The fact is that contrails do collect in the sky to produce cirrus blankets over an otherwise clear blue sky. The sky where I live is regularly clouded over by contrail cirrus blankets even though there is no major airport for over 100 miles. Granted, most of the conspiracy buffs have little meteorological education, but you cannot simply discount ALL of their concerns. Pilots that deny the consequences of airplane pollution are right on par with the conspiracy theorists - they must be crazy. Any responsible, educated, experienced pilot should be aware of the possible consequences of filling our atmosphere with airplane emissions, especially considering the ever increasing frequency at which people are taking to the skies. Nobody wants to believe that their career, hobby, or livelyhood may have negative consequences, which is why contrails are so vehemently defended on this thread. There is a lot of evidence that suggests airplane pollution may contribute significantly to a greenhouse effect, globally and regionally. This information doesn't come from half-baked conspiracy theorists, it comes from reputable scientists, whom I would trust before anyone in the airline industry when it comes to looking at reality directly with both eyes open. Changing the composition of the atmosphere is no laughing matter, and I think that is the real issue that needs to be addressed when we talk about contrails. The prevelance of contrail cloudiness is really just an indication or sign of how much pollution is being constantly delivered to the upper atmosphere. Sometimes I wonder if all the conspiracy theories are made up in order to take attention away from the only real problem with what we can see in the sky - pollution. I guess that too would be a conspiracy theory, but one that may actually make sense. Finally, to the guy(UCONNQB14) who thinks he's God's gift to golf, I have this question: Do you think that your amatuer skills are an excuse to belittle other people's values - ie. blue skies? I value blue skies, and a sense of a healthy future for myself, my kids and the Earth system that supports us all. What do you value other than money, your ego and a pointless game? I suspect that when you grow up, you'll be eating a lot of your words.