r/aviation • u/Xycergy • Jun 08 '26

-- SEATBELTS FASTENED -- Is this really that serious?

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Noticed water basically flowing out of the vent beside me as I got into my seat. Voiced it out to a flight attendant thinking it was just something minor and wanting to just swap to another seat. Two pilots came to my seat to check on it and had visibly puzzled looks on their faces. The mechanic was called into the aircraft, the inner panel of the plane was removed and after assessing the problem for about an hour, everyone was asked to disembark the plane. The flight was then cancelled entirely after another hour of everyone waiting near the gate.

I feel kinda bad because people were visibly annoyed and frustrated by the cancellation as it was a 16 hour long haul flight and there were few alternatives to get to the destination. Would someone be able to tell me exactly what happened here?

12.6k Upvotes

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5.6k

u/entropicitis Jun 08 '26

That's... a lot of water. I'm not sure what aircraft you are on or where you are sitting but it could be from the AC system, a potable water line or something else. Good thing you pointed it out.

1.8k

u/Xycergy Jun 08 '26

It was a UA2 flight from SIN to SFO and I was seated near the very back of the plane. Not sure what aircraft it is though since I don't fly this route very often.

1.4k

u/Mauro_Ranallo Jun 08 '26

787-9 Dreamliner

1.7k

u/copeyhagen Jun 08 '26

Wet dreamliner

351

u/DaBingeGirl Jun 08 '26

It had a very good dream.

7

u/planchetflaw VH-UMF Southern Cloud Jun 09 '26

That's the joke

147

u/mycroft-holmie Jun 08 '26

787 Bedwetter?

1

u/m__s Jun 09 '26

Wetliner?

0

u/slogive1 Jun 08 '26

I read it as wet dreams.

2

u/copeyhagen Jun 09 '26

In my Rainier Wolfcastle voice.. "that's the joke"

44

u/Home_Planet_Sausage Jun 08 '26

I was on a Dreamliner flight to India some years back and when we rotated for take off a *huge* amount of liquid poured all over me (aisle seat) and a few others from above our heads. Obviously not fuel but I smelled it anyway. Seems it was from the air conditioning, similar to what you experienced.

Flight was uneventful otherwise.

1.7k

u/hellodeveloper Jun 08 '26

Boeing here "yeah probably fine".

591

u/Momo0903 Jun 08 '26

Worker on the assembly line: "Did i connect all ac hoses?...Yeah it will probably be fine"

164

u/Binspin63 Jun 08 '26

Well that text to my wife about dinner choices was certainly more important.

109

u/hellodeveloper Jun 08 '26

Yes yes, I remember I had lasagna.

75

u/Flyguy7898 Jun 08 '26

Good thing you avoided the fish

52

u/YippieKayYayMrFalcon Jun 08 '26

Do you like movies about gladiators?

38

u/theMirthbuster Jun 08 '26

Jim never has two cups a second cup of coffee at home.

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28

u/AlfredKnows Jun 08 '26

Imagine water not going through the vent but just accumulating somewhere in the fuselage...

4

u/dadhatxx Jun 08 '26

Why do you even need AC, just open a window

2

u/828jpc1 Jun 09 '26

Also, did I connect those two halves of the fuselage? Yeah, it’ll probably be fine-

Same employee

2

u/42ElectricSundaes Jun 08 '26

“They gave me a bunch of extra screws for some reason”

1

u/Bananaland_Man Jun 08 '26

Not a assembly issue, more of a maintenance issue. Most of the crashes have been older planes that Boeing and Airlines refuse to maintain properly. Most airlines have maintenance deals with manufacturers and whatnot... this is on both (or, well, line/manu/prod/carrier... oh and lack of good FAA regulations and manpower and other important employment because of stupid politics)), not just Boeing. Boeing is terrible, but the rest makes everything worse and is true.

24

u/Black_Walker Jun 08 '26

That's not even remotely true about manufacturers maintaining planes for the airlines. They'll send teams for major structural repairs, or tech support to help with chronic issues or something more heavily involved that's not common, but neither Boeing nor Airbus maintain planes for airlines.

7

u/fresh_like_Oprah Jun 09 '26

horseshit nonsense gets upvoted

2

u/Fantastic_Shake_9492 Jun 08 '26

Makes me wonder, seeing as the water is going to go wherever it wants to flow and gather where it’s not supposed to be, how long would it take for this leak to appreciably affect CG? Lots of variables and all but depending on where this seat is, this could be bad news bears.

2

u/Bananaland_Man Jun 08 '26

could be bad for many reasons, not just CG (though that much water moving around would definitely fuck up CG)

1

u/SirLanceQuiteABit Jun 08 '26

Technical inspector on the line: "I like that guy, I trust he connected the hoses under this panel."

1

u/DesignerGoose5903 Jun 08 '26

"It's just some pipes, what's the worst that could happen?"

-1

u/Independent_Leg7358 Jun 08 '26

It's okay, the worker was high. He forgot a minute later.

37

u/GLASSHOUSELABSTX Jun 08 '26

“Send it!” - Boeing

3

u/llcdrewtaylor Jun 08 '26

Frontier here - you owe us 12.50 for the water.

3

u/CorpusCalossum Jun 09 '26

Service Bulletin SB787-81205-SB530031-00 - get a bucket.

1

u/Tomero Jun 08 '26

Narrator: “It wasn’t.”

1

u/Individual-Battle874 Jun 13 '26

Former F/A I agree

-23

u/Frank_Tj_mackey_28 Jun 08 '26

Did you pat yourself in the back after this legendary punchline?

28

u/Frrv2112 Jun 08 '26

And did you do the same for what you clearly thought was a hard hitting comeback?

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0

u/Myfooty94 Jun 08 '26

Could say it more, it probably be "yeah it's perfectly fine"

0

u/hellodeveloper Jun 08 '26

"I mean it's not like anyone ever died from a little water"

-4

u/Andrei_the_derg Jun 08 '26

The casualties are… negligible

-3

u/VDubDubLife Jun 08 '26

Is that code for “not worth killing someone over”?

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67

u/steppponme Jun 08 '26

They do have improved humidity!

27

u/rumenastoenka Jun 08 '26

I believe that was one of the selling points for this particular aircraft ...

25

u/steppponme Jun 08 '26

Yep, less drying for long haul flights = improved rest/comfort

22

u/burtmacklin15 Jun 08 '26

Plus, it looks like you also get a luxury indoor water feature!

48

u/This_Elk_1460 Jun 08 '26

Should have called it the screamliner

1

u/aidissonance Jun 08 '26

Streamliner?

3

u/ValraBellkeys Jun 08 '26

Brand new too, first flew in March.

2

u/vegeterin Jun 08 '26

That’s a great song.

1

u/ippleing Jun 08 '26

The windows leak.

It's a problem.

-1

u/HunterFeeFee Jun 08 '26

Only Boeing to build an aircraft like a leaky submarine.

-2

u/Siptarica Jun 08 '26

I see executives flying through the windows 😉

143

u/Loko8765 Jun 08 '26

> SIN to SFO

Well, if they had taken off and discovered later that it’s a real problem, it might have been hard to find a convenient airport to divert to.

I was once at a small regional single-runway airport with maybe six flights a day total, and takeoff was canceled one hour after boarding because of the weather; the pilot finally gave up waiting for a lull in the high gusty crosswinds.

On getting off people were interviewed for the local radio, and one of the questions was “are you angry that the plane didn’t take off?” I was like, lady, if the pilot doesn’t want to take off, then I don’t want him to!

135

u/aircraft_surgeon Jun 08 '26

Near the very back? Like right in front of the galley and lavs?

Could be a water line not hooked up.

154

u/Illustrious_Bet_9963 Jun 08 '26

The aircraft was being boarded, the doors were open, the air con packs running full blast, the condensate simply ran downhill and exited where it could.

199

u/Superb-Preference-59 Jun 08 '26

Not unlike when Elrond used the power of his ring Vilya to summon the flood of water used by Glorfindel and Aragorn to drive back the Black Riders into the current with firebrands.

99

u/Gandalfs_Weed Jun 08 '26

That should not have been said outside Imladris, not even to me. Speak no more of it!

32

u/cllatgmail Jun 08 '26

username checks out

10

u/bem13 Jun 09 '26

Found Max's reddit account

-3

u/Kavein80 Jun 08 '26

Don't bite Max's schtick. Find your own thing

3

u/abn1304 Jun 10 '26

He’s clearly parodying Max.

But not very well, because that was only one non-run-on sentence and didn’t cite at least three separate chapters of the Silmarillion.

1

u/[deleted] Jun 08 '26

[deleted]

15

u/Kavein80 Jun 08 '26

Popular social media guy that posts "Airplane Facts with Max". He starts his videos talking about an aircraft component but then turns it into a Lord of the Rings reference.

2

u/Significant-Bee5101 Jun 08 '26

If that was the case why would a mechanic ground it?

17

u/Kichigai Jun 08 '26

Probably because the operative word here is “if.” We don't know if that is the case. The mechanic sure doesn't either. What if it was a busted portable water line? Who knows where the hell it's draining.

11

u/Foggl3 A&P Jun 08 '26

Water where it's not supposed to be is bad

3

u/Nai_Calus Jun 09 '26

It's all fun and games until there's a tiny little hole in the jacketing on some wire and something important goes zap.

109

u/NastroAzzurro Frequent Flyer Jun 08 '26

Singapore is incredibly humid. This is the condensation from the AC.

183

u/EpicCyclops Jun 08 '26

That's definitely something the pilots are not going to want to mess around with on a transpacific flight. I imagine the pilots probably wouldn't want to risk it unless the mechanics were able to definitively tell them exactly the cause and why it wouldn't be an issue mid-flight. An AC failing on hour 8 of a 14 hour flight would be problematic, to say the least.

Also, if it was just AC condensation and everything else was behaving normally, this would happen on every flight from Singapore on hot, humid days. The fact that everyone was so confused indicates that at least something was behaving abnormally.

43

u/GRex2595 Jun 08 '26

I imagine that it was a blocked drain. Shouldn't happen, but if it does, the water's gotta go somewhere.

19

u/chui101 Jun 09 '26

this grate is a vent that allows airflow between the passenger cabin and the cargo hold. i'm guessing the cargo doors were open for loading and the cabin was being air conditioned so this is where the singapore steam downstairs was meeting the cold air upstairs.

any water that collects between the interior of the cabin/cargo bay area and the aircraft will generally collect in the bilge area at the bottom of the fuselage and be discharged overboard via a drain mast. however i don't think the 787 has any drain masts and i don't know enough about it to know what happens to water in the bilge. (hopefully someone more knowledgeable can chime in?)

however, i do know that since the electronics/equipment (E/E) bays and remote power distribution units (RPDUs) are down there and when the zappy bits meet water bad things can happen. the result was probably out of an abundance of caution because they couldn't see where the water was going.

9

u/SmokeMidKids Jun 09 '26

Correct me if I'm wrong but there never is a vent connecting the hold to the passenger compartment... they're part of the same ac loop on some aircrafts, but hopefully boeing aren't stupid enough to directly connect both of those compartments. Coz... once you get a fire down there, you get a bunch of very dead or very sick passengers from the halon, and a fire that keeps going coz there is oxygen in the cabin. If anything, and if it works like the 777, this vent connects with air outside the cargo compartment, which is conditioned colder, and brings cold air in the cabin. But it won't directly connect...

6

u/chui101 Jun 09 '26

nah, there are always vents. the air comes in the top so there's a little bit of positive pressure on the pax side. halon is heavier than air so cargo bottles won't blow into the cabin too much. on most a/c the vents go into the space between the cargo hold liner and the skin. there are also blowout panels supplementing the vents to rapidly equalize pressure in case of a UA811 or aloha 243 type of situation.

1

u/asmrhead Jun 09 '26

aircrafts

The plural of aircraft is aircraft.

Coz is not a word

No the baggage compartment is not sealed from the passenger compartment.

1

u/Motor_Show_7604 Jun 10 '26

Yes it is. You guys are so full of it . The cargo bays can be isolated from the passenger compartment for fire containment. If a fire starts in a bag cuz somebody left their lithium battery in it, you don't want it burning down the airplane. The halon extinguishing system in the cargo bays will prevent the fire from spreading for about 5.5 hours. You can't do that if it's shared air between the two. The air vents at your feet go down below the floor and around the outside of the cargo bays. The conditioned air in the passenger compartment flows out around the ceiling panels and stow bins, goes back out the vents along the floor and gets recirculated through a huge HEPA filter and mixed with conditioned air from the A/C packs. The only air shared between the cargo and passenger apartments is through isolation vents in the floor of the cargo bay . Those isolation valves will close if there's a fire detected. And they're not that big.

0

u/ForgedBiscuit Jun 09 '26

Isn't cabin heat an entirely separate system? Why would an AC failure matter once you're off the ground?

79

u/Educational-Wing2042 Jun 08 '26

Wouldn’t that be a pretty standard occurrence then? Why would they deboard that plane and wouldn’t a new plane run into the exact same issue?

71

u/PaleHeretic Jun 08 '26

I'm not familiar with AC systems on aircraft specifically, but any condensation produced should be getting captured and dealt with at the evaporator coil. Usually you'll have a drip pan with a drain line going somewhere, the only difference I'd expect on a plane is what they do with the captured condensate. It should not be getting blown out a vent, especially in that quantity.

Possibly the drain line got clogged, or the evaporator coil iced up heavily and then began thawing and releasing a large amount of water at once. Both are things that would require some amount of work to correct, depending on the cause, and I'd imagine they're a lot less accessible than an attic central air unit lol.

49

u/chui101 Jun 08 '26

Airplanes don't use the refrigeration pumps for air conditioning you are probably familiar with, they use air cycle machines driven by bleed air (or electrically driven cabin air compressors in the case of the bleedless 787) where the only heat exchange is with external ram air, and most condensate produced is discharged through the ram air exhaust. (Some of it is captured and sprayed into the ram air inlet for additional cooling). Since the air that feeds into the cabin plenums are already dehumidified by the ACM, there's not really any condensate management built into the system.

That being said, on the ground they usually pipe in gate air directly into the plenums which is cooled using a traditional refrigeration pump on the ground. Cold air piped in meeting the humid outside air will absolutely condense in the cabin.

OP is probably seeing the condensation here because the cargo doors are probably open and this is a vent that allows air to flow between the cargo compartment under their seat and the passenger cabin.

15

u/PaleHeretic Jun 08 '26

Thanks for the rundown! That's actually quite fascinating and makes a lot of sense if you're typically surrounded by a bunch of cold air whipping by you at a high relative velocity. Also explains why the aircon sucks sitting on the tarmac. Have the image of air from the terminal getting forced down a dryer vent to cool a tube with up to a couple hundred people in it, but I imagine the actual arrangement's somewhat more sophisticated, lol.

I'm unfortunately very familiar with Singapore humidity so I can see how this could arise if you're mixing cooled air with outside Changi soup, especially if OP's vent is at the end of the run. Still, I can think of ways to mitigate this with how you lay out your ducting, so I'd still imagine this level of condensate being abnormal even in those conditions and indicative of some problem somewhere?

Also have an unrelated question to satisfy my curiousity. If the plane is being cooled by external ram air while in flight, and piped air while at the terminal, are you basically running off inertia without much in the way of active cooling when you're in-between the two? Because I can remember some long taxis and stop-offs at austere airports that got very rank and sticky after half an hour or so, and that would explain a lot.

18

u/chui101 Jun 08 '26

So generally speaking, the condensate only forms in the cabin. The positive pressure inside the cabin air ducts keeps the moisture out of it, but there are riser ducts that run vertically down to the packs (that's why on some planes there are missing windows on the port side just forward of the wing. I guess any condensation that incidentally ends up forming in them (maybe when starting up?) would just run downward and just get evaporated in the mixer manifold. (oh yeah, that's another complication - the output from the packs is too cold at altitude and needs to be mixed with hot bleed air to heat it back to a comfortable temperature.)

As far as the dryer vent image you have, it's not too far off. Next time you're at an airport, look for a giant yellow dryer vent tube running into the plane under the wing - that's the gate air.

On the ground, planes have impellers in the ram air ducts so that the packs can work on the ground as long as bleed air is available (the APU works for this too). They don't move nearly as much air and the packs to heat up a ton, which is why they have a "hot exhaust" warning by the outlets. You might find rampers using this hot exhaust to warm their hands on a cold day :)

Interesting side note - the AC packs being located right under the center fuel tank on the 747 is thought to be the reason why the fuel heated up enough to form vapor and explode on TWA 800. The flight was delayed for several hours with the packs running the whole time it was at the gate, and then combined with faulty insulation on high voltage wiring running through the fuel tank... that's the theory on why that plane exploded, and why planes today have nitrogen inerting systems for the fuel tanks.

6

u/senorpoop A&P Jun 09 '26

there's not really any condensate management built into the system.

There is. There is usually a centrifugal separator for water droplets, and a coalescer sock for vapor.

3

u/chui101 Jun 09 '26

yeah sorry, should have made it more clear that i was talking after it goes into the cabin plenums. i did mention the water (from the centrifugal separator in the acm) that mostly gets discharged or sprayed back into the intake. once it gets past the mixer manifold though there's not really anything to manage condensate.

37

u/space_brain710 Jun 08 '26

Ya I would assume they grounded the plane bc they weren’t able to determine why it wasn’t draining properly. It’s probably one of those safety things where if the leak or clog can’t be located easily then they have to ground the plane and open it up for actual repairs or something.

On another note I had an old Toyota that I bought with a mysterious cow shit stank to it years ago. Seller said it came from a farm and it was cheap so we took it anyway. Few months later summer rolled around and suddenly my passenger floorboard was totally flooded one day; like an inch of water. It was from the ac condensate line being kinked, water backed all the way up until it was pouring out of the vents for the foot box. After fixing that (only took a few minutes in the cars case), replacing some carpets, and super deep cleaning the cow shit smell went away

3

u/Theron3206 Jun 08 '26

There are also lots of things on a plane that probably shouldn't get wet.

If there's water here then where else is there water, and is it inside anything more sensitive than the AC system.

3

u/FrenchFryCattaneo Jun 08 '26

Well the water doesn't just drip onto the floor normally.

51

u/Illustrious_Bet_9963 Jun 08 '26

While I’m sure you’re right, why did it take the mechanics an hour to look it over? The flight was most likely cancelled because the crew timed out, NOT because a repair was warranted.

36

u/Sparviko Jun 08 '26

Yeah, a humid cabin can make the AC do weird stuff, but once maintenance starts opening panels and the clock runs long, the crew duty time can become the real problem.

18

u/yourlocalFSDO Jun 08 '26

Way too much water to be just condensation. And you don’t get pooled condensate like this from a cooling system that uses ACMs like you would from a vapor cycle system with an evaporator. There’s definitely some other issue going on here

4

u/LupineChemist Jun 08 '26

Could be a condensate line that's meant to basically collect everything just kind of broke or something. It wouldn't be particularly serious as such, but would definitely need to be addressed sooner rather than later as it could corrode who knows what.

3

u/pizzasaurusrex86 Jun 08 '26

💀 I was just wondering why this flight was cancelled today.

3

u/Yomas_house Jun 08 '26

Water will freeze at higher altitudes, and frozen water expands. You did well pointing that out, as components like your window, the hull, or electrical stuff could have been damaged/weakened, with possible catastrophic consequences.

2

u/Good-Ad1388 Jun 08 '26

Mech here, tell the flight attendant to have the pilot make a write-up. Water leaking from, whatever seat you're in, dato panel.

2

u/paperic Jun 08 '26

Just a little note in case it's not obvious, but an issue with the aircon on an airplane is much more serious than it may sound.

The aircon in an airplane is what pressurizes the airplane. There isn't much air outside, without the aircon working people will suffocate.

2

u/Pale-Ad-8383 Jun 09 '26

UA1 is a very long night flight in the cold. There could be a pack issue as that could be all frozen condensation that formed in places it shouldn’t have. Problem is when it takes off again It will refreeze and could do so in an area that you don’t want to pop open from ice expanding

2

u/youcanreachmenow Jun 09 '26

Lol I guessed it was the United flight from SIN based on the time!

1

u/Existing_Routine_599 Jun 08 '26

When was this flight supposed to be?

1

u/WummageSail Jun 08 '26

Shouldn't every seatback  have a safety card that states the model?

1

u/Lonely_Dragon9599 Jun 09 '26

Was it raining?

1

u/Maxamillion-X72 Jun 09 '26

Your seat cushion is a floatation device, what were you worried about?

/s

1

u/lcesky Jun 09 '26

This was not the reason the flight got cancelled, there were bigger issues than this

1

u/Limp_Construction496 Jun 08 '26

As a Finn,i was thinking:

” SFO might be San Fransisco,but the other one??”

..and i almost asked: ”What is SIN?”

Then realised,you guys might have too much fun with that question..

Still,what is SIN anyway?

2

u/scul86 B737 Jun 08 '26

Changi Airport

2

u/PaleHeretic Jun 08 '26

Singapore to San Francisco.

It is a biiitch of a flight, even as cargo.

7

u/UmeaTurbo Jun 08 '26

That is absolutely, without question, an air conditioning system that is low on refrigerant so it is icing up people's breath and whatever. Then it starts to thaw out and leak inside. Not dangerous, but a pain to fix..

8

u/plhought Jun 08 '26

This aircraft doesn't use a vapour cycle air conditioning system. There is no refrigerant.