Vapour trails from tailcone area of jets

[RAD_ALT_ALIVE]

Gday.

I thought I’d pose this question as a result of an article I saw today - an article that lost credibility because it was suggesting the presence of ’chemtrails’ yet again.

What are, or what causes, the thin vapour trails that appear to originate from the tailcone area of high level jets.

From close up (within 2000 ft) it always looked to me like some fluid coming from the rear-most drain masts. The article I referred to had a pic of a B744 from quite a distance away and the ‘fifth’ trail was quite distinct, making me doubt my first suspicion.

In the B744’s case, it can’t be the APU because, from memory, its APU can’t be used inflight.

Can anyone help me out please?

[dixi188]

Wash basin drains in the toilets and galleys go overboard through a heated drain mast.

Flying over the Med one day, a B737 ahead and above us had a faint contrail fron the APU. Transmitted over the radio "Forgot to turn off your APU?". About 10 seconds later the contrail stopped.
Of course there are times when the APU maybe required on a twin, ie. one engine generator inop.

[TEEEJ]

The vast majority of the trails as already highlighted is grey waste water via the heated drain masts under the fuselage. This chemtrail believer in the US (Wyoming) regularly captures the grey waste water jettisons to delude his followers. He is too far down the conspiracy rabbit hole to reason with.

The footage due to the lighting highlights the grey waste water trail coming from the belly. Most filming gives the impression that it is emanating from the tail cone area.

Boeing 747

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Boeing 747

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Airbus A380

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He has other examples on his YT Channel.

https://www.youtube.com/channel/UCsenUAiQ5K-yW0t5IZLjUqw/videos

You can see the staining under the belly in the following image links.

https://www.airliners.net/photo/Air-France/Boeing-747-428M/1127179/L

https://www.airliners.net/photo/Thai-Airways-International/Airbus-A340-642/1099785/L

[TEEEJ]

Some inflight images.

http://www.airliners.net/photo/0590207/L/

http://www.airliners.net/photo/Lloyd-Aereo-Boliviano/Boeing-767-3P6-ER/0916934/L/

[misd-agin]

If you're just in trail of a plane you can see when the sink or drains are utilized. The right sun angle and positioning helps to see it. Less common, I've only seen it once or twice in 25,000+ hours, is seeing the condensation cloud from lift being generated at altitude. I saw it once from the horizontal stabilizers of a SW 737 1,000' above us heading the same degree. They were up sun of us and barely skimming a very thin cirrus layer. In this case the 'lift' cloud was on the bottom side of the stabilizer. Memorable to see when you've only seen it once.

[RAD_ALT_ALIVE]

Thanks for the replies. Much obliged.

[misd-agin]

From a distance it looks like it's coming from the tail cone. If you get closer you can see that it's coming from a drain mast.