Hello All,I've often seen contrails emanating from the tail of an aircraft;http://www.airliners.net/open.file/981369/L/http://www.airliners.net/open.file/590207/L/I've seen particularly large ones once or twice usually coming out of Airbus aircraft. Is it cabin air or maybe a running APU?Many Thanks for any information.Paul :-)

Alas, Cannot say for sure. But one thing I do observe, is that the photos (especially the first one) looks somewhat doctored. APU shouldn't be running at all during in-flight operations (I wouldn't think).Tom

The Concorde has a low speed and high AOA Condensation clowd like that. Maybe for some reason(really high humidity?) It happened on the 747 too. He is obviously below 10,000 or cleared to land because his landing lights are on.

"Seen with a fifth contrail courtesy of the galley and toilet sinks draining out via the rear mast drain."

>The Concorde has a low speed and high AOA Condensation clowd>like that. Maybe for some reason(really high humidity?) It>happened on the 747 too. He is obviously below 10,000 or>cleared to land because his landing lights are on.The caption on the photo states that he is above FL270 and climbing.C McCarthy