Are friend told me about oil fumes contamination he experienced during a flight. This seems to be no isolated case. This list shows several incidents of similar type over years.

“Upon initial descent there suddenly was a very strong oil smell in the cabin.” “Both pilots had red irritated eyes and gave me the impression that they were quite fatigued.” “…the pilots did confirm that there is something and that this is very likely a strong oil smell.”


"Shortly after initiating a descent, an oily smell was noticed on the flight deck, almost immediately followed by a smoke build-up in the flight deck and cabin." "during the 36 months examined (by IATA), there occurred an average of two and a half smoke events each day." "Smoke protection for passengers is not a requirement on public transport aircraft"

Now here it gets really interesting

When commercial flights began in 1958 passengers breathed in air supplied directly from the atmosphere using compressors. But this was deemed to be too expensive, so in 1962 a system was installed to draw the air from the heart of the engines — known today as “bleed” air.

Air is drawn out of the compression section of the engine and cooled. It then enters the cabin, where it mixes with recirculated air that has passed through filters designed to remove bacteria and viruses. These “recirculated air” filters do not remove any fumes or vapours from the engine. So if engine oil or hydraulic fuel leaks, because of poorly designed or faulty seals, or even over-filled tanks, toxic chemicals can contaminate the air supply.

On medical consequences the article states:

At the very least this can cause drowsiness, headaches, flu-like symptoms and nausea — the kind of symptoms that Dr Nicola Hembry, a specialist in environmental medicine, says passengers may wrongly assume have been picked up from another passenger. At worst, air can be laced with a chemical, tricresyl phosphate (TCP), an organophosphate, or other toxic mixtures of chemicals that have been linked to serious respiratory problems, memory loss, neurological illnesses and even brain damage.

It seems the coming Boeing 787 is the first airplane regarding (suddenly?) this:

In 50 of years of commercial flights, aviation has changed beyond recognition. But for all the advances in design, safety and comfort, until the launch of Boeing’s new Dreamliner (787) next year (on which air will be compressed electronically), little has been done about the fact that both passengers and crew are breathing in air that comes straight from the engines.

From aerotoxic.org

Q. How often do fume events happen? A. As there are no fume detectors

  • even on the most modern jets, it is impossible to give a figure but the UK Government works on 1 in 100 or 1 in 2000. Many aircrew say that each flight is affected.

Are those fume events a frequent occurrence and a significant health hazard?

Airplane companies know that their constructed environmental system for cabin air is flawed and seriously hazardous to pilot and passenger health, but try to play sanitary consequences and frequency of such incidents down to save costs.

Despite losing lawsuits concerning oil fumes companies state:

Aircraft manufacturer Boeing concedes there is a chance of fume events, but the company says the air on board its aircraft is “safe and healthy.”

Are there serious third-party studies from independent medical doctors who treated such passengers, studies how often these incidents happen in airliners? There seem to be quite a number of notifications and lawsuits about oil fume events (see links above). Even some pilots and flight attendants are involved in lawsuits with their companies.

Nobody seems to disagree that those fume events happen, but the airlines argue that they only happen seldomly under exceptional circumstances. Some groups though claim that those events are frequent and a significant health hazard to frequent flyers. How often do those fume events happen and are they a significant health hazard to crew and passengers?

  • 3
    @Hauser - "so often"? I would disagree - look at the number of people/flights and the number of cases. Looks like a miniscule number to me. Not only have I flown over 800 flights in the last 15 years without this ever happening to me, but I only know one person it has happened to, and they pilot a plane for a living :-)
    – Rory Alsop
    Oct 8, 2011 at 21:33
  • 1
    @Hauser I answered you as to how fumes can get into the cabin: contaminated or malfunctioning filters in the air conditioning/cleaning system (which draws its intake air from engine bleed air, which of course may contain volatile components from grease and other things in the bleed air system that the air flowed through/past). Same can happen with any air conditioning system, but as airliner systems don't draw intake air from the environment but from the engine (bypass), their intake air is probably not as clean as that for other systems. This is of course done because of the environmental
    – jwenting
    Oct 10, 2011 at 6:20
  • 1
    Unrelated question: Does anyone have any idea what "compressed electronically" might mean?
    – Oddthinking
    Oct 11, 2011 at 16:05
  • 1
    Nevermind, I found out they meant to say "electrically driven compressors". "Electronic" is not the same as "electric".
    – Oddthinking
    Oct 11, 2011 at 16:12
  • 1
    It's old, but there is too much sensationalist BS in the statements to give it a pass. From simple facts that "commercial flights began" in 1910s, not in 1958 (I know they meant B707, but it had to be qualified), to the fact that there is no fundamental difference between the systems. The air is always compressed by... compressors, the difference is only what drives those compressors. Bleed air is taken from the main compressor of the engine, well before "the heart of the engine". It's still just fresh air: it only encountered a few blades on its way....
    – Zeus
    Nov 10, 2022 at 7:02

1 Answer 1


The US Federal Aviation Administration (FAA) states:

smoke/fumes in cabin/cockpits is still a serious problem.

They explain:

Reports to air traffic, submission of Service Difficulty Reports (SDR), and several focused surveys reveal that approximately 900 smoke or fumes in the cockpit or cabin events occur annually in transport category airplanes. Many of these incidents prompted the flightcrew to declare an emergency and either divert, turn back or request priority handling to their destination.


The air carriers and operators that have experienced these situations are required to submit a report to the Federal Aviation Administration (FAA) for smoke/fumes in the aircraft.


That number 900 should be compared to the total number of flights managed by the FAA. I couldn't get that number exactly (closest I got from the FAA was "740 million enplanements on U.S. carriers each year" [Source] - but that counts once per passenger, not once per flight).

However, I did get the number of flights departing US airports: a smidgin under 10 million in 2010. [Source]

So you have a 0.009% chance (about 1 in 11,000) per flight of being subjected to smoke or other fumes - and a smaller chance that it will cause you any harm.

Within the vagaries of what "safe" means, I think this is consistent with both the versions of events being portrayed:

  • It is a serious problem for aircraft manufacturers to consider.
  • The air in aircraft is safe.
  • 1
    I haven't considered if passenger planes are more likely to have filtered air in the cabin than cargo planes.
    – Oddthinking
    Oct 11, 2011 at 15:32

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