Author Topic: Not a good month to fly  (Read 4501 times)

Hawkmoon

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Not a good month to fly
« on: July 14, 2018, 02:59:31 PM »
A day or two ago a commercial airliner in China depressurized and descended 25,000 feet in ten minutes ... because the co-pilot was vaping in the cockpit and accidentally shut down the cabin pressurization system in an effort to conceal the smoke.

Not to be outdone, Ryanair had a plane drop 30,000 feet in five minutes.

https://www.dailystar.co.uk/news/world-news/716352/Ryanair-flight-emergency-landing-FR7312-Dublin-Frankfurt-Germany-Zadar-Croatia

Ouch!
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Fly320s

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Re: Not a good month to fly
« Reply #1 on: July 14, 2018, 04:08:36 PM »
OH MY GOD!!!  Run for the hills and ban airplanes on the way!

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Hawkmoon

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Re: Not a good month to fly
« Reply #2 on: July 14, 2018, 04:45:22 PM »
Is there any industry (or regulatory) standard for emergency descents? I thought the article I read on the Chinese incident said that a descent of 25,000 feet in ten minutes was the standard for an emergency descent following cabin depressurization. The Ryanair flight descended more than twice as fast as the Chinese aircraft.

How long is the emergency oxygen supply good for, anyway? And how low does the plane have to get? IIRC, modern aircraft are pressurized to something like 12,000 or 14,000 feet. I know I've been at the summit of Pike's Peak, which is a bit over 14,000 feet, and I didn't need oxygen. I wasn't going to be running any marathons at that altitude, but I wasn't suffering hypoxia, either.
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KD5NRH

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Re: Not a good month to fly
« Reply #3 on: July 14, 2018, 05:46:51 PM »
Is there any industry (or regulatory) standard for emergency descents?

Well, nature generally recommends no more than 32ft/s/s.  For 30,000 feet, that's somewhere in the neighborhood of 40 seconds.  6,000 feet per minute is nowhere near the power dive that the media seems to be trying to play it up as.  After all, have you ever seen a skydiver crushed by the pressure changes during their free fall?

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How long is the emergency oxygen supply good for, anyway?

Up to 20 minutes, depending on the brand/model oxygen generators used.  I suspect most are a bit over half that.  Hence the usual target of getting to 10k or below in 10 minutes or less.

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And how low does the plane have to get?

AFAICT, 14k feet is the usual trigger point for releasing the masks.

Fly320s

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Re: Not a good month to fly
« Reply #4 on: July 14, 2018, 08:09:11 PM »
Is there any industry (or regulatory) standard for emergency descents?

10 minutes to 10,000 is the only one I know of.  And that is mainly for the oxygen requirement for the crew, not the passengers.

Oxygen generators are 12 to 20 minutes of use and most planes will auto-deploy the masks at 14,000 feet cabin altitude, like KD5 said.  We can manually release the masks at any altitude from the cockpit and the flight attendants have a tool to pop the mask doors if needed.  FYI, the O2 doesn't start flowing until you pull down on the mask, pulling the pin in the process.
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RoadKingLarry

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Re: Not a good month to fly
« Reply #5 on: July 14, 2018, 08:34:48 PM »
What is the O2 generator set up?
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Hawkmoon

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Re: Not a good month to fly
« Reply #6 on: July 14, 2018, 08:43:34 PM »
The article I read about the Chinese incident commented on (and seemed to take issue with) the fact that after the descent, the flight crew just took it back up to altitude and continued the flight. Which means that for the rest of the trip the passengers (and crew, I suppose) were all at risk because if there had been an accidental decompression due to causes other than the co-pilot being a doofus, there wouldn't have been any oxygen available.
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230RN

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Re: Not a good month to fly
« Reply #7 on: July 14, 2018, 10:13:35 PM »
What is the O2 generator set up?




Interesting chemistry there in the "Chemical oxygen generator."  The percussion cap starts the burning of Potassium Superoxide (KO2) in the canister which generates O2.

KO2 looks funny from a valence point of view but sort of makes sense from a complex structural point of view.  Kind of. Meaning I can't figure it out from my 1950 AD chemistry.

Didn't want to delve into it too deeply.  Just wanted a visual sense of what the generator in the planes looked like.

Terry

Pic in public domain
« Last Edit: July 15, 2018, 09:23:52 AM by 230RN »

just Warren

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Re: Not a good month to fly
« Reply #8 on: July 14, 2018, 10:48:19 PM »
Quote
Well, nature generally recommends no more than 32ft/s/s.  For 30,000 feet, that's somewhere in the neighborhood of 40 seconds.

I'm soooooo tired of the Patriarchy mansplaining their physics privilege.
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Fly320s

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Re: Not a good month to fly
« Reply #9 on: July 15, 2018, 08:00:45 AM »
I'm soooooo tired of the Patriarchy mansplaining their physics privilege.

Especially when he doesn't factor in terminal velocity.
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230RN

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Re: Not a good month to fly
« Reply #10 on: July 15, 2018, 09:25:23 AM »
I'm soooooo tired of the Patriarchy mansplaining their physics privilege.

:rofl:

Awwww, poor baby.   >:D

Especially when he doesn't factor in terminal velocity.

Seven miles per second.  "For a spherical chicken in a vacuum."

(But of course, sphericity doesn't matter in a vacuum.)

REF:
Hatcher's Notebook pp 517, 553 and surrounding.
Extracted quote from page 552:
"In high school physics we were taught that..."


« Last Edit: July 15, 2018, 10:15:20 AM by 230RN »

Hawkmoon

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Re: Not a good month to fly
« Reply #11 on: July 15, 2018, 10:40:12 AM »
Well, nature generally recommends no more than 32ft/s/s.  For 30,000 feet, that's somewhere in the neighborhood of 40 seconds.

More like 30 seconds ...
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Fly320s

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Re: Not a good month to fly
« Reply #12 on: July 15, 2018, 11:06:57 AM »
More like 30 seconds ...

In a vacuum.
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RoadKingLarry

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Re: Not a good month to fly
« Reply #13 on: July 15, 2018, 11:32:33 AM »


Interesting chemistry there in the "Chemical oxygen generator."  The percussion cap starts the burning of Potassium Superoxide (KO2) in the canister which generates O2.

KO2 looks funny from a valence point of view but sort of makes sense from a complex structural point of view.  Kind of. Meaning I can't figure it out from my 1950 AD chemistry.

Didn't want to delve into it too deeply.  Just wanted a visual sense of what the generator in the planes looked like.

Terry

Pic in public domain

Nothing new under the sun.
These were always fun to use.
https://en.wikipedia.org/wiki/Oxygen_Breathing_Apparatushttps://en.wikipedia.org/wiki/Oxygen_Breathing_Apparatus

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Though it looks bulky and unwieldy it is a light and comfortable device to wear and does not much interfere with the user's freedom of movement
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Re: Not a good month to fly
« Reply #14 on: July 15, 2018, 04:31:25 PM »
:rofl:

Awwww, poor baby.   >:D

Seven miles per second.  "For a spherical chicken in a vacuum."

(But of course, sphericity doesn't matter in a vacuum.)

REF:
Hatcher's Notebook pp 517, 553 and surrounding.
Extracted quote from page 552:
"In high school physics we were taught that..."

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230RN

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Re: Not a good month to fly
« Reply #15 on: July 15, 2018, 04:55:46 PM »
....
« Last Edit: July 16, 2018, 06:50:18 AM by 230RN »

KD5NRH

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Re: Not a good month to fly
« Reply #16 on: July 15, 2018, 06:56:44 PM »
We can manually release the masks at any altitude from the cockpit and the flight attendants have a tool to pop the mask doors if needed.

The part I'm curious about is how much it costs to replace them all if you have an in flight deployment.  I know they're not particularly cheap as one-off purchases, but I'd assume airlines get serious bulk discounts.  Plus presumably (if it's otherwise airworthy) the plane can still be flown empty to the maintenance facility of choice with the pilots carrying portable oxygen (or just replacing the pilots' bottle(s)) for that flight.

Have they given you a "this costs $x if you do it unnecessarily, but not doing it when it is needed costs lives" talk about that particular system?

Fly320s

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Re: Not a good month to fly
« Reply #17 on: July 15, 2018, 09:30:00 PM »
I don’t know the costs.  Since it is airplane related, I assume $$$!!!

FWIW, unused masks can be stuffed back in and closed up.
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Hawkmoon

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Re: Not a good month to fly
« Reply #18 on: July 15, 2018, 10:22:13 PM »
I don’t know the costs.  Since it is airplane related, I assume $$$!!!

FWIW, unused masks can be stuffed back in and closed up.

Sort of.

If I understand it, each "package" includes a group of two, three, or four masks, depending on how many seats in that bank. The masks are all fed from a common canister, and pulling the lanyard from any one of the masks fires up the generator and starts oxygen flowing to however many masks are in that group. So if I understand it correctly, you can only stuff the masks up and close the hatch if none of the masks in that group were activated.

And the way the airlines are cramming people into planes these days, the possibility of finding two, three, or four unused seats all together is between slim and none. (And Slim left town.)
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Fly320s

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Re: Not a good month to fly
« Reply #19 on: July 15, 2018, 10:37:49 PM »
You are probably right.  I don’t know enough about the system to contradict you.  I was mainly refering to an accidental deployment.  Or a test deployment, which must happen every so often.
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BobR

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Re: Not a good month to fly
« Reply #20 on: July 16, 2018, 10:13:37 AM »
Sort of.

If I understand it, each "package" includes a group of two, three, or four masks, depending on how many seats in that bank. The masks are all fed from a common canister, and pulling the lanyard from any one of the masks fires up the generator and starts oxygen flowing to however many masks are in that group. So if I understand it correctly, you can only stuff the masks up and close the hatch if none of the masks in that group were activated.

And the way the airlines are cramming people into planes these days, the possibility of finding two, three, or four unused seats all together is between slim and none. (And Slim left town.)

The "give a sharp pull" is a very important part of making these things work so it is a possibility that there could be a group of several that don't understand because they didn't listen to the safety brief given by the passenger waitress as they were preparing to roll back from the dock. I mean, have you ever looked around during the safety brief, nobody and I mean nobody listens. I guess if you made a safety brief app it would work a little better. ;)

bob

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Re: Not a good month to fly
« Reply #21 on: July 16, 2018, 10:27:48 AM »
I mean, have you ever looked around during the safety brief, nobody and I mean nobody listens. I guess if you made a safety brief app it would work a little better. ;)

bob

I'm not sure if they were doing the aviation water survival training via the ASTC schools when you were in, but I can tell you, after I did that initial training at Lemoore, every time since that I have flown commercial, the first thing I do after I sit down is a 360 for exits and non-visibility reference points.  :laugh:
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MillCreek

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Re: Not a good month to fly
« Reply #22 on: July 16, 2018, 10:38:36 AM »
I'm not sure if they were doing the aviation water survival training via the ASTC schools when you were in, but I can tell you, after I did that initial training at Lemoore, every time since that I have flown commercial, the first thing I do after I sit down is a 360 for exits and non-visibility reference points.  :laugh:

When I am in my seat, I count the number of seatbacks to the nearest fore and aft exit points.  I figure that will make it easier when I am choking on smoke after the crash.
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Ben

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Re: Not a good month to fly
« Reply #23 on: July 16, 2018, 10:50:31 AM »
When I am in my seat, I count the number of seatbacks to the nearest fore and aft exit points.  I figure that will make it easier when I am choking on smoke after the crash.


Or else just:

https://youtu.be/4TuEWtXBT_0
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BobR

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Re: Not a good month to fly
« Reply #24 on: July 16, 2018, 11:27:08 AM »
I'm not sure if they were doing the aviation water survival training via the ASTC schools when you were in, but I can tell you, after I did that initial training at Lemoore, every time since that I have flown commercial, the first thing I do after I sit down is a 360 for exits and non-visibility reference points.  :laugh:

I did the full meal deal every four years whether I want to or not, the altitude chamber, other physiology stuff, water survival including the single dunker and helo dunker, The highlight of every trip was getting thrown into the ocean off of North Island in strings of 7 or 8 and bobbing around while waiting for the helo to come get you.

I have flown exactly two times since I retired from active duty, first because I had nowhere to go and then after 9-11 just because. I did have to get on a plane to get to Hawaii and back. I sure will be glad when they get that bridge built. ;)

bob