for large airports and to ensure that the provision of adequate medical services are part of the licensing provisions. (IRLD2010012)
- Dublin Airport Authority (DAA) should review the provision of medical services at Dublin Airport. (IRLD2010013)
- Dublin Airport Authority (DAA) should review the response procedures to ensure that passengers and crew are not unduly detained in a potentially toxic environment, following cabin air quality events. (IRLD2010014)
The Final Report of the investigation was published on 15 July 2010 and may be seen in full at SKYbrary bookshelf:AAIU Report No: 2010-008