B777 single trail question

[HEATHROW DIRECTOR]

I spend a great deal of time watching aircraft fly over my house so I am familiar with contrails and similar phenomena. I have just watched a BA B777 at around FL100 inbound to Heathrow issuing a single"contrail" from the tail. Nothing was coming from the engines. It obviously was not anything unusual as the aircraft joined the hold for Heathrow along with other traffic but I have never seen that before.

I'm sure someone knows what it was and I would be glad to know. Thanks.

[763 jock]

Water from the galley drain mast.

[Agaricus bisporus]

Of course that's what they want you to think. The enlightened know it's really this. Be very afraid you might choke yourself laughing.

Chemtrail Central

[HEATHROW DIRECTOR]

Of course my first thought was Chemtrail from a cunningly disguised secret military craft!

[5LY]

Not all contrails are the same. Sometimes it's moisture in the fuel which gives you a trail behind each engine and sometimes it's aerodynamic. The pressure drop over the wing causes cooling and you get condensation of moisture into visible cloud. You've seen this on takeoff when you have a very small temp./dewpoint spread and you get a mist over the wing. That's what I suggest you were seeing.

[HEATHROW DIRECTOR]

5LY. Seen it many times from wingtips but this was from the tail. I imagine 763 Jock was right.

[crwkunt roll]

I've notice many jets at altitude also have a single trail coming from the tail.

[FlightPathOBN]

Has to be a chemtrail...isnt that how the Royals keep the subjects complacent?

[misd-agin]

Watched contrails from drain masts while following guys on the NATS.

Contrail might be too 'big' a word. Water mist.

Water/lav leaks, hydraulic leaks, etc, etc, run along the fuselage until they reach the magenta line eraser(most obvious on 757 APU exhausts) at which point the airflow separates from the fuselage.

[HEATHROW DIRECTOR]

OK folks. Many thanks for the input. Yes, "contrail" was a poor description but it was all I could think of and I had never seen the phenomena before.

[Jetjock330]

One fine day head 6500nm south to "downunder opera house city", in a A340-600, we had the oppostition over take us in a B777-300ER leaving a single contrail too, coming from off center, on the left side of the tail cone. I managed to sneak a few pictures in and saw the APU inlet door left side was open, thus creating I believe the excuse for a contrail off center. It turns out that they were running the APU due to a generator failure.

[sb_sfo]

jetjock330

You sure the APU inlet door was on the left?

[marianoberna]

Conspiranoia!

Chemtrails i tell you!

[Jetjock330]

Sb SDO,
Quite right you are in asking, outlet is left and inlet is slight right of top side of tail cone.

I will look at it tomorrow on the walk around