quote:

Originally posted by Top Gun Supply:

Yes, earlier in my life. I do still fly, but I don't get paid for it. And it is "rapid decompression". Much of your terminology and explanations are not right. I am sorry, but you either trained in Malaysia or you are not who you say you are.

We don't "compress" airplanes. We pressurize them.

Over three decades, over 80 aircraft, currently flying widebody, former 747 captain, many years of firefighting, corporate, fractional, charter, ambulance, and numerous other duties, yes, very much an aviator to this day, and still drawing a paycheck.

https://flightsafety.org/asw-a...id-depressurization/

It's depressurization.

You won't find "cabin decompression" checklists. You'll find them for loss of cabin pressurization, however. That's because it's a depressurization.

At altitude in a fire situation, we don't "decompress" a cabin." We depressurize it.

We don't have "differential compression" limits. We have differential pressure.

We don't lose cabin compression. No manufacturer refers to this. We lose cabin pressure.

While a decompression can occur, it's referred to, particularly in aircraft flight manuals, FCOMS, and other publications and checklists as a loss of pressure or depressurization, which it is.

The certification standards for transport category aircraft, 14 CFR 25, refer to the pressure vessel and pressurization, not compression:

https://www.ecfr.gov/cgi-bin/t...4.1.25_1365&rgn=div8

We don't compress airplanes. We pressurize them. Rapid loss of pressure is depressurization.

The use of "rapid decompression" or "explosive decompression" is often found in the movies and books and TV, and is incorrect. It's a rapid depressurization.

NTSB reported investigating a rapid depressurization...go figure...

http://avstop.com/april_2011/n...surization_event.htm

Both my terminology and explanation is exactly right.

quote:

Originally posted by sns3guppy:


There is no indication that a rapid depressurization occurred. There is no such thing as a "rapid decompression."

Have you ever had a rapid or explosive depressurization in an aircraft before? I have. Have you ever taken an altitude chamber ride before and experienced hypoxia in varying stages? I have.

TUC, or time of useful consciousness, is applicable to sudden exposure to a particular cabin pressure altitude, such as experienced in a rapid depressurization. It is not applicable here.

TUC is 15 seconds at FL410 and increase marginally with a descent in altitude, depending on the physiology of the individual.

I don’t recall TUC being that quick at FL410 but it isn’t very long, certainly less than a minute, which I believe is why one crew wears a mask at those altitudes.

I did the chamber ride at Edwards, the whole course.

We had to demonstrate loss of pressurization and recovery in initial check out and at the required annual school for Malibus and Mirages. You level off at FL250, set power etc., then pull the dump valve. If that isn’t rapid depressurization I don’t know what it could possibly be. It isn't rapid, it’s instant! Drop the gear, bank 45 degrees, and come down at ~6000 Fpm, without exceeding redline, or tearing the tail off, to 12,000’.

Thus far there is no indication of a rapid depressurization in the case in question.

A 737 is not a piper malibu.

One crewmember does not wear a mask at altitude unless the other leaves the flight deck. In practice, it's rare that the other crewmember puts on a mask anyway.

quote:

Originally posted by sns3guppy:


The use of "rapid decompression" or "explosive decompression" is often found in the movies and books and TV, and is incorrect. It's a rapid depressurization.

NTSB reported investigating a rapid depressurization...go figure...

http://avstop.com/april_2011/n...surization_event.htm

Both my terminology and explanation is exactly right.

You should probably let the FAA and NTSB know that they watch too many movies.

https://www.faa.gov/documentLi...Circular/AC25-20.pdf

https://www.ntsb.gov/Investiga...s/Pages/AAR9202.aspx

https://www.faa.gov/pilots/tra...dia/ac%2061-107a.pdf

quote:

Originally posted by cne32507:
A Delta MD-88 P&W engine lost it's fan blades on takeoff in 1996 at Pensacola. Blades sliced the cabin, penetrated the other side, killed two. I saw the plane later; it sat on the tarmac for weeks. Looked like a giant can opener was used. PNS 1996

Yep. I was remembering that. It was pretty bad. I was flying once a week for work back then. All along the eastern seaboard. Most were Delta MD-88 or United 727s. Kinda freaked me out where I would sit after that, especially when they would run up the engines.

Delta 1288

Quick donning masks are for the loss of pressurization. Not for the loss of cabin "compression."

If you ever worked as a pilot, apparently it's been a while. Have you read the regulation?

https://www.ecfr.gov/cgi-bin/t...4.2.91_1211&rgn=div8

quote:

Originally posted by sns3guppy:

quote:

Originally posted by SigSAC:
Normal rules dictate that speed be below 250 knots when below 10,000 feet. He didn't slow down to that speed until he was just below 5,000 feet.

How do you know that a speed reduction wasn't made until 5,000?

quote:

Originally posted by SigSAC:
Exemptions? ATC authorizes it, or an emergency dictates it. In this case, the latter is what would be the case.

What about this event required higher than 250 KIAS?

quote:

Originally posted by SigSAC:
He had plenty of altitude and speed to make the airport with one engine

It's a Part 25 aircraft; no extra altitude or speed is required. Fly normally. The aircraft flies on one or two engines without difficulty. The ability to fly is not in question, and additional altitude isn't necessary. Two engines are for performance, not simply to stay aloft.

quote:

Originally posted by SigSAC:
he most likely used speed and descent to expedite getting there without having to add power and yaw from the one remaining engine, and then dumped the rest of the speed once close.

Why would one expedite?

Yaw isn't an issue. That's what rudder trim is for. It's a turbojet airplane. It's flown wings level, trimmed, and normally.

No need to "dump speed." Slow on schedule, and as one would normally do. Stable approach, as always.

quote:

Originally posted by OKCGene:
I thought the engines cowl things have to have a Kevlar or something wrapping to contain pieces when this happens? I know the engines are creating enormous forces of energies when operating, but is it just not possible to contain these?

A typical turbine is operating 35,000-40,000 rpm. During a catastrophic failure, it's not uncommon to be uncontained. The parts get hot; exceptionally hot, which changes properties.

Earlier this year, an operator for whom I also work, had an uncontained failure on a turbine. I found engine pieces inside the cabin area, and have pictures of the window and fuselage where they penetrated. I helped remove the engine from the wing, and have pictures of the damage. It happens. Not often, but it happens.

I'll take them in order:

Speed reduction - it is based on the flight path that was represented in the initial Flightaware tracking (2nd post)

Speed - don't KNOW that they required that amount of speed - they just did keep it up until the lower altitude. My note that they appeared to keep speed up while dumping altitude is only my guess.

Engine and yaw - I know that yaw isn't as much a factor on turbojet aircraft. Again, based on the Flightaware track, they kept speed up even as they descended below 10,000 feet. I'm sure there will be questions, but the pilot is ultimately in command and should easily be able to justify all actions they took.

I agree about the part on what happens when the engine fails - at that speed, a puncture of the vessel is very likely.

quote:

Originally posted by sns3guppy:
Quick donning masks are for the loss of pressurization. Not for the loss of cabin "compression."

If you ever worked as a pilot, apparently it's been a while. Have you read the regulation?

https://www.ecfr.gov/cgi-bin/t...4.2.91_1211&rgn=div8

Yes, I know that. I have EROS masks.

The unplanned event is referred to as decompression and has always been. Apparently, depressurization can be used interchangeably. Compressed and pressurized mean he same thing. I started flying in 1989 and most of my time is in high altitude jets. Depressurize was referred to as a purposeful event. Decompression was referred to as an abnormal/emergency event. Tomato, tomato. For you to point that out as being incorrect is ridiculous.

If the armor around the tail engine of a DC10 couldn't prevent UA232 in Sioux City, then there's no way I'm willingly sitting in line with the compressor of a jet engine. Maybe it's statistically irrational, but there it is. It's one of my hangups, and this story just reinforces it.

quote:

Originally posted by sns3guppy:


Thus far there is no indication of a rapid depressurization in the case in question.

A 737 is not a piper malibu.

One crewmember does not wear a mask at altitude unless the other leaves the flight deck. In practice, it's rare that the other crewmember puts on a mask anyway.

Dude, I have noticed that every time we have some aviation-related thread you jump in and turn it into some sort of dick-measuring contest. You are not the only guy who flies jets on this forum. Chillax and don't get so wrapped around the axle on meaningless distinctions.

uncontained engine failure is something that's really, really rare. Like you can't see it on any chart. But even an event like this shouldn't happen as the FAA mandates containment for certification. So... where are we on the core root cause assessment. Let's see in a couple of years when they say.

quote:

Originally posted by RedneckRob:
And that's reason number two to wear a seatbelt.
Number one is air turbulence.

wearing a seatbelt may not have helped.

quote:

Originally posted by sigcrazy7:
If the armor around the tail engine of a DC10 couldn't prevent UA232 in Sioux City, then there's no way I'm willingly sitting in line with the compressor of a jet engine. Maybe it's statistically irrational, but there it is. It's one of my hangups, and this story just reinforces it.

I fly just about every week soemwhere in the world for work. I to can not sit inline with the compressor section of a turbofan engine. Gives me the creeps. I also spend a lot of time in the MRO organizations that service these engines and that does not help.

I love the aviation and shipping threads because they eventually always devolve into everyone arguing about experience and terminology.

Where’s that Michael Jackson eating popcorn meme?

quote:

Altitude / Time of Useful Consciousness
45,000 feet MSL / 9 to 15 seconds

Okay, I’ve seen this sort of chart before and puzzled over it, but I still have a question.
Even at the altitude where I live and despite being in my 70s, if I suddenly stop breathing, I can go 20 seconds or more without having to gasp for breath. When I can’t hold my breath any longer, I’m still far from losing unconsciousness. Plus, according to what I can find with a quick search, at 45,000 feet a breath would give me about 16% of the amount of oxygen I would get at sea level (and nearly 25% of what I get here), unlike the 0% that I get when I stop breathing. I would think, therefore, that that bit of oxygen would keep me going for even a little longer.

So my question is, What’s the basis for the 9 to 15 seconds of useful consciousness figure? Is there something about being at really high altitude that depletes our oxygen saturation faster than just not breathing at all? It’s not something I’ve noticed where I live, but I get 69% of sea level oxygen per breath rather than 16%, so I could be ignorant of something.

This explains it better than I could.

"The physiological effect of decompression depends upon the pressure differential, the duration of decompression and the final cabin altitude. The most severe hazards associated with a rapid decompression to high altitude is hypoxia. This hazard is particularly significant for the following three reasons.

a. In the case of high differential cabins with a cruising cabin altitude of 1,500 m – 2000 m (6000 to 8,000 ft), the crew is most unlikely to use oxygen equipment at the time of the decompression.

b. If the final cabin altitude is very high i.e. above 10,000 m (33,000 ft), the time of useful consciousness (TUC) for various crew members breathing air may be reduced by as much as one third from the figures which would normally be expected for that ambient altitude. This is due to the fact that during the escape of gas from the lungs, the partial pressure of oxygen in the alveoli is reduced to below 40 mm Hg which is the approximate value for the oxygen tension in the venous blood. There is an actual reversal of the oxygen diffusion gradient across the alveolar membranes and oxygen passes back into the lungs from the venous blood. Immediately following a rapid decompression to these very high altitudes, therefore, the arterial blood leaving the heart would be carrying a little or no oxygen and the onset of hypoxia would be very rapid. This shows the advantage of having the pilot or one of the pilots on oxygen the whole time when ambient aircraft altitude exceeds 8.5 Km (30,000 feet).

c. The final altitude after decompression may be above 12,000 m (40,000 ft) and positive pressure breathing would be required to prevent hypoxia."

quote:

Originally posted by RAMIUS:
I love the aviation and shipping threads because they eventually always devolve into everyone arguing about experience and terminology.

Where’s that Michael Jackson eating popcorn meme?

Well, there was this thing about the airplane bringing his shipment of popcorn...

quote:

Originally posted by sigfreund:

quote:

Altitude / Time of Useful Consciousness
45,000 feet MSL / 9 to 15 seconds

Okay, I’ve seen this sort of chart before and puzzled over it, but I still have a question.
Even at the altitude where I live and despite being in my 70s, if I suddenly stop breathing, I can go 20 seconds or more without having to gasp for breath. When I can’t hold my breath any longer, I’m still far from losing unconsciousness. Plus, according to what I can find with a quick search, at 45,000 feet a breath would give me about 16% of the amount of oxygen I would get at sea level (and nearly 25% of what I get here), unlike the 0% that I get when I stop breathing. I would think, therefore, that that bit of oxygen would keep me going for even a little longer.

So my question is, What’s the basis for the 9 to 15 seconds of useful consciousness figure? Is there something about being at really high altitude that depletes our oxygen saturation faster than just not breathing at all? It’s not something I’ve noticed where I live, but I get 69% of sea level oxygen per breath rather than 16%, so I could be ignorant of something.

It’s not that you stop breathing. You keep on breathing but there isn't enough oxygen to keep you going. I’m the most experienced victim on this Forum at this, after 7 years since being diagnosed with pulmonary fibrosis. Now even at less than 1000’ above sea level, I must have supplemental oxygen to do much moving around, almost constantly. I would pass out at a few thousand feet without supplemental O2. Your lungs take the oxygen and get it into your blood stream to power your muscles and systems, as I understand it.

Time of useful consciousness means “the amount of time an individual is able to perform flying duties efficiently in an environment of inadequate oxygen supply.”

When I did the high altitude chamber course at Edwards AFB, after most of the day of lectures, etc., we were put in this chamber, seated, given O2 masks, and slates with a number of simple problems to work out. The technicians ran us to various altitudes and finally to 25,000’ where we were to remove our masks and work on the problems on the slate. When we felt we were losing concentration, hopefully before losing consciousness, we were to put the masks back on and breathe normally. At between 4 to 5 minutes, some started replacing their masks. I made it a bit further but somewhere around 6 minutes or so, I went back to the mask. The fellow at seat no. 7 kept on, concentrating on his slate. The corpsman called out, “No. 7, how are you doing?” No response. “Hey, No.7, put your mask on.” No response, he kept head down working away. “Hey, No. 7, put your mask on, you’re going to die!” Finally the corpsman went over and put the mask on. No. 7’s lights were on but nobody was home!

TUC gets a lot shorter at higher altitudes.

Side drift: What about what happened in the Payne Stewart death? Flying along at altitude, something happened, it crashed. A military plane caught up with it, the pilot observed frosted over windows and no movement in the plane. Apparently some sort of pressurization failure and death from freezing to death or no oxygen. Two highly trained pilots but apparently it happened so quickly that nothing was done successfully. The plane continued to fly in a normally operational status until it finally ran out of fuel.

So, what happened? I've never learned of a good explanation, maybe no one was able to fully and satisfactorily state what went wrong so quickly and incapacitated everyone.

This is a mystery to me.

quote:

Originally posted by RAMIUS:
I love the aviation and shipping threads because they eventually always devolve into everyone arguing about experience and terminology.

Where’s that Michael Jackson eating popcorn meme?

LOL! For what's it's worth, I've been face-to-face, shot with, and broke bread with Furlough on more than one occasion. I cannot attest for his direct pilot knowledge, but I will say that he is the kind of man I hope is flying the plane I'm in.

Almost forgot....