FlyHoss
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UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 1:19 pm

At about 19:05 CST tonight (Dec. 30), I heard (Minneapolis Center 119.52) UA 1112 declare an emergency for loss of pressurization and start a descent from FL370 to 10,000. A horn (cabin altitude warning horn, I believe) could be heard during the transmissions from UA 1112. The controller initially cleared the aircraft to FL210 or 240 and then to FL190; the UA crew correctly kept insisting on 10,000'. However, the problem was resolved relatively quickly and UA 1112 leveled at FL190. I believe they elected to continue to ORD. Any UA insiders know the nature of the pressurization loss?

We were traveling in the opposite direction and lost radio/voice reception (from the UA flight) in a few minutes, so I may have missed some details.
A little bit louder now, a lil bit louder now...
 
Tony Lu
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 1:35 pm

flightaware shows its a 735 from YYZ-ORD
 
tsaord
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 1:38 pm

What exactly happens during a Depressurization?

I have a flight Sunday morning I'm getting nervous already!
there are icons, then there are legends, then there is rick flair
 
jetjeanes
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 2:09 pm

o2,mask time i would imagine he was trying to get down as quicky as possible
i can see for 80 miles
 
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litz
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 2:24 pm

Quoting Tsaord (Reply 2):
What exactly happens during a Depressurization?

I have a flight Sunday morning I'm getting nervous already!

No need to get nervous, it's a very rare event.

Here's what happens ... normally the interior of the plane is pressurized to around 8,000 feet, irregardless of the outside altitude.

This is done by using bleed air from the engines to pump air into the cabin, and an outflow valve to regulate air bleed-off, maintaining the specified pressure. This allows fresh air to constantly circulate through the cabin.

When this system fails, several things happen all at once :

The oxygen masks the FA's talk about during the safetly briefing (which you DID listen to, right?) drop, and the passengers don the masks.

At the same time LOUD warning horns sound in the cockpit, the pilots realize what's going on, and they don their emergency oxygen masks and immediately proceed to decend down to 10,000 feet as fast as possible. At 10,000 feet, supplemental oxygen is no longer required.

The airplane is designed with sufficient oxygen to allow the airplane to safely descend from cruising altitude down to 10,000 feet.

This is something the airplane designers, the airlines, and the flight crews all know can happen, they've trained for it, and in the extrememly unlikely event that it should happen they are more than ready for it.

So, no worries !

- litz
 
jetjeanes
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 2:42 pm

And dont assume the mask fall in your lap... reach up and get it out of the panel door . there are 4 on each row on the inside on most a/c.. I guess if one is out of Order?? never did figure why 4 were in their in a 2 or 3 config..

What i dont understand is why he was only cleared to 19,000 in this event unless they got it semi repaired...

I remember the Ys-11s used to be presurized and when we got them as freight dogs they wernt. man when we would be around 10k or so and if you had a bad tooth whoa I left the jumpseat and literally laid in the galley floor in pain.on my back with my feet up in the pax seat.. thats got to be the worst pain I ever had..I drank most of the afternoon in Msy because i was scheduled back on the same plane that night.. I smuggle a liter of jack on board and consumed nearly the whole liter in a 2 hr period. and back on the floor...lol
i can see for 80 miles
 
IPFreely
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 2:53 pm

Quoting JetJeanes (Reply 5):
never did figure why 4 were in their in a 2 or 3 config..

I think there are 4 masks per 3 seats to accomodate passengers who have infants in their laps.
 
FlyHoss
Topic Author
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 2:57 pm

Quoting Tony Lu (Reply 1):
flightaware shows its a 735 from YYZ-ORD

Your post gave me an idea, to check the flight's status at United's web site. That site confirms UA 1112 originated in DEN for ORD, then continued to YYZ. I was quite sure I'd heard the flight number correctly.

Still, I'm curious as to what caused the pressurization loss in the first place, and how the situation was resolved (so relatively quickly)...
A little bit louder now, a lil bit louder now...
 
jetjeanes
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 3:04 pm

It must not have been a rapid decompress but slow enough to wake the pilot.
i can see for 80 miles
 
777fan
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 4:25 pm

Quoting JetJeanes (Reply 8):
but slow enough to wake the pilot.

Or put him/her to sleep. I'd almost rather have an explosive decompression because at least you'd know there was a leak as opposed to a slow one that lulls you into a coma (hopefully the sensor would avert that).

777fan
DC-8 61/63/71 DC-9-30/50 MD-80/82/83 DC-10-10/30 MD-11 717 721/2 732/3/4/5/G/8/9 741/2/4 752 762/3 777 A306/319/20/33 AT
 
Dreamflight767
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 4:54 pm

Quoting JetJeanes (Reply 5):
I guess if one is out of Order??

True true. But also if the F/As can't get to theirs fast enough they can grab one and in case there is a lap child.
 
se210
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RE: UA1112 DEN-ORD Depressurization

Sun Dec 31, 2006 10:54 pm

 
OPNLguy
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 1:56 am

Quoting Se210 (Reply 11):
See 08:05PM to 08:09PM in log:

I tend to think the 19,000 feet entries at 8:08, 8:09, 8:10, and 8:11 are not quite in context. You'll not that each is quickly followed by a 10,900 feet or 11,000 feet figure, and while I'm not aware of the programming specifics of flightaware, it would appear that 19,000 feet is the altitude that they were descending from, followed by their actual altitude.

18:18 39.87 -104.57 229 7100
18:19 39.87 -104.47 268 10000
18:19 39.87 -104.45 270 9700
18:20 39.85 -104.35 308 10300
18:21 39.83 -104.20 361 12600
18:22 39.85 -104.05 389 15200
18:23 39.87 -103.90 394 17600
18:24 39.88 -103.77 399 19500
18:25 39.90 -103.62 404 21400
18:26 39.90 -103.45 416 23200
18:27 39.92 -103.30 433 24700
18:28 39.93 -103.13 433 26300
18:29 39.93 -102.98 443 28000
18:30 39.95 -102.82 443 29900
18:31 39.97 -102.67 432 31200
18:32 39.97 -102.52 425 32700
18:33 39.98 -102.37 413 33600
18:34 39.98 -102.22 408 33000
18:35 40.02 -102.08 408 33000
18:36 40.03 -101.93 413 33000
18:37 40.05 -101.78 407 33000
18:38 40.07 -101.63 412 33000
18:39 40.10 -101.48 412 33000
18:40 40.12 -101.35 412 33000
18:41 40.13 -101.20 406 33000
18:42 40.15 -101.05 406 33000
18:43 40.17 -100.92 406 31000
18:44 40.18 -100.77 406 31300
18:45 40.20 -100.62 406 27600
18:46 40.22 -100.47 411 25000
18:47 40.22 -100.32 406 25000
18:48 40.22 -100.18 406 25000
18:49 40.22 -100.03 406 25000
18:50 40.22 -99.87 400 25000
18:51 40.22 -99.73 405 25000
18:52 40.22 -99.58 405 25000
18:53 40.22 -99.45 400 25000
18:54 40.22 -99.30 400 25000
18:55 40.22 -99.15 405 25000
18:56 40.22 -99.00 405 37000
18:57 40.22 -98.85 405 26300
18:58 40.22 -98.70 405 28300
18:59 40.22 -98.57 400 30200
19:00 40.22 -98.42 393 32000
19:01 40.22 -98.28 383 33000
19:02 40.22 -98.15 383 33900
19:03 40.22 -98.00 389 34500
19:04 40.22 -97.87 389 34800
19:05 40.22 -97.72 401 30800
19:06 40.22 -97.55 413 26400
19:07 40.22 -97.40 413 22700
19:08 40.22 -97.27 408 20400
19:09 40.22 -97.12 395 19000
19:10 40.20 -96.98 382 19000
19:11 40.20 -96.85 376 19000
19:13 40.20 -96.70 407 19000
19:14 40.20 -96.57 390 19000
19:15 40.20 -96.43 384 19000
19:16 40.20 -96.28 384 19000
19:17 40.20 -96.15 384 19000
19:18 40.20 -96.02 384 19000
19:19 40.20 -95.87 384 19000
19:20 40.20 -95.73 384 19000
19:21 40.20 -95.58 384 19000
19:22 40.20 -95.45 384 19000
19:23 40.20 -95.30 384 19000
19:24 40.20 -95.17 384 19000
19:25 40.20 -95.02 384 19000
19:26 40.20 -94.88 384 19000
19:27 40.18 -94.73 384 19000
19:28 40.22 -94.58 397 19000
19:29 40.25 -94.45 397 19000
19:30 40.28 -94.30 402 19000
19:31 40.32 -94.17 397 19000
19:32 40.35 -94.02 402 19000
19:33 40.38 -93.87 402 19000
19:33 40.38 -93.85 408 19000
19:34 40.40 -93.73 402 19000
19:34 40.40 -93.70 408 19000
19:34 40.42 -93.62 398 19000
19:35 40.43 -93.57 398 19000
19:36 40.48 -93.42 398 19000
19:37 40.52 -93.28 398 19000
19:38 40.55 -93.13 398 19000
19:39 40.58 -93.00 398 19000
19:40 40.62 -92.85 398 19000
19:41 40.65 -92.72 398 19000
19:42 40.68 -92.58 398 19000
19:43 40.72 -92.43 398 19000
19:44 40.75 -92.30 398 19000
19:45 40.78 -92.15 398 19000
19:46 40.82 -92.02 398 19000
19:47 40.85 -91.87 398 19000
19:48 40.88 -91.73 398 19000
19:49 40.92 -91.58 403 19000
19:50 40.95 -91.43 409 19000
19:51 40.98 -91.28 409 19000
19:52 41.02 -91.13 409 19000
19:53 41.05 -90.98 416 19000
19:54 41.08 -90.83 416 19000
19:55 41.12 -90.70 416 19000
19:56 41.15 -90.55 416 19000
19:57 41.18 -90.40 416 19000
19:58 41.22 -90.25 416 19000
19:59 41.25 -90.10 416 19000
20:00 41.28 -89.95 416 19000
20:01 41.32 -89.80 416 19000
20:02 41.35 -89.65 416 19000
20:03 41.38 -89.50 411 18100
20:04 41.42 -89.35 404 16900
20:05 41.43 -89.22 399 15400
20:06 41.47 -89.08 378 13600
20:07 41.48 -88.95 373 11800
20:08 41.52 -88.83 368 19000
20:08 41.53 -88.75 353 11000
20:09 41.55 -88.70 356 19000
20:09 41.57 -88.63 323 10900
20:10 41.58 -88.60 316 19000
20:10 41.62 -88.57 307 10900
20:11 41.65 -88.52 311 19000
20:11 41.65 -88.45 295 10100
20:12 41.67 -88.40 295 9400
20:12 41.67 -88.35 292 8400
20:13 41.68 -88.30 290 8100
20:13 41.68 -88.27 276 7600
20:14 41.70 -88.20 272 6900
20:14 41.72 -88.17 274 6000
20:15 41.75 -88.13 265 5900
20:15 41.77 -88.12 271 5800
20:16 41.80 -88.07 265 4800
20:16 41.83 -88.05 270 4200
20:17 41.87 -88.02 265 3100
20:17 41.88 -87.98 217 2500
20:18 41.92 -87.93 166 1600
20:19 41.95 -87.92 135 1000

What's also interesting is that the flight was at a normal 33,000 foot crusing altitude at 1842z, and then started down, leveling at 25,000 at 1846z. (For dispatch with an airconditioning pack (1 of 2) inop, 25,000 is the max altitude, and it's also the altitude one must descend to if a pack fails inflight should the remaining pack not be able to maintain the cabin). It looks like that they climbed back above 25,000, but later descended again, and kept it going until they leveled at 19,000.

Quoting FlyHoss (Reply 7):
Still, I'm curious as to what caused the pressurization loss in the first place, and how the situation was resolved (so relatively quickly)...

Probably a pressure controller or an outflow valve....
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
access-air
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 3:13 am

This could have turnmed into another Helios 737 problem if it had not been caught!!

Access-Air
Remember, Wherever you go, there you are!!!!
 
OPNLguy
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 4:03 am

Quoting Access-Air (Reply 13):
This could have turnmed into another Helios 737 problem if it had not been caught!!

Sorry, but that's an overly generalized statement, and an apples-to-oranges comparision. The United aircraft apparently pressurized normally, but later developed problems in maintaining the cabin, and the crew took appropriate actions. Helios, on the other hand, appears to never have pressurized in the climb after takeoff, and the hypoxia associated with their increasing altitude inhibited the crew's ability to diagnose and rectify the problem.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
se210
Posts: 62
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 4:11 am

OPNLGuy...

The listing I see from 08:05PM to 08:09PM in log: http://flightaware.com/live/flight/U.../20061231/0018Z/KDEN/KORD/tracklog
are listed in Eastern time (EST) when I view them. Looks like these match 19:05 to 19:09 in your listing (in Reply 12) which appears to be in CST. Anyway, basically shows a drop from 30,800 to 19,000 in 4 minutes.

Agree those 19,000 entries after 09:02PM in the log (20:02 on your listing) don't look accurate.

Regards. se210.
 
OPNLguy
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 4:33 am

Quoting Se210 (Reply 15):
Agree those 19,000 entries after 09:02PM in the log (20:02 on your listing) don't look accurate.

I mentioned this in another thread (can'trecall which), but various ASD-powered products like flightaware usually seem accurate when an aircraft is cruising, but transitions like climbing and descending often show some erratic results.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
VEEREF
Posts: 560
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 5:06 am

Quoting Tsaord (Reply 2):
What exactly happens during a Depressurization?

I have a flight Sunday morning I'm getting nervous already!

Also don't forget the involuntary flatulence and belch as the body depressurizes as well  Wink
Airplanes are cool. Aviation sucks.
 
PSU.DTW.SCE
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 7:38 am

Interesting.

I was on an AA flight from DEN-ORD that was about 30 minutes ahead of this particular flight yesterday.

Now we had no issues with cabin pressurization, but we were initially assigned at FL330. Due to the weather system over Nebraska & Iowa yesterday, there was moderate turbulence throughout the entire flight. The FA's were told to remain seated for the last hour of the flight. Over Iowa we dropped down to FL27 and climbed back up to FL330, and then made a few more altitude adjustments as the pilots were attempting to avoid the turbulence and fly above the cloud tops.

Perhaps this United flight was attempting to do some of the same - fly above the weather, avoid turbulence, all while dealing with this pressurization issue.
Due to the weather system, flying at 10,000 ft. may not have been a viable option - without knowing the specifics of this problem.
 
Vref5
Posts: 187
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RE: UA1112 DEN-ORD Depressurization

Mon Jan 01, 2007 7:48 am

Quoting PSU.DTW.SCE (Reply 18):
Perhaps this United flight was attempting to do some of the same - fly above the weather, avoid turbulence, all while dealing with this pressurization issue.

Doubtful. Turbulence is usually a comfort issue (assuming people are properly belted in, cabin crew not doing service, etc). Pressurization is a safety issue, first and foremost.

They would likely not be going to a higher altitude if they thought they had unresolved pressurization problems.

Absent pressurization problems or other serious safety issues, sure, changing altitude or heading is certainly common if warranted and feasible.

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