FlyHoss From United States of America, joined Feb 2005, 598 posts, RR: 0 Posted (6 years 4 months 3 weeks 2 days 11 hours ago) and read 6840 times:
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.
JetJeanes From United States of America, joined Oct 2004, 1415 posts, RR: 1 Reply 3, posted (6 years 4 months 3 weeks 2 days 11 hours ago) and read 6722 times:
o2,mask time i would imagine he was trying to get down as quicky as possible
Litz From United States of America, joined Dec 2003, 1745 posts, RR: 0 Reply 4, posted (6 years 4 months 3 weeks 2 days 10 hours ago) and read 6679 times:
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.
JetJeanes From United States of America, joined Oct 2004, 1415 posts, RR: 1 Reply 5, posted (6 years 4 months 3 weeks 2 days 10 hours ago) and read 6632 times:
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
IPFreely From United States of America, joined Dec 2006, 223 posts, RR: 0 Reply 6, posted (6 years 4 months 3 weeks 2 days 10 hours ago) and read 6595 times:
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 From United States of America, joined Feb 2005, 598 posts, RR: 0 Reply 7, posted (6 years 4 months 3 weeks 2 days 10 hours ago) and read 6585 times:
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)...
JetJeanes From United States of America, joined Oct 2004, 1415 posts, RR: 1 Reply 8, posted (6 years 4 months 3 weeks 2 days 10 hours ago) and read 6566 times:
It must not have been a rapid decompress but slow enough to wake the pilot.
777fan From United States of America, joined Jan 2006, 2402 posts, RR: 3 Reply 9, posted (6 years 4 months 3 weeks 2 days 8 hours ago) and read 6458 times:
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).
Dreamflight767 From United States of America, joined Dec 2008, 57 posts, RR: 0 Reply 10, posted (6 years 4 months 3 weeks 2 days 8 hours ago) and read 6422 times:
Se210 From United States of America, joined Feb 2005, 112 posts, RR: 1 Reply 11, posted (6 years 4 months 3 weeks 2 days 2 hours ago) and read 6259 times:
OPNLguy From , joined Dec 1969, posts, RR: Reply 12, posted (6 years 4 months 3 weeks 1 day 23 hours ago) and read 5494 times:
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.
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....
Access-Air From United States of America, joined Sep 2000, 1939 posts, RR: 15 Reply 13, posted (6 years 4 months 3 weeks 1 day 21 hours ago) and read 4804 times:
This could have turnmed into another Helios 737 problem if it had not been caught!!
OPNLguy From , joined Dec 1969, posts, RR: Reply 14, posted (6 years 4 months 3 weeks 1 day 21 hours ago) and read 4392 times:
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.
Se210 From United States of America, joined Feb 2005, 112 posts, RR: 1 Reply 15, posted (6 years 4 months 3 weeks 1 day 20 hours ago) and read 4325 times:
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.
OPNLguy From , joined Dec 1969, posts, RR: Reply 16, posted (6 years 4 months 3 weeks 1 day 20 hours ago) and read 4165 times:
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.
PSU.DTW.SCE From United States of America, joined Jan 2002, 6868 posts, RR: 29 Reply 18, posted (6 years 4 months 3 weeks 1 day 17 hours ago) and read 3074 times:
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 From , joined Dec 1969, posts, RR: Reply 19, posted (6 years 4 months 3 weeks 1 day 17 hours ago) and read 3001 times:
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.
Sponsor Message: 
From United States of America, joined Feb 2005, 598 posts, 
From China, joined Sep 2000, 534 posts, 
Printer friendly format 
