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vpat48
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Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 4:21 am

This is fairly new story and i only see it's just coming across the news sources. A 9W flight from Mumbai to Jaipur had to turn back after the crew forgot to select a switch that helps maintain cabin air pressure during take-off.

NEW DELHI: A Jet Airways flight with 166 passengers from Mumbai to Jaipur had to turn back shortly after take-off this morning, allegedly over a bizarre mistake by the crew.
Over 30 passengers have suffered ear and nose-bleed after the crew on flight 9W 697 reportedly forgot to select a switch that helps maintain cabin air pressure during take-off.

Oxygen masks were deployed. Many passengers have complained of headache.

All the affected passengers are being attended to by doctors at the airport.



Sources:
https://www.ndtv.com/india-news/jet-air ... lo-1919261

https://twitter.com/CNNnews18/status/10 ... 6579621888
 
Sand0rf
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 5:59 am

I believe this can only happen when the pressurization mode switch is set to Manual and the outflow valve is completely opened. But this would trigger a cabin altitude warning when climbing over 10000 feet... Strange story
 
sibibom
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 6:12 am

Wait there is a button that controls every's life? And if a crew forgets, its game over for all?
 
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bgm
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 6:15 am

sibibom wrote:
Wait there is a button that controls every's life? And if a crew forgets, its game over for all?


Yep. Another excellent design feature of the 737.

https://en.wikipedia.org/wiki/Helios_Airways_Flight_522
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neomax
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 6:22 am

Why does such a switch even exist in the first place? I assume this would only be used when descending below a certain altitude instead of ascending above it.
 
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SomebodyInTLS
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 10:53 am

Obviously this was a big boo-boo... but some of the passenger reactions - "no staff to help...no announcement on board to wear the oxygen mask" - seriously?!? I could have sworn I remember being told something about putting on an oxygen mask... like when it appears or something... EVERY SINGLE TIME BEFORE AN AIRCRAFT TAKES OFF!
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KLDC10
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 11:00 am

SomebodyInTLS wrote:
Obviously this was a big boo-boo... but some of the passenger reactions - "no staff to help...no announcement on board to wear the oxygen mask" - seriously?!? I could have sworn I remember being told something about putting on an oxygen mask... like when it appears or something... EVERY SINGLE TIME BEFORE AN AIRCRAFT TAKES OFF!


Indeed. They're not just for decoration - if you see one hanging there, put the damn thing on!

That said, there's also a checklist pilots are supposed to go through every single time before an aircraft takes off - it seems like no one was paying attention that day ;)
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caoimhin
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 1:01 pm

neomax wrote:
Why does such a switch even exist in the first place? I assume this would only be used when descending below a certain altitude instead of ascending above it.


Is it a maintenance mode/function?
 
zuckie13
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 1:33 pm

Could they have done a packs off takeoff and then never turned them back on (or even never turned them on after engine start)? I think that is just as likely as the outflow valve.
 
intrepidflyer
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 2:03 pm

Surely some automation could exist here. Is this a classic 737..
 
zuckie13
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 2:52 pm

intrepidflyer wrote:
Surely some automation could exist here. Is this a classic 737..


Well, if you set it correctly, the pressurization itself is managed automatically.

But....
1) If you leave it to manual (which is there for testing and in case the automation fails for some reason) it won't work (This was what happened on the Helios flight)
2) If you don't turn on the source of pressurized air (the packs) which you do have to turn off for a bit to start the engines it won't work.

Maybe some planes turn the packs off an on automatically? The 737 certainly does not.
 
LupineChemist
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 4:11 pm

neomax wrote:
Why does such a switch even exist in the first place? I assume this would only be used when descending below a certain altitude instead of ascending above it.


Would this have anything to do with pressurization for high altitude airports?
 
cbphoto
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 5:34 pm

I can't speak for the 737, as I don't fly that equipment. However, on the MD-80 series aircraft, there is an automatic and a manual way of controlling the cabin pressurization. During normal, routine operations, the pressurization system is controlled automatically, with little inputs from the flight crew. However, should the system fail (both primary and back up) on the automatic pressurization controller, the flight crew can control the cabin pressurization manually, to continue normal flight operations. You would not want the pressurization system to fail in flight and dump the cabin (as that would be a rapid decompression situation, and you would have to be able to descend the cabin on landing, as you would not want to land with the airplane still fully pressurized. So the manual system is a backup to the backup for the airplane. It is also possible that the automated cabin pressurization system can be placed on MEL, requiring the crew to manually control the system throughout all phases of the flight. It will be interesting to see how the crew ignored or didn't realize the signs of the aircraft not being pressurized. I can tell you from experience, upon rotation your ears will pop like crazy during a normal, un-pressurized climb in commercial jet. Also, the flight deck area will be significantly nosier as the non of the window seals would be sealed from the pressurization.
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spacecadet
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 5:36 pm

sibibom wrote:
Wait there is a button that controls every's life? And if a crew forgets, its game over for all?


The cockpit is literally filled with switches and knobs that could kill you if they're set incorrectly and warnings are ignored and/or don't work. That's why pilots go through years of training, have years of experience before they're allowed in a commercial cockpit and have checklists to make sure they set everything correctly.

Cabin pressure is a checklist item: http://www.b737.org.uk/nnp.htm

Scroll down, it's "pressurization mode selector" set to AUTO.

There is a warning horn if the cabin altitude rises above a certain number (though I'm not sure what that altitude actually is).

We don't know the full story here, and may never because it's not a story the media's likely to stay on top of. But at this point it's just as likely that some mechanical problem developed and the pilots *did* react to it, descending the plane once they received the cabin altitude warning, as it is that they "forgot" to set the selector correctly. Nobody died here and the pilots remained in control, unlike, say, the Helios accident. That suggests to me that the plane (or at least the cabin altitude) never got high enough to cause hypoxia.
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Antarius
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 5:48 pm

neomax wrote:
Why does such a switch even exist in the first place? I assume this would only be used when descending below a certain altitude instead of ascending above it.


Maintenance as well as unpressurized ferry flights (maintenance re positioning in case there is an issue/broken window etc).
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Antarius
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 5:51 pm

spacecadet wrote:
There is a warning horn if the cabin altitude rises above a certain number (though I'm not sure what that altitude actually is).

We don't know the full story here, and may never because it's not a story the media's likely to stay on top of. But at this point it's just as likely that some mechanical problem developed and the pilots *did* react to it, descending the plane once they received the cabin altitude warning, as it is that they "forgot" to set the selector correctly. Nobody died here and the pilots remained in control, unlike, say, the Helios accident. That suggests to me that the plane (or at least the cabin altitude) never got high enough to cause hypoxia.


I believe it is 10,000 feet.

I think there is more to the story. Even if they forgot to set the switch to AUTO, the warning horn should sound allowing them to pressurize without the masks dropping.
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kabq737
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 6:05 pm

bgm wrote:
sibibom wrote:
Wait there is a button that controls every's life? And if a crew forgets, its game over for all?


Yep. Another excellent design feature of the 737.

https://en.wikipedia.org/wiki/Helios_Airways_Flight_522

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bennett123
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 6:37 pm

My recollection from the Helios crash is there is a horn.

Problem is that the same horn for de pressurisation also sounds if undercarriage is not raised.
 
stratclub
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 6:54 pm

Maintenance and the flight crew missed it. When maintenance preflights an aircraft, switches circuit breakers and and controls are suppose to be set to specific position and then the flight crew didn't run their checklist correctly either. There is no such thing as an accident, just an accumulation of errors that turn out deadly.
 
DSFTEBMNZ
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 7:19 pm

There is something wrong with this news story. The plane ascended to 11,000 feet before turning back, according to several articles. Masks deploy at 14,000 feet. I have flown unpressurised aircraft to 12,000 feet many times without bleeding all over the place.

The US FAA requires that "... At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) ... the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration". In other words, for up to 30 minutes, flight up to 14,000 feet is not considered life threatening or even debilitating , even for the flight crew.

I don't know how to include the link to FlightRadar24 app here, but if you have access, play back the first September 20 flight (there are two including the replacement flight) of the 737 VT-JGS performing flight 9W697. It levels off at 11,000 feet. If the oxygen masks deployed, there's something else going on.

Look for more details on this news to make it believable.
Last edited by DSFTEBMNZ on Thu Sep 20, 2018 7:36 pm, edited 1 time in total.
 
m007j
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 7:34 pm

bennett123 wrote:
My recollection from the Helios crash is there is a horn.

Problem is that the same horn for de pressurisation also sounds if undercarriage is not raised.


The horn is tonally the same, however I believe the gear configuration horn is a constant tone while the pressurization alarm is a repeating set of short tones. You can hear the alarm in the background of the SWA1380 incident if you look up the ATC video on YouTube
 
aca36
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 7:34 pm

neomax wrote:
Why does such a switch even exist in the first place? I assume this would only be used when descending below a certain altitude instead of ascending above it.


Cuz it's a boeing :lol:
 
spacecadet
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 7:40 pm

Nose and ear bleeds would be most likely to happen with a sudden change in pressurization, which matches what some of the passengers said they felt. So either rapid decompression or the opposite, but "rapid compression" doesn't seem possible in an airplane to the extent that it would cause bleeding. But I don't know how fast the system actually works if the pilots switched it on at, say, 11,000 feet (the supposed maximum altitude they reached). I just can't imagine it works that fast, so it seems to me that rapid decompression is more likely.

Nose and ear bleeds are not a symptom of a gradual climb to 11,000 feet in an unpressurized plane. So there's definitely a piece missing to this story. Either the pilots switched the system on at altitude and it worked fast enough to cause those bleeds, or, I think more likely that the system was actually on and the plane rapidly depressurized for some reason.
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Gonzalo
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Thu Sep 20, 2018 7:43 pm

bgm wrote:
sibibom wrote:
Wait there is a button that controls every's life? And if a crew forgets, its game over for all?


Yep. Another excellent design feature of the 737.

https://en.wikipedia.org/wiki/Helios_Airways_Flight_522


Your comment sounds ignorant plain and simple.
I hope you’re trying to be ironic or something like that.
Otherwise, you have not a clue about aviation, statistics, and what is the true meaning of a successful design, since the 737 is probably the most evident case of a brillant design evolving through decades and still having future improvements and developments to come.
Regarding the “switch that can kill everyone”, there are dozens of those in every aircraft flying around, no matter if it is a Boeing, Airbus, Embraer, CRJ, Antonov or whatever.

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intrepidflyer
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Fri Sep 21, 2018 12:01 am

I have a question - if this affected the pax so much - surely the pilots would have been just as impacted?
 
ewt340
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Fri Sep 21, 2018 12:12 am

Damn, this is f*ck up.
 
Newbiepilot
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Fri Sep 21, 2018 1:42 am

neomax wrote:
Why does such a switch even exist in the first place? I assume this would only be used when descending below a certain altitude instead of ascending above it.


Every airplane can turn off air conditioning packs if there is a problem. There is also a manual override and ability to increase cabin altitude, which is necessary when landing at high altitude airports. The pilots are supposed to know how to operate the airplane and follow checklists
 
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TheRedBaron
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Fri Sep 21, 2018 2:04 am

If the Aircraft never went above 11 000 feet there is some missing information, either the PAX were not affected as much, or the cabin depressurized rater quickly giving the PAX a headache due low oxygen and ear and nose pain due to decompression.

On the PAX that did not use the mask, that is simply amazing... maybe they think oxygen masks are for cats to play with ! LOL

Hope the info on the incident comes out...

Best Regards

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FlyingSicilian
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Re: Jet Airways flight turns back to BOM after cabin pressure loss causes nosebleeds

Fri Sep 21, 2018 2:09 am

Doesn't the feature also exist to vent smoke from the cabin or am I thinking of the later 707s and 727s?
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