An aircraft is beginning its final approach when the pilots notice an unusual odour in the cockpit. Without warning, the First Officer becomes nauseous and his arms and legs start to feel numb. The Captain starts to experience similar symptoms, although he is less severely affected. Both put on their oxygen masks, but the First Officer is now unable to comprehend or follow what is happening. The Captain decides to land without completing the pre-landing duties as he does not feel able to perform a go-around.

Although this may sound like a scene from a disaster movie, these events happened on a flight from Vienna to Cologne on 19 December 2010. The aircraft was able to land safely, although both pilots were deemed unfit to work for six months. But what was the cause and why did it occur?

Since the inception of high-altitude commercial aircraft, it has been necessary to find ways to provide a continuous supply of pressurised air for the cabin. In earlier jet engines, separate mechanical compressors were used to achieve this. However, it was soon recognised that jet engines heat and compress air as part of the propulsion process, whilst the air is in the forward section of the engine. This pre-heated and compressed air can be “bled off” from the engine and pumped straight into the cabin after being cooled. Since the 1960s, bleed air jets have been used for all commercial airliners with the exception of the Boeing 787 Dreamliner.

Although generally considered safe, bleeding off air from the engines is not risk-free. Bleed air can occasionally become contaminated by pyrolised compounds such as engine oil, de-icing or hydraulic fluid. The contamination can occur through mechanical failures, the overfilling of oil or hydraulic fluid reservoirs, ingestion of de-icing fluid through the auxiliary power unit and even the engine design itself. This is what is commonly referred to as a “fume event”. Although there is currently no agreed definition as to what constitutes a fume event, it may involve hazy smoke in the cabin and is normally categorised by the presence of a strong smell.

Whilst contamination can occur from various substances, the media most often focus on contamination by jet oil. The reason behind this is that, while contamination of bleed air by hydraulic or de-icing fluid can cause short-term irritation to the eyes, nose and throat, these substances are not generally linked to long-term health effects. However, in the case of jet oil, organophosphates are used as “extreme-pressure additives”, which provide lubrication and anti-wear properties to the jet engine in very high temperatures and pressures. Of particular concern is the organophosphate tri-ortho-cresyl phosphate (or TOCP), which is known to be toxic to the nervous system in very high quantities.

The legal regime in relation to fume events

The Montreal Convention 1999 (or the Warsaw Convention 1929, depending on the passenger’s itinerary) would govern claims by passengers against air carriers. The Convention would not apply to claims against manufacturers or other defendants, although carriers may choose to seek indemnity from them.

In Air France v Saks, the US Supreme Court defined an accident under Article 17 of the Warsaw Convention as “an unexpected or unusual event or happening that is external to the passenger” and not “the passenger’s own internal reaction to the usual, normal and expected operation of the aircraft”.

If a court were to find that a fume event was sufficiently serious to constitute an “accident” – in other words that the fume event was “unexpected or unusual” from the passenger’s perspective - then, assuming a passenger could show “bodily injury”, the airline’s liability would be likely to engage.

Cases involving cabin crew

A legal precedent has been set establishing a connection between fume events and long-term health effects in the Australian case, Turner v Eastwest Airlines. Joanne Turner claimed against her former employer, Eastwest Airlines, for injuries she allegedly sustained after being exposed to “thick smoke” during a twenty minute fume event on a BAe146 flight to Brisbane on 4 March 1992. Ms Turner, who was five months pregnant at the time of the incident, said that she had immediately started coughing and experienced a burning throat, sore eyes and headache. When her persistent cough failed to improve and became chronic, she brought a claim before the Dust Diseases Tribunal in New South Wales, relying on the applicable workers’ compensation statute, claiming that her former employer had negligently exposed her to fumes, chemicals and dust, which had caused the persistent cough. She sought both economic and non-economic damages in compensation.

The Tribunal found that Ms Turner had been exposed to oil fumes and smoke and determined the cause as an engine oil leak in the auxiliary power unit. The failure of the auxiliary power unit’s oil seal was found to be foreseeable, as was the risk that smoke from leaking oil would enter the cabin. The Tribunal agreed with Ms Turner that the airline did not take reasonable steps to mitigate the risk of an oil leak contaminating the cabin air, despite knowing that the faulty compressor seals could emit vaporised oil into the bleed air system. The auxiliary power unit in question had recently been leaking oil and cabin smells had been reported. However, steps had not been taken to locate and remedy the source of the smells.

The Tribunal held that toxic particles of vaporised engine oil had caused Ms Turner’s long-term adverse health problems and she was awarded approximately USD 129,000. The Tribunal further found that Ms Turner’s symptoms put her at a disadvantage in the labour market and caused her to suffer a loss of earning capacity. Ms Turner was therefore awarded damages for non-economic loss, past and future loss of earnings, medical expenses and out-of-pocket expenses.

Eastwest Airlines appealed to the New South Wales Court of Appeal and then to the High Court of Australia, but lost both appeals (the latter being heard on 3 September 2010). Although this decision is not binding in courts outside Australia, it could have persuasive effect.

In another case involving a member of cabin crew, former American Airlines flight attendant Terry Williams is believed to have been the first person in the US to settle a fume events claim against Boeing. She claimed the manufacturer knew that the MD-82 aircraft and its bleed air system were defective, but did nothing to protect her or the passengers and other crew members from toxic fumes that entered the cabin, as American Airlines flight 843 taxied to the gate at Dallas airport on 11 April 2007. The fume event allegedly caused her to suffer tremors, memory loss and severe headaches amongst other ailments. Details of the settlement are confidential.

Whilst these cases may appear to set a precedent for future claims, it is important to highlight that they are distinguishable from passenger claims, as they are not governed by the Montreal or Warsaw Conventions, as passenger claims are.

Recent and future claims

Both flight attendants and passengers have filed toxic cabin air claims in the US courts in recent years. Defendants  have included airlines and aircraft manufacturers, as well as aircraft engine manufacturers, manufacturers of air- conditioning and pressurisation systems, aircraft owners and lessors. The courts have yet to consider the merits of these cases, because the claims have either been dismissed or withdrawn.

Such a claim has recently been filed against Delta Airlines and Airbus before the Circuit Court of Arlington County. Christopher Kamyszek, who was a passenger on board a Delta Airlines flight from Salt Lake City to Minneapolis on 16 December 2011, is seeking USD 5 million compensation for alleged loss of enjoyment of life, ability to earn a living and employment, as well as damages for mental pain and suffering and permanent, debilitating physical injury. He claims he was injured by a fume event on board the aircraft, approximately fifteen minutes after take-off. It remains to be seen whether this case proceeds to trial.

It is also possible that passengers in particular may be able to claim that a carrier failed to warn them of the possible presence of cabin air contaminants. In a class action lawsuit against United Airlines in 2004 (In re UAL Corp), the named claimants, Richard and Sharon Dorazio, flew from Los Angeles to Sydney on a United Airlines flight where insecticides were sprayed in the cabin before and during the flight, as legally required for all aircraft entering Australia and New Zealand. It was claimed that Mrs Dorazio became ill as a result of exposure to the insecticides, and that the spraying of insecticide constituted an Article 17 Montreal Convention accident, because it was unexpected and, had they been warned in advance of the disinfection, no such accident would have occurred, because they would have taken the appropriate action. The court rejected the claimants’ arguments, citing the deep vein thrombosis decisions that have “uniformly declined to find Article 17 accidents in the absence of an airline’s deviation from ordinary operating standards”. It is to be hoped that other courts would follow this reasoning and hold that airlines have no duty to warn passengers about the possibility of fume events or contaminants that may be present during normal aircraft operation.


In light of the growing media coverage and cases of the kind discussed above, it seems likely that further pressure will be applied to the airline industry to address concerns surrounding bleed air and the risks of contamination during fume events.

The Boeing 787 Dreamliner is the only modern commercial aircraft that uses an electric compression system and therefore does not use bleed air from the engines. It is yet to be seen whether or not other aircraft models will follow suit.

What is clear is that there is a growing call to retro-fit contamination detection systems and bleed air filtration to aircraft. Many would like to see organophosphates removed from jet oil altogether, and such oils are already in development. However, given the proven effectiveness of organophosphates as anti-wear agents, it is not clear how widely these new organophosphate free oils will be taken up throughout the aviation industry.

Whatever the final solution, there is likely to be an impact on airlines in the coming years. Should a passenger succeed in proving a causal link between a fume event and health issues, airlines will have to take steps quickly to avoid potentially significant litigation costs.