A380CGN From Germany, joined May 2006, 21 posts, RR: 0 Posted (7 years 4 months 1 week 5 days 20 hours ago) and read 5768 times:
yesterday I was flying with 4U from CGN to VIE on an A319 and I noticed something I have never seen before and I don't know what it is: While the aircraft was on ground some sort of thick white smoke (which looked like evaporating dry ice) was constantly streaming out of the air conditioning outlets over the windows and over the overhead bins (but not out of the overhead air conditioning nozzles; only over the windows and over the bins). I held my hand in the smoke and noticed that it was pretty frosty. When the engines were started the smoke began streaming out more fast and when the engines spooled up for taxi there was even more smoke coming out. Only when we took off the smoke stopped.
As the F/As were quite busy I couldn't ask them about it but maybe you can help me...?
Thanx in advance for your answers
Xjramper From United States of America, joined Dec 2003, 2436 posts, RR: 51 Reply 2, posted (7 years 4 months 1 week 5 days 20 hours ago) and read 5760 times:
Even when its a little bit hot out, that is the way the air conditioning works until it is in the air. Once airborne it uses the air at altitude to a/c the aircraft. I don't know how the A/C works, but perhaps MEL or someone could explain it better while the aircraft is on the ground.
The only difference on the ground is the APU provides the input air to the air cycle machines instead of the engine bleeds.
This "smoke" is definitely water vapor. It's pretty common on the A319/320/321 family while it's on the ground. I don't know why, but If I had to make a bet, it would be because the APU can't cool the air as much as the engines can, so water vapor that has frozen up during the flight melts when it lands and you see it entering the air stream.
N8076U From United States of America, joined Jun 2006, 425 posts, RR: 9 Reply 7, posted (7 years 4 months 1 week 5 days 17 hours ago) and read 5704 times:
I remember when we were almost done with a C-check on an A320, they'd do a pressurization and pack operational/leak check, and you'd get that "white smoke" condensation from the vents then as well, even in a not so warm or humid environment at SFO.
N600RR From United States of America, joined Feb 2006, 171 posts, RR: 0 Reply 9, posted (7 years 4 months 1 week 5 days 13 hours ago) and read 5674 times:
Quoting Bri2k1 (Reply 3): This "smoke" is definitely water vapor. It's pretty common on the A319/320/321 family while it's on the ground.
...it happened in my Toyota truck yesterday morning.
Quoting Avioniker (Reply 4): Before the new air cycle machines and water separators came into being I used to be able to make it snow in the cabin on a nice June Orlando afternoon.
AAAhhhhhhhhh the good old days...
Would have liked to see that! Was it hard to do, or did you
just turn the a/c on when it was very humid?
"And the fluffy white lines that the airplane leaves behind are drifting right in front of the waning of the moon" -Cake
HAWK21M From India, joined Jan 2001, 31450 posts, RR: 57 Reply 11, posted (7 years 4 months 1 week 5 days 8 hours ago) and read 5639 times:
Thats caused by Water Vapour in the Conditioned Air.
The Packs have Water Seperators/Water Extractors in the System.Sometimes due to Coalaser bag blockage or Defective components,if the Water is not properly seperated from the Conditioned Air,this type of Smoky effect arises.
The Warmer outside Temperature contributes to the effect too.
Matt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4 Reply 13, posted (7 years 4 months 1 week 5 days 6 hours ago) and read 5621 times:
happens on our 340's often!
i remember being sat on the ground at the gate at JFK last october, there was a huge storm going on outside and it happened to us then, my friend who i was travelling with turned to me and said "isn't it great how they do that? i remember when the hosties used to walk up and down the aisle spraying the pesticides, now they just do it through the vent system"
A380CGN From Germany, joined May 2006, 21 posts, RR: 0 Reply 15, posted (7 years 4 months 1 week 5 days 2 hours ago) and read 5595 times:
thanks a lot for your answers! I already thought, that it was nothing to worry about but I just hadn't seen this before. Thanks again.
Quoting Musapapaya (Reply 8): Hey there!
How was your flight then? Was it nice one? I am a supporter of 4U!
Yeah, it was quite nice. I did that as a day-trip. In the morning I flew on the D-AKNR with the former US-Airways interior and on the way back it was the brand new D-AGWA. The seat pitch is quite narrow but for me it's okay.
Zeke From Hong Kong, joined Dec 2006, 8243 posts, RR: 74 Reply 16, posted (7 years 4 months 1 week 5 days 2 hours ago) and read 5588 times:
Quoting Bri2k1 (Reply 3): This "smoke" is definitely water vapor. It's pretty common on the A319/320/321 family while it's on the ground. I don't know why, but If I had to make a bet, it would be because the APU can't cool the air as much as the engines can, so water vapor that has frozen up during the flight melts when it lands and you see it entering the air stream.
Packs fed by the APU or high pressure external bleed are on high flow on the ground regardless of the setting on the overhead panel, with the engines supplying the bleed the pack flow reverts back to the setting on the overhead panel, usually "norm".
The condensation is also a function of the air that is in the cabin at the time, usual only to see this at the start of a flight, at the end of a flight when the environment inside the cabin stabilised during the flight you will not see the marked change in relative humidity between the air in the cabin and that being supplied by the packs.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
TristarSteve From Sweden, joined Nov 2005, 3855 posts, RR: 34 Reply 17, posted (7 years 4 months 1 week 4 days 20 hours ago) and read 5549 times:
The good old Vickers VC10 had godfrey blowers instead of packs. These worked well but were not very good at extracting the water.
On a descent into BAH at night where it is 30degC and 100% humidity ( yes I mean 100%, you needed windscreen wipers on to drive your car!), when the aircraft pitches nose up on finals the last four seat rows of pax get a shower!. You only sit there once!
N231YE From , joined Dec 1969, posts, RR: Reply 18, posted (7 years 4 months 1 week 4 days 15 hours ago) and read 5522 times:
I've noticed it on Avro RJ85's, coming out of the vents above the windows. Interestingly enough, while many A.Netters are talking about APU's and engine bleed air, the Avro that I experienced this on was hooked up to a ground mounted air-conditioning unit.
HAWK21M From India, joined Jan 2001, 31450 posts, RR: 57 Reply 20, posted (7 years 4 months 1 week 4 days 9 hours ago) and read 5494 times:
On the B737 Freighters,its common to notice this Smoke effect on Ground.
With The Main Deck lined with Smoke picups leading to Photoelectric type Smoke Detectors.Often the Thought is when would a Smoke Warning Illuminate,Luckily the Fogged Air does not continue to the Detectors as smoke would but the thought is always there.
Bri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4 Reply 21, posted (7 years 4 months 1 week 1 day 6 hours ago) and read 5397 times:
I rode on a UA 744 today and it there was so much mist, one passenger called it the "halloween flight." I took a short video. I'll see if it can get posted on another aviation forum which allows videos instead of just photos and provide a link here.
Bri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4 Reply 23, posted (7 years 4 months 1 week 1 day 2 hours ago) and read 5373 times:
It was only on the ground.
They tried to start number 4 engine first, but the start valve would not open. The entire time the packs were running from the APU, it was just pouring out of the vents. We had to wait a while for a mech to manually open the start valve. As soon as a couple engines were running and the packs were running from bleed air, it instantly stopped misting. I'm talking now. This is consistent with all of my previous observations and is the reason I'm skeptical about the explanation given for why it happens on the ground but not in flight.
Strangely, there was no air coming out of the directional nozzles in the overheads until about half way through the 2-1/2 hour flight (ORD-DEN). Somewhere over Nebraska, they all of a sudden came on full bore. When we got to DEN there was a ground hold due to lightning and we had to wait about 25 minutes before we could be marshalled into the gate. Because of the delay, I had to rush off the plane and didn't get a chance to ask about it. When we got to DEN, which was clearly more humid than ORD on account of the thunderstorm, the mist did not start back up. I didn't see if the plane was hooked up to a ground-based air source. I know the same plane was going to continue to SFO a couple hours later, but they could have run the APU the whole time I suppose.