Cabin Air Contamination – A Safety Issue

There has been much media attention about cabin air events recently. The German Parliament had a hearing about the issue and decided it was up to Europe to take action; whilst the European Aviation Safety Agency just published its Decision that they are not going to act. Although experts disagree on possible long-term health effects from cabin air contamination, one thing is clear: when a fume event occurs, cabin air contamination can cause short-term health effects which compromise flight safety. Whilst research and new technologies may offer solutions in the future, we should act today by reinforcing training and procedures.

Due to the design of engines in combination with bleed air systems, oil fumes may enter the air-conditioning packs and pollute cabin air. As air flowing through the bleeds is not filtered, cabin air can be contaminated by chemicals from the engine oil.

When such a fume event occurs, the crew has to follow the relevant operating procedures and checklists which stipulate the donning of the oxygen mask, assure 100% oxygen supply to operating crew and then terminate the flight as soon as possible. In order for the crew to react correctly, ECA strongly believes that pilot training on the immediate actions is to be reinforced:

  • Checklist terminology ‘smoke / fire / fume’ should be clarified, as to non-native English speakers, it may not be obvious that fumes can be invisible. Furthermore, crews should be trained to react on an unexplained odour.
  • Some checklists state the donning of oxygen masks is only necessary “if required” whilst others make it a priority and compulsory. There should be only one standard practice and ECA recommends to always don the oxygen mask during a smoke / fire / fume event. Training in the correct use of oxygen masks should also be reinforced.
  • If after a fume event the crew feels unwell, they should consult a medical doctor.

ECA is aware of the continuous development of filtering systems (both from the bleed and in re-circulated air), of detectors (real time, airborne) and research on engine oil composition. Also some new airplane designs have different architecture not making use of bleed air from the engines for the air-conditioning. It will be important to evaluate the frequency of fume events in these new airplane designs and the advantages new technology may bring. In order to assist in quantifying the magnitude of the problem, ECA does believe that a comprehensive, open and centralised reporting system should be available to the crews. This would facilitate correct reporting and allow monitoring of fume events at European level.

Cabin air contamination by chemicals from the engine oil is a known problem, but solutions do exist: improved training, procedures and reporting could help mitigate the risk. At the same time, ECA calls for further development of new technologies that can assist in further reducing the occurrence and effects of fume events.  You can read more in our position paper.