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Topic Author
Posts: 527
Joined: Wed Feb 16, 2000 3:21 am

5th Contrail

Sun Mar 16, 2003 4:45 pm

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Photo © Derek Pedley

I have had dozens of emails on this picture to the possible cause of this 5th contrail on this AF 744 most saying the APU. But if you look at where the contrail starts I can't see it. I am no expert but would the APU be on anyway with an hour or so to go before landing?

One other email from a AC engineer says:

The AFT drain mast (there are 3 drain masts on the B747-400 (FWD, MID & AFT) which expulse the water from the lavatory and galley sinks (when you wash your hands in this airplane, the water is actually thrown directly outside!!)) These drain masts are heated at very high temp to prevent ice formation. The outside air temperature, coupled with the temperature of the drain mast must have been enough to cause the 5th contrail.

Be interesting to hear what you all think.

Kind regards

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Joined: Wed May 22, 2002 10:26 am

RE: 5th Contrail

Sun Mar 16, 2003 4:51 pm

Hi Derek

I'd have to say its from the aft drain mast too which the galley and toilet sinks drain to. Its not just dirty water that is thrown out but before landing opened bottles of Champagne and wine are poured down here, all the unused coffee etc

Etihad Girl, You're a great way to fly.
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RE: 5th Contrail

Sun Mar 16, 2003 4:53 pm

If you look at the picture closely you can clearly see that the contrail is not coming from the APU. The drain mast explanation therefore makes the most sense.
Topic Author
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RE: 5th Contrail

Sun Mar 16, 2003 5:58 pm

I like the idea of it being a "Champagne Contrail"  Smile/happy/getting dizzy

Topic Author
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RE: 5th Contrail

Tue Mar 18, 2003 6:03 pm

Another point now looking at the 6 pictures I took all with the 5th contrail over a 75 second period from first to last.

This is one hell of a lot of waste. Why is it not stored and then emptied at the end of the flight like the toilets. If it is coffee/wine and all other liquid waste, its not a nice thought thinking of is being dumped like this.

Is this common practise with all airlines or just some ?

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RE: 5th Contrail

Tue Mar 18, 2003 8:37 pm

the 5'th contrail is definately not coming out of the APU exhaust. It looks like it is coming from the rear belly of the aircraft. So I would have to say the AFT drain mast explanation is correct.
Jason Nicholls - v1images
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RE: 5th Contrail

Tue Mar 18, 2003 11:26 pm

I was wondering if the fifth contrail might be coming from the air conditioning pacts.
They can expel very warm air, and at that altitude, it might be possible to leave a contrail.
Just my thoughts.

In life, some days you are the bug..... some days you are the windshield!
aer lingus
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Joined: Sun Mar 25, 2001 6:40 pm

RE: 5th Contrail

Fri Mar 21, 2003 3:25 am

Imagine what happends if the wastes are dropped when landing! (what will be next) ????
Plane spotters and photographers like us would have ' The Real Champagne Feast' !  Smile
We would say 'OMG' if there is someone doing the You Know What in the lav after eating some Dodgy Chicken ' Nobody likes that anyway' !
So whats the story of the toilet truck?
If they dump unwanted stuff outside in flight? A funny question!

The fifth contrail is a really hard question after all!


LMFC BA Photography Team. Big grin
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