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Joshu
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What Is Being Released From This At 737?

Wed Jul 17, 2013 12:47 pm

Hey all! On short final at BWI, N174AT was trailing this about 50 feet AGL. What is it?

http://www.flickr.com/photos/50407434@N02/9308170712/

Thanks!
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Dreadnought
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 2:13 pm

Now we know one way how Airtran keeps their maintenance costs so low... 
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yeelep
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 2:51 pm

It's gray water from the aft galley/lavs.
 
ArmitageShanks
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 3:05 pm

Quoting yeelep (Reply 2):
It's gray water from the aft galley/lavs.

Does it just vent when water is used or does it have to reach a certain level in some tank then its pumped out? Does it ever freeze?
 
vikkyvik
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 3:59 pm

Quoting ArmitageShanks (Reply 3):
Does it just vent when water is used or does it have to reach a certain level in some tank then its pumped out? Does it ever freeze?

More importantly, who does it land on?  
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SAAFNAV
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 4:45 pm

Quoting ArmitageShanks (Reply 3):

Does it just vent when water is used or does it have to reach a certain level in some tank then its pumped out? Does it ever freeze?

Drainage masts for water are probably heated to prevent icing.
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yeelep
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 5:37 pm

Quoting ArmitageShanks (Reply 3):
Does it just vent when water is used or does it have to reach a certain level in some tank then its pumped out? Does it ever freeze?

The 737NG does not have a tank, it drains straight from the source to the mast. The only plane that I'm aware of that stores its grey water is the 787, it stores it in the waste tank and doesn't drain overboard. The water doesn't freeze because as SAAFNAV pointed out, the drain mast is heated.
 
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 6:27 pm

Quoting ArmitageShanks (Reply 3):
Does it just vent when water is used or does it have to reach a certain level in some tank then its pumped out? Does it ever freeze?

Older aircraft were just pipes leading overboard. In flight you can hear air hissing down the drain.
Newer aircraft sometimes have devices to stop the airleak.
As already stated B787 has no masts, just a great big toilet waste tank.
B777 has small holding devices that store the waste water in the drain pipe until an amount is there, then a pressure switch opens the valve and it all drains out.
Airbus aircraft have small float operated valves in every toilet and galley. These stop the air leaking until some liquid opens the float valve.
 
AA737-823
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 8:11 pm

Quoting JOshu (Thread starter):
At 737?

Heads up, the two-letter identifier for AirTran is FL, not At...

Quoting yeelep (Reply 2):
It's gray water from the aft galley/lavs.

As the AirTran 737s do not have aft galleys, this is lavatory sink drain water. The question is, who was using the aft lavatory sink so close to the ground!?!?

Quoting SAAFNAV (Reply 5):
Drainage masts for water are probably heated to prevent icing.

Indeed; once the airplane is in air mode, the drain mast heat activates. Drain mast heat circuit breakers must be pulled before maintenance puts the airplane into air mode artificially, otherwise, the masts will start smoking. They get VERY hot.

Quoting Tristarsteve (Reply 7):
As already stated B787 has no masts, just a great big toilet waste tank.

Well, yes, but ALL airliners have toilet waste tanks. This liquid isn't coming from a toilet, but a sink/basin. Important distinction.
 
KELPkid
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RE: What Is Being Released From This At 737?

Wed Jul 17, 2013 8:42 pm

Quoting AA737-823 (Reply 8):
As the AirTran 737s do not have aft galleys, this is lavatory sink drain water. The question is, who was using the aft lavatory sink so close to the ground!?!?

At 50' AGL, the pilot flying is probably beginning the flare. I'm sure a little bit of water that was trapped in the pipes gets freed up by the attitude change   NO one should be in the lav at this portion of the flight...
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Joshu
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RE: What Is Being Released From This At 737?

Fri Jul 19, 2013 2:14 am

Quoting AA737-823 (Reply 8):
Heads up, the two-letter identifier for AirTran is FL, not At...

Ha! True...I was thinking about the registration as I edited the pic...totally forgot it was FL.

Anyway, he was only a few seconds away from touchdown and I was surprised to see it discharged so low considering it was Directly over Dorsey rd. when this was taken...just 3-4 seconds before flaring.
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JAAlbert
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RE: What Is Being Released From This At 737?

Mon Jul 22, 2013 2:49 am

So what, exactly, is grey water? Is this the waste from the toilets or the sinks in the galley and lavatories?
 
yeelep
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RE: What Is Being Released From This At 737?

Mon Jul 22, 2013 12:23 pm

Quoting JAAlbert (Reply 11):

Its water from the lav. sinks and galley drains.
 
AA737-823
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RE: What Is Being Released From This At 737?

Tue Jul 23, 2013 8:17 am

Quoting JAAlbert (Reply 11):
Is this the waste from the toilets

Okay, once again, human waste is NOT DUMPED OVERBOARD.
I don't know why people insist on believing otherwise.
 
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HAWK21M
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RE: What Is Being Released From This At 737?

Tue Jul 23, 2013 10:09 am

Grey water from the aft galley, passing thru a drain mast that is heated to prevent the water from freezing.
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