Contrail-Mapping Could Reduce Harmful Effects By Half


The virtual explosion of applications for using artificial intelligence (AI) could soon include minimizing aircraft condensation trails, the cloud-like results of high-altitude moisture meeting the disruptive churning of jet engines and/or aircraft wake turbulence. “Contrails” (not to be confused with the controversial concept known as “chemtrails”) have been shown to contribute as much as 35% of aviation’s climate impact by creating clouds that trap greenhouse gases that otherwise would dissipate into space.

According to Britannica, “A contrail forms when water vapor produced by the combustion of fuel in airplane engines condenses upon soot particles or sulfur aerosols in the plane’s exhaust. When the ambient relative humidity is high, the resulting ice-crystal plume may last several hours.” And not all contrails are harmful. Jill Blickstein, VP of sustainability at American Airlines, told CBS, “A contrail could form and then just dissipate, but the contrails that persist can be very warming.”

Based on a study involving American, Google and the Bill Gates-created Breakthrough Energy organization, AI-generated contrail forecast maps could enable pilots to alter course and/or altitude and reduce the overall greenhouse effect of contrails by as much as half, worldwide. The maps are generated using satellite imagery, weather data and flight path information to identify which flights are most likely to generate the worst contrails.

More than 70 test flights in the first half of last year showed that predictions of contrail-vulnerable conditions could enable pilots to make slight adjustments in course or altitude. Blickstein said a change of as little as 2,000 feet up or down could do the trick. “What the test showed is that you could use the predictions to avoid creating a contrail,” she said.

It’s a technique that was well known to American F-86 Sabrejet pilots during the Korean War, but for a different reason. For a fighter pilot, altitude is the “high ground” when entering a combat zone—the higher the better. But generating contrails alerted enemy pilots from miles away. So while still in safe airspace, the Sabre pilots would climb until they started generating contrails, then reduce altitude until the telltale plumes dissipated.

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Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.


  1. Oh good grief. One volcanic eruption probably has a greater effect than the entire history of contrails. I suggest tin foil caps for those who worry about such things. Common sense is no longer common.

    • So, paraphrasing one of the science/climate change deniers biggest lies I see.
      “Extraordinary claims require extraordinary evidence”. -Carl Sagan-
      In other words, show your work.
      Provide demonstrable searchable references and a bibliography.
      BTW there is not, and never has been, anything that remotely resembles “common sense”.
      That is another 19th-century piece of nonsense. Thanks again Victorians.

    • Much ignorance is ascribed to “common sense”, Kent. “Common sense” tells us that after 10 consecutive “heads”, the odds of a coin flipping “tails” is much higher. Your assertion about volcanic eruptions vs. contrails has been studied. Do your homework before you run out of your own tin foil.

    • Hi, Kent! As ever, a very forceful comment from you! While it may or may not be true that volcanic eruptions have more effect that contrails on climate change (I don’t know whether that is the case or not), it sure would be great to avoid negatively affecting the climate whenever we can, wouldn’t it? I can only imagine that if someone were dumping garbage on your front lawn, you’d want them to stop even though their doing so would be less damaging to your property than, say, a hurricane!

      As much as we’d like to believe otherwise, there’s room for improvement in everything we do, whether that means reducing the effect of contrails or being more civil in our public commentary on aviation news websites.

      Have a great day!

  2. Then deviation around the area of contrails will burn more fuel, more greenhouse gases, oh well, since the “science is settled”. Don’t know about where you are from but clouds in the day time cool the surface, clouds at night keep in the heat. Maybe just no contrails at night would be even better.

  3. And what about the methane from cows and other live stocks. This continues to be a contributing factor.

    Guess I’ll just have to eat more of them. One way to reduce their population. )

  4. Seems like a sensible way to manage this aspect of aircraft emissions. We’ll see if it has reasonable impact, given potential trade-offs in efficiency, but nonetheless very little, if any, downside for trying.

  5. As an airline Captain who flies international, heavy aircraft I can tell you 2000 feet of difference in optimum altitude will burn much more fuel on a long flight. Just so you know where I’m coming from, I don’t believe in this “global warming bunk”. That being said, show me the data where my burning an extra 1200 to 2000 pounds of fuel (carbon producing) would make more difference than not leaving a contrail. This is another typical hair on fire response of “We have got to do something or we’re all going to die!” without any real thought going into it.

  6. As a young engineer with a large defense contractor in the ’80s I made a study of contrail forecasting and suppression for stealth aircraft “low observables”. It is straight forward to predict if contrails will form and if they will be persistent or rapidly dissipate. This is basic engineering analysis combining a mass & energy balance with vapor liquid equilibrium along the lines of psychrometry for HVAC or temperature dewpoint spread that pilots use. The difference is that it is calculated in the exhaust plume as the hot moist exhaust mixes with the cold dry atmosphere. So, the science and practice of contrail forecasting has been known for decades. It isn’t rocket science (I’ve done that too) and it doesn’t require AI. And as has been noted in the comments 1) it is easily managed empirically (fly lower when they appear) and 2) it will cost way more fuel to fly lower to avoid them. The comment that they trap greenhouse gases that would otherwise dissipate into space is patently false. The primary GHG of interest is CO2 and it is the least likely to dissipate into space which is why the atmosphere of Mars with its low gravity and lack of magnetic field is 96% CO2. The effect of contrails is like any other cloud (which is all a contrail is) and that is to block infrared thermal radiation from dissipating heat into space. I haven’t done the detailed thermal analysis but my intuition having spent decades doing detailed thermal analysis is that the topside reflection of solar energy from the contrail away from earth ought to roughly balance the bottom side reflection of heat back to earth.

    • Refreshing to have someone with real expertise.

      My guess is that there is a high correlation between those who take their private jets to Dravos and those who want to impose this on the airlines.

      Lower altitudes mean lower efficiency and the consumption of more fuel.

      It is hard to believe that the tiny coverage created by contrails compared to cloud cover has any measurable impact.

      Of course when we have an electric 847 all of this will disappear…

  7. That will “work” just fine until the flight crew has to climb or descend for icing or turbulence or winds. Total BS. Solar activity controls our climate not us. “Niriv Shaviv, chairman of the university’s physics department, says that his research and that of colleagues, suggests that rising CO2 levels, while hardly insignificant, play only a minor role compared to the influence of the sun and cosmic radiation on the earth’s climate. “ This world renowned astrophysicist was written about in Forbes a few years ago. You can’t find the article on Forbes anymore because the fear mongers took the article down. He is a very respected scientist and essentially says we are not in control , the sun is.

      • Nir Joseph Shaviv is an Israeli‐American physics professor. He is professor at the Racah Institute of Physics of the Hebrew University of Jerusalem. That’s what the google said. And Flyer Don I’m not sure the university of Trump could spell Fisic’s

  8. We live over one of the main “jet streams” for East West traffic, and with con trails, can count the number in the sky at 10,000 metres and above some day — my record is 47.
    Some days, estimate seven a month, the contrails form clouds, which cross and recross as they are added too.
    During the Covid lockdown, (three week ban on air travel was the longest over us) it took at least four days for normal clouds and skys to reappear.
    Air industry needs to sort it out voluntarily using initiatives like this, or face regulation it will not like.

  9. A mentor of mine was once asked whether a panel on the health effects of a potent toxic substance was “balanced.” She replied, “It is very well balanced. For every panel member who knows what they are talking about, there is another member who does not.”

    That is how I see the comment section on AvWeb. The willingness of so many pilots (and whomever else comments here) to offer their strongly held and utterly unsupported opinions is nothing short of breathtaking. Apparently, a moment of thought by a pilot is a better representation of reality than long study by actual experts.

  10. It’s just a study…maybe it fails or maybe it produces some positive results, but it’s just a study.

  11. First off. Do humans have an impact on global warming? YES Easy to prove. On a summer day take off your shoes and stand on the grass for a few, Now walk over to some blacktop and stand there. Second off. What can we do about it? Simple LEAVE the planet it will go back to the way it was. We have been screwing up this planet since we got here and making airplanes fly in a zigzag will not make an impact on what we have already done.

  12. Imagine a world where we gave respectful consideration for each others point of view. Instead we use language that demeans the points of view that are different than ours. The truth of the matter is that most everything that is studied and claimed to be true and defended and argued. Why can’t we do that civilly?

    I look at the situation we’re in as pollution. And that most can agree on.

  13. The solution is to stop publishing the research if people who struggled to get a D in high school physics.

  14. Radiation in, radiation out. Hod does this relate to the “science based” proposals to alleviate global warming by intentionally creating high altitude particulate barriers?

  15. One more “scientific” finding to support the left narrative. We need to get these morons out of positions of authority. Same thing with the unleaded fuel…

  16. Once again lets ignore the inconvenient fact that, CO2 to a plant = O2 to an animal. Therefore, more CO2 (at least to a point) = healthier, faster growing plants. Check out Biosphere2 near Tucson AZ.

    A quick google search says Methane is 80X worse than CO2, mostly because it sticks around for 20 YEARS! Animals flatulate methane.

    My brothers research, 40 years ago and supported by a PBS program I watched 50 years ago, concluded that most of the energy humans consume goes towards putting meat on the table. Including fuel /energy used to farm, (grow animal food), transport, refrigerate (preserve) and cook said meat. He also concluded that, at the time, the US would be energy independent if we’d all just stop eating meat. Heresy, i know.

    I say this, suggesting that studies like these could be used to support an agenda.

  17. Given how completely off-the-wall the comments have gotten recently, I have to wonder whether the only restraint on commenters was the fact that Paul B. might chime in and scold someone for writing nonsense.

    Oh well.

  18. “by creating clouds that trap greenhouse gases that otherwise would dissipate into space”

    Wrong physics. They cause global warming by reflecting energy that would otherwise be radiated into space.