Hey everyone !! i dont know if this is the right forum to ask this in but you people are after all doing the 744 so maybe u have a clue about what this might be :(.On some pics on airliners.net ive seen a 5 contrail coming out from the 744 on some pics ive never understood if its the APU or if it is fifth contrail courtesy of the galley and toilet sinks draining out via the rear mast drain. If someone could clear this up for me i would be very very happy becuse it has been bugging me for very long.Could it be they use it only during decent?? for air conditioning or something??. Also is this something only happening on the 744??.Here is some pics of what im talking about.http://www.airliners.net/open.file/456557/L/ http://www.airliners.net/open.file/765736/L/http://www.airliners.net/open.file/208678/L/ Best regards: Alex

As far as I recall a long discussion somwhere else on this subject it is not from the APU. If you look at some other pictures you can see that this 5-th contrail doesn't originate at the tail of the aircraft (where APU is) but is slightly off center, on one side of the fuselage. I think the consensus was that it was water dumping from the bathrooms/galley. Also it is a sporadic event - you won't see this 5-th contrail all the time.Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2

The second picture of yours http://www.airliners.net/open.file/765736/LIs showing that it comes from the bottom of the fuselage just in front of the wings.Teeloo

After taking a look at some of the Tec manuals I have on the 747-400, were the 5th contrail is coming from is the same spot as the Potable Water connections. So the answer of it being water is more then likly correct. Al Stallbaumerhttp://fs2crew.com/linepilot.jpghttp://www.precisionmanuals.com/images/forum/ng_driver.jpg

Ok, here's a related story for you: I am, by profession, a physicist employed at a small liberal arts college. About 10 years ago a local fellow called the department to report that he found a meteorite in his yard. He said he heard a crash in his backyeard and went out to find a small crater and this funny rock in it. I immediately told him to bring it on in so we could check it out and report it to the proper investigators. Well, when he arrived he said he had to rush over as he was keeeping the meteorite in his freezer. Puzzled, I said let me look at it. Sure enough, his "meteorite" was about 8" inches in diameter with that distinctive blue color and wonderful odor. I explained to him the nature of jet travel at which point he promptly disposed of his "meteorite". Mike

I think the 727 was notorious for these "meteorites" building up in the tail area then dropping their big blue package to earth. Please keep your kids away from "Blue Snow Cones". ;)BobKMEM

a chemtrail :-lol