What happened
On 21 October 2012, an Airbus A3CO1-131, registration D-AIRX, was conducting a commercial passenger flight approaching London Heathrow Airport. While descending through Flight Level 120, the co-pilot noticed a pungent smell accompanied by irritation in the eyes and throat. The commander confirmed that the cabin crew were experiencing similar symptoms, with the purser reporting the same odour.
As the co-pilot began to feel dizzy and nauseous, both pilots donned oxygen masks and requested priority landing clearance. The aircraft landed without further incident and was halted on a parallel taxiway. Following the shutdown of the engines and air conditioning, the odour began to dissipate, though some passengers continued to report mild throat irritation. The crew members were subsequently transported to a local hospital for medical evaluation.
The investigation
The AAIB examined the aircraft's engines and environmental control systems to identify a potential source of contamination. Inspections of the engines for oil residue or carbon build-up, including borescope examinations of the sump and fan modules, yielded no significant findings. The only notable discovery was some droplets of dirty rainwater within the high pressure compressor of the No 2 engine, which was not considered a cause for the odour.
Testing of the environmental control system configurations during a ferry flight to Frankfurt showed no evidence of engine oil or other abnormalities via electronic analysis. Furthermore, inspections of the galley and toilet areas, as well as the aircraft's lighting and circulation fans, produced no evidence of an odour source. While gas chromatography of the recirculation filter revealed trace amounts of engine oil, these levels were consistent with typical findings.
Findings
- The investigation was inconclusive regarding the specific source of the cabin and flight deck air contamination.
- Laboratory analysis of the recirculation filter found trace amounts of engine oil, but in quantities similar to those found in a different aircraft with no history of such incidents.
- No medical abnormalities were found in the blood tests of the affected crew members.
- The investigation could not establish a definitive link between the observed symptoms and any specific chemical or mechanical failure.