Some people point out that there "appears" to be many visible chemtrails, to the point that they criscross the sky in a lattice sometimes. But if true, what planes exactly are.doing this? Wouldn't experienced airline pilots pick up on something of that magnitude happening in our skies? Some people also point out that there are many more vapor trails in the sky than there were, say 30 years ago. And I've kind of noticed that too. However, the explanation that I offer to the conspiracy theorists is that over time aviation fuels have improved a bit, which required reformulating them somewhat, and which may produce more vapor than earlier types of fuel. I remember back in the '80s that airports smelled freaking nasty because of the exhaust coming from big jets taking off and landing. I don't notice that so much anymore which lends even more credibility to the idea that aviation fuels have changed over the years.