Vapour trails from tailcone area of jets
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?