Contrail Avoidance Possible But Uses More Fuel


A small study facilitated by American Airlines and Google has shown that it’s relatively easy to cut the amount of contrails created by airliners but it comes at a fuel penalty. American supplied the aircraft for 70 flights and used software developed by Breakthrough Energy to create flight plans that avoided frozen water vapor-producing conditions. In the trial they were able to reduce contrails by 54 percent but maneuvering to avoid the contrail conditions used about 2 percent more fuel. And even though more fuel was used, the contrail avoidance might be worth it from an environmental point of view, according to the authors of the study.

“Avoiding contrails might be one of the best ways to limit aviation’s climate impact, and now we have a clear demonstration that it’s possible to do so,” said Marc Shapiro, Breakthrough Energy’s director of contrail studies. Contrails were generally considered to be a harmless byproduct of jet fuel combustion but their impact on climate change might have been underestimated. The artificial clouds trap heat in the atmosphere.

According to the Dallas Morning News, Google and Breakthrough used artificial intelligence to modify the flight plans for the 70 flights to steer clear, as much as possible, from the altitudes, weather and humidity where contrails were most likely to form. Then Google used its satellite cameras to check the results. Jill Blickenstein, American’s VP of Sustainability, said pilots played a big role in carrying out the research. “One of the main reasons that we had success is that we had a small group of pilots who were really excited about trying this,” she said, adding that others who were recruited also quickly got interested in the project.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

Other AVwebflash Articles


  1. The record number I have counted over me was 52. During lockdown it took around 2 days for all to clear, and then we got clouds like I remember from 20 years ago.

  2. So confused: I thought that the net effect of anything that blocks sunlight, over any 24 hour period, is to lower temperatures. See: “1816 the Year Without a Summer”. Cold is bad, carbon is good. ymmv.

    • Like most things, it isn’t that simple.

      During the day, clouds and contrails block incoming heat energy and have a cooling effect while at night they block the Earth’s heat energy from radiating back into space and keep the Earth warm. The rub is that incoming and outgoing energies are at different frequencies and clouds have a bigger effect on the energy the Earth radiates at night.

      If one could maximize contrails starting at sunup, generate no contrails starting at sundown, and ensure the contrails dissipated by sundown, you would get net cooling.

  3. Will AI also map out the new and numerous heading changes needed to miss the now up and down and left and right aircraft dodging contrails? Or maybe I don’t have a full understanding….probably.

  4. While flying off the US Kitty Hawk in 1981 during the Iranian Crisis, while on Gonzo Station in the Arabian Sea, we routinely received a Contrail Altitude Forecast in our preflight briefing.

    • For obvious reasons…while at altitude during ingress during a combat strike you certainly did not want the enemy to easily spot you visually. It was also imperative while flying against our sister Air Wing off the USS Nimitz during War at Sea exercises out there! At times we would fly these exercises under EmCon (emissions controlled) where the use of radar and radio transmissions were strictly prohibited and the “fight” therefore was purely visual. The fighter with the first “Tally Ho” gained a huge advantage in the ensuing dogfight.
      “Check Six!” 😉

    • This does seem like a surprising “news” story, since as you point out we’ve known for 50 years what makes contrails and how to avoid/limit making them. Plus it’s been an active topic in civil aviation for some years.

      For those interested in the topic, search for:

      • And yet, there are constant rants from the unhinged “Chemtrails” nuts, as if it’s some Eeeevil new phenomenon.

  5. “but their impact on climate change MIGHT have been underestimated.” More positive proof of global warming. Gee, I always thought it was the government spraying mind-altering chemicals.

  6. Good now all the chem trail alarmists will pipe down.

    True story: I have a switch marked “CHEMTRAILS” on my panel.

  7. What a joke! The religious climate changers are going to extremes. Jet contrails can never compete against mother nature when forming clouds. And, by the way, they are the biggest factor in causing warming. Good old water vapor can’t be beat as a “global warming” gas. If we could just eliminate that.

    • “Jet contrails can never compete against mother nature when forming clouds.”

      They don’t have to compete, they just have to push it off balance. Have you been in cruise flight, nicely trimmed, then leaned forward and have the plane start to slowly descend? It’s like that. It doesn’t take much, it doesn’t happen fast or right away, but it can continuously push things off balance. Like a bent rudder trim tab.

      And we’ve actually had a real-world experiment, so-to-speak. When all flights were ground after 9/11, contrails disappeared for a few days. It was seen that daytime temps increased (because of lack of clouds blocking sunlight), and nighttime temps dropped (because of lack of clouds blocking infrared radiation). There’s a lot of debate about how much change occurred, but their is broad agreement that contrails do affect the weather.

      Something similar occurred during the recent pandemic. The dramatic reduction in flights gave us another chance to study real-world results of removing contrails. However, the drop in other emissions from closing factories, docking cruise liners, few cars and trucks driving, etc., may muddy the data. However, scientists can (and are) studying the data to see what happened, and how and why.