Image shows plane smoke experiment from 1974, not evidence of 'chemtrails' | Fact check

The claim: Post implies images of smoke trailing plane are evidence of ‘chemtrails’

A Sept. 17 Facebook post (direct link, archive link) includes multiple images of an airplane leaving several white trails in the sky.

“Next time they tell you ‘It's just contrails produced by engine exhaust, you're a conspiracy theorist," reads the text in the post. “If they have any logical sense make sure to show them these pictures.”

Some social media users took the post as evidence of “chemtrails” or other nefarious government activity.

“The wind blows these chemtrails all over,” one Facebook user commented. “If u think the government isn’t messing with the weather u r very ignorant (sic).”

“Wake up people,” wrote another social media user. “Contrails don't last for hours and leave a cross checkerboard look across the sky. They should evaporate.”

The post was shared more than 2,000 times in 10 days.

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Our rating: Missing context

Multiple elements of the implied claim here are false. The trails seen in the photo were created by smoke machines as part of a study of the air patterns that form in an airplane’s wake. Experts have repeatedly debunked the "chemtrails" conspiracy theory.

Photo shows airplane using smoke machines during flight study

The photo used in the post was originally taken in 1974 and shared by NASA’s Dryden Flight Research Center, which has since been renamed the Armstrong Flight Research Center.

The image shows a Boeing 747 jetliner that was used as part of a study on trailing vortices, the “invisible flow of spiraling air that trails from the wings of large aircraft,” according to the flight center’s website.

The aircraft had six smoke generators under its wings in order to help visualize the air patterns that formed during the test flights.

The purpose of the experiment was to “test different configurations and mechanical devices on the 747 that could be used to break up or lessen the strength of the vortices,” reads the center’s website. “The results of the tests could lead to shorter spacing between landings and takeoffs, which, in turn, could alleviate air-traffic congestion.”

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The post alludes to the chemtrails conspiracy theory, which claims the white trails left by airplanes in the sky are "chemtrails," toxic chemicals supposedly added to the atmosphere by governments or other nefarious actors.

Scientists and airplane pilots say the claim is baseless. Claims purporting to prove chemtrails exist have been repeatedly debunked by USA TODAY and other fact-checkers.

Reuters also debunked this claim.

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This article originally appeared on USA TODAY: Image shows plane trailing smoke, not 'chemtrails' | Fact check