All modern jet aircraft (except the B787) are designed to use bleed air in the cabin. This bleed air comes unfiltered, from the compressor section of the engine, to the cockpit and cabin of an aircraft.

In the early years of aviation, mineral oils were used, but as engine technology advanced and higher internal temperatures were encountered, manufacturers started using synthetic oils. These oils contain a series of additives which can be hazardous to our health if we breath it in, be it as a crewmember or even a passenger. In order to prevent these risks and preserve our health, rules need to be set up at European level. After a long struggle, we finally managed to create an industry-wide working group whose task is to set up a norm within 3 years. BeCA already took part in the first meeting and will continue its active participation. In the mean time, all of us, as pilots, can contribute to this work by reporting any event linked to cabin air contamination.

A bit of history

Adverse effects on health and safety were reported by US Air Force pilots as early as in the 1950s. The problem is thus not new.

Although at the beginning of aviation bleed air was not used, it started being used with the introduction of the Caravelle in 1957. In the 60s, both bleed air systems and turbo compressors or blowers (ex B707, DC-8, etc.) were used to pump in air in the cabin. They did not have an oil fumes issue, but were too heavy and consumed too much fuel, so a bleed air system was gradually used in all airplanes.

What is wrong?

The design has not changed since the beginning of its use, and the main issue is that the air/oil seal supposed to prevent engine oil from “entering” the cabin can, by design, leak. The proper functioning of the oil seals depends on air pressure. During pressure build-up (e.g. engine start) and transient operations (e.g. changes in thrust lever angles), small pressure surges occur and oil mists can enter the cabin air.

Without getting into too much technical detail, many of you are already aware that oil smell, or, more generally, contaminated cabin air (hydraulic, de-icing fluids, etc.), is a hazard to flying. As a result of breathing in contaminated air, we can encounter the following symptoms : blurred vision, headache, nausea, slower reaction time, problems concentrating… and the list goes on.

Some cases even lead to incapacitation of pilots with long-term health effects or even loss of medical certificate.

Although an airplane is equipped with cabin temperature and cabin pressure indication, it does not have a detection system to warn us about contaminated air.

The only way to know if we suffer from contamination is to smell it. The neurotoxic components in the oils itself are odourless, but other components of the oil offer a good indication. However, smelling can be subjective, as some of us are really sensitive to it and others not at all.

Currently, besides troubleshooting the pack it comes from, our only solution is to don the oxygen mask once we are confronted with contamination, and the only weapon we have is to report any event of contamination, through an ASR and in the aircraft techlog. It does not matter whether you felt ill or not.

Underreporting of contamination events is the biggest obstacle to moving forward.

What are the rules and standards?

Until 2013, a European norm on exposure standards (CEN 4618/4666) existed. Unfortunately, this standard was not suitable to the aviation world as it only related to non-heated mixtures, exposures of 8h maximum, only 1 chemical substance at a time without considering their synergetic effects. It did not protect passengers or crewmembers’ health. Moreover, the standard described some typical chemical substances that also apply to indoor quality of buildings, but it did not even look into the chemicals that are used in the engine oils.

Thanks to the efforts of different organisations (passenger/consumer and pilot/cabin crew associations, etc.), including BeCA, this norm was revoked in 2013.

Today, after a lot of content work, we are in a position to set up a new norm (CEN/TC436) thanks to the creation of CEN working group.  The CEN is the European Committee for Standardisation which aims to create a norm through a platform (technical commission) where all stakeholders try to reach a consensus at European Level. This commission is composed of representatives from the whole industry coming from all over Europe: pilots, cabin crews, aircraft/engine manufacturers, national norm offices as well as consumer/travellers’ associations. Belgium is represented through BeCA.

A first meeting took place on April 20th in Brussels at the CEN headquarters, which aimed at setting a timeline and working method. Once a consensus is reached, the norm will have to be applied by all European countries. As you can imagine, every party has its own point of view and finding a consensus will be no easy task.

Not only do we need to be able to identify the problem, but we must also set the lowest possible thresholds, get an approved sampling/measurement that can lead to detection instruments with cockpit warnings and training, but most importantly, we also need to have proper preventive health and safety standards on aircraft.

The whole process should take around 3 years (if there is no extension), and there will be 3 to 4 meetings per year, the next one being planned in early July.

Change does not happen over night, nor can it happen through an individual effort. Therefore, BeCA is working in close cooperation with sister associations to help shape the cabin air quality of tomorrow and you can help by reporting any contamination event you might encounter.

If you have any questions or want further information, don’t hesitate to check our website or to contact us.

ECA Task Group on Cabin Air Quality
Congratulations to Vinciane Cabaret for her position as chairwoman!

At the November 2014 ECA Conference, it was decided to create a Task Group on Cabin Air Quality. The aim of the group is to develop a common position at European level and share information and practices. The group met for the first time on 10 June and plans to meet two-three times a year. At the first meeting, the Terms of Reference were approved and the chair was appointed: we are proud to have our Assistant Secretary and expert in cabin air quality, Vinciane Cabaret, as chairwoman of the group.