Editor’s note: Following is the U.S. military’s response to citizen concerns over suspicious aircraft contrails, often dubbed “chemtrails.”
The Environmental Protection Agency, with the assistance of NASA Glenn Research Center’s Ultra-Efficient Engine Technology Program, National Oceanic and Atmospheric Administration, and the Federal Aviation Administration, released a contrail fact sheet in September of last year in response to public inquiries.
“Contrails have been a normal effect of jet aviation since its earliest days,” the report states. “Persistent contrails are composed of water naturally present along the aircraft flight path.”
While they do not pose health risks, contrails affect the cloudiness of the atmosphere and may affect atmospheric temperature and climate, the report states. The entire document may be viewed online.
“Jet aircraft contrails are an entirely normal occurrence of high-altitude flight, and result from an aircraft engine emitting tiny particles that serve as condensation nuclei,” said Kenneth Petche, an environmental engineer with the U.S. Environmental Protection Agency. “High-altitude water vapor collects on these particles, crystallizes, in turn creating streaks of frozen water vapor, otherwise known as contrails from airplanes operating at high altitudes.”
The Yosemite area is in the center of a triangle framed by numerous airports and military bases, said Capt. Thomas Crossen from Travis Air Force Base in Fairfield. Military jets are only a small portion of the aircraft in the sky, Crossen said. The planes leaving trails could be commercial flights, private flights or civilian aircraft leaving or arriving at any of the local airports.
Airplanes that fly at high altitudes and at high speeds always leave some sort of a vapor behind them, Crossen said.
The Air National Guard based in Fresno is not responsible for the trails in the Central Valley, said Capt. Chuck Pratt.
“We don’t have aircraft that does that,” Pratt said. “Our jets cannot leave any type of contrail like that. We don’t even fly over Oakhurst.”
The Fresno base flies only F-16s, and they fly them only over the desert, he said.
Aircraft leaving from or arriving to Fresno Yosemite International Airport are not responsible either, said John Manuszak, the air traffic manager. Their flights do not generally fly high enough, above freezing temperatures, to leave significant contrails, he said. Air traffic control in Fresno is unable to track aircraft in the Oakhurst area due to radar restrictions, he said.
“Not to be overly dismissive, but the conspiracy theories on this are so convoluted,” said Capt. Tadd Sholtis from Travis Air Force Base. “I know that there are people out there that are convinced of this thing; but this is the way it is and it’s not the way that they think.”
Lance Lindsay is a freelance reporter based in Madera County, California.