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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 24th Mar 2014, 00:02
  #7601 (permalink)  
 
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Slow-setting hypoxia

Thanks to FE Hoppy, I just dug up the following references:

Volume of air entering the cabin from the cargo hold

From which I gather that there is air entering the cabin from the cargo hold, in particular CO2 (Carbon dioxide, not monoxide), from, for example, dry ice, under even normal circumstances. It remains to be calculated just how much dry ice would be needed to attain a lethal level of 3%.

The second point would be, what if it's not just a small escape of this gas, but a large one which may have been triggered by (a) a smouldering fire damaging the dry ice containers, and (b) what would be the effect of extremely cold CO2 mixing with very hot Lithium (-ion or not) fumes plus the normal air in the cargo hold. Perhaps one of the posters has chemistry knowledge and can chime in.

It would also assume that for whatever reason (maintenance or defect) the pressure of the cabin was not higher than the hold as recommended, which I understand may happen, therefore there would be upwards flow from the hold to the cabin.

If, as is posited in this reference, it is possible for CO2 to reach the cabin, what about nitrogen containers instead of dry ice?

Either of these two products (CO2 or Nitrogen) would rob oxygen from the living (whether humans or animals), at the same time as, theoretically, extinguishing any fire. Depending on the contingencies, it may be possible that fire alarms are not triggered because of this.

Boeing Smoke Detection Systems

I do not understand the consequences of the limits of detection of a fire in this article. If a fire occurred in extremely close proximity to a nitrogen container, rupturing it, and if the nitrogen extinguished the fire, would there be enough smoke particles to trigger the dectection systems, while all the nitrogen emptied itself in the hold?

That is assuming that the placement of the goods involved has been made according to regulations - which they may not have been, and assuming also that the distance between the detector and the fire is fairly close which may or not be the case.

This is also assuming that the goods involved are in the hold or baggage compartments - what if they were carried in the cabin? Well maybe not nitrogen or dry ice, too bulky, but some similar hazardous material - one never knows what a passenger has in a bag...

@Max Nightstop

This reference here: Fire Protection Systems explicitly says that Carbon monoxide (CO) detectors do exist.

What I am learning from this reference is that pilots can control the airflows from hold to cabin.

Quote from page 17-18:

Fire detecting sensing elements are located in many high-activity areas around aircraft engines. Their location, together with their small size, increases the chance of damage to the sensing elements during maintenance.

The following reference B777 Air Systems - downloadable pdf file details the air flows in a B777. I do not have the knowledge to analyse this document.

@Yawn
Thank you.

@Fred The Red

Is it safe to assume a) CO couldn't enter cabin (either from known (ie. engines) or unknown (cargo hold fire) combustion sources) and, b) if CO were present, a/c are fitted with appropriate detectors?
From the above references,

(a) no.
(b) I don't know for sure but this would need checking - perhaps cost may limit their use?

@others
Thank you for helping examining this theory.
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Old 24th Mar 2014, 00:15
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I am assuming that the raw data presented reflects directly what was received by the ADS-b ground station.
The last two ADS-b transmission do not have any altitude data (it has presumably been set to zero as there is no valid data).
Your assumption isn't valid. Those are not original ADS-B transmissions, they are FlightRadar24's processed data, originating from enthusiast Mode S receivers with software that may also have done some pre-processing of the raw data as sent by the aircraft.

If you have been involved in ADS-B development, you will know that the message format quoted in your post

T[UTC];LAT[°];LONG[°];HDG[°];ALT[ft];SPD[kts];RoC[ft/mn];Squawk;ADS-B feeder;Data Source
is never transmitted by an aircraft in that form. Positional data (ie lat/lon) and velocity (groundspeed and track) are always sent separately.

So you cannot infer from the absence of individual parameters in a FlightRadar24 pseudo-message that the aircraft was sending null values.
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Old 24th Mar 2014, 00:20
  #7603 (permalink)  
 
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Get on Google Earth and type in Pulau Langkawi and then look at it in relation to the radar track heading. Two plus two equals four.
For you maybe but for me your theory makes little sense. There is no 2+2 = 4 here, at least we are far from any such simplicity.
You have to explain why this aircraft turned sharply South (or North) after exiting the Malacca straits. The aircraft trajectory and its zigzagging even inside the straits makes little sense when compared to possible approaches to Langkawi airport. If on the other hand you claim that the aircraft never exited Malacca straits and crashed somewhere there then you better find it... water there is very shallow, search area limited, it is also a very busy area and pieces should be floating now for everybody to see. By the way your post is exact replica of hundreds identical, not much originality.
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Old 24th Mar 2014, 00:22
  #7604 (permalink)  
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I found 4 or 5 incidents of pilots deliberately flying aircraft with passengers into the ground over 30 years. I haven't tried to figure out how many fatal accidents there've been amongst airlines during the same period, but I know it's way, way more that that. Pilot suicide causes a tiny proportion of what is already a tiny number.
I'll say it again.

There are very few instances of airliners being lost in the cruise with no immediately apparent cause. Of those, the instances of suspected deliberate pilot action form a significant fraction.

There is no statistical argument against it being a possible cause in this case.
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Old 24th Mar 2014, 00:26
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@Control Eng

Is there some way to suppress altitude output? and if so why would someone want to do that when he is disabling the SSR/ADS-b.
Turn off mode c, physically break the connection to, or destroy, the altitude encoder unit.
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Old 24th Mar 2014, 00:44
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No separate encoder, the altitude info comes from the ADIRU. Going to mode A (code) only sending no C or S data will give you a flag (invalid altitude) not 0'

On changing codes...On the digital controllers with rotary knobs, they continue to squawk the old code until several seconds have passed without a change then switch to the new code. IE is you are squawking 4444 and change the first digit to 6, the transponder squawks 4444 til a few seconds have passed, then squawks 6444, no standby in between.

I never tried to enter 3 digits on a push button one, so I can't say what it would do if you only entered 3 digits, but best guess would be it would disregard the change and continue to squawk the old code.
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Old 24th Mar 2014, 00:48
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This would probably indicate decompression or fire.
It could indicate many different things.
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Old 24th Mar 2014, 00:49
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Yankee Whisky

If you read some of the posts of experienced guys on type or similar types, you will see that this explanation does not make sense. Read post from "Albert Driver" Post 7598, where he makes some excellent points.

Also the Zig zag flight, does not make sense with what has happen. Finally if this was true, why did they not attempt the approach?
Because somebody must have been awake to set them on south course after passing airport.
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Old 24th Mar 2014, 01:06
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Originally Posted by Yawn
Assume HDG Mode on 180 until fuel exhaustion.
A 180M track ends up too far east of the present search area. The same case results from a 180M heading (link to winds from Vasquez).

Assuming IGREX as a starting point then the following graphic shows constant magnetic tracks for 180, 190, 200 and 210 degrees.
Disregard the lengths.



180M TRK (text | kmz), 190M TRK (text | kmz), 200M TRK (text | kmz), 210M TRK (text | kmz).
Map here (expires 20140327 at 0000Z).
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Old 24th Mar 2014, 01:35
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A 180M track ends up too far east of the present search area.
The present search area is not the area where the authorities think the plane went down. It is the area to where the authorities think the wreckage will have drifted over the past two weeks. Given that the general direction of drift is eastward, don't discount the 180 track yet.
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Old 24th Mar 2014, 01:42
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Yankee Whiskey, I guess being quoted by numerous media outlets for getting this post up on Wired.com wasn't enough, so now you have to spout you nonsense in full on PPrune too.

My second favorite part of your theory (my first is that the raging electrical fire that killed everyone onboard mysteriously went out, letting the autopilot stay engaged even with no electrical power) is that the PF was headed to Langkawi, even though it was closed, a very dark place to land even when the lights are on, and a one direction runway for approaches (the opposite direction he was heading), Penang was closer (and open 24/7) with approaches on both runways, and full firefighting support. Both pilots had flown into and out of both of these airfields many times, and both knew one was closed one was open. Push the ALT button in the FMC and head direct to PEN.

I am sure you like the "simple" theory since it appears you did minimal research (if any) on B777-200ER's, Malaysian Airlines, or the area in which contact was lost with MH370, because you would have had a much more informed and valid argument if you had.
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Old 24th Mar 2014, 01:44
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To those obsessive adherents to the "aircraft fire" scenario that disabled the crew but left the aircraft flying for many hours afterwards - I have just one question.

Skywriting aircraft produce copious amounts of highly visible smoke from the injection of a relatively small amount of low-viscosity oil into the hot exhaust manifold.
Tyre fires on the ground produce enough black high-density smoke to blanket large areas of cities.

A large aircraft flying at high altitude with a substantial fire on board would produce a smoke-containing contrail so highly visible, it could be seen with a naked eye from the ground - even in early dawn light.
This contrail would surely be highly visible on weather satellite pics, would it not? The projected flight path is over a number of high-traffic shipping lanes. And yet no-one on a ship has reported seeing an extensive smoke contrail?
I look at Tim Vasquez's excellent contrail examination site, and there is only one vague contrail picked up in the Southern latitudes - and this contrail is regarded and examined as a regular contrail - not a smoke-filled one.

I consider that a total lack of any space images showing any contrails from serious amounts of smoke from a major, aircraft-disabling fire, and a total lack of eyewitness reports of smoke contrails, to be a total lack of evidence supporting a fire theory.
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Old 24th Mar 2014, 01:51
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Don't put battery fires out?

I'll leave it to you pilot types to cover the "Pilot Stuff" while I'm turning the spanners !

However, from the PDF someone posted a page or two ago regarding aircraft fire systems,

Page 17-2

Class D—fires involving combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and potassium.


And from Page 17-10

However, do not use Halons on a class D fire. Halon agents may react vigorously with the burning metal.

Anyone got a chemist friend who could comment on what "vigorously" might mean in this event?

What would happen if a small or otherwise controllable lithium-battery fire occurred and the pilot discharged the Halon extinguishing system on it?
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Old 24th Mar 2014, 01:59
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Halon at very high temperatures - um, phosgene, no? Just a little bit poisonous. Halon works well on flames as it is inert and heavier than air. In the case of incendiary Magnesium, Titanium e.g., a bucket of sand is a better way to go. Early Teflon (tm) research by duPont killed at least one scientist when the fry pan under test got a bit too hot. According to the legend.
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Old 24th Mar 2014, 02:11
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Updated diagram

Some refining here...



I refined the initial no wind 197 degree green line track to 200deg M/515 knots GS from the initial point and am pleased to see it closely resembles Selfins much more professional effort which incorporates the winds.

The pink direct track now has hourly markers at 485 GS. From there I extrapolated psuedo-satellite arcs based on the distances from IOR of these hourly markers; the thinking being here that if they were roughly equidistant from each other then there is a good chance that would indicate that the aircraft took a direct track to the search area, taking into account GS changes due to wind changes.

They appear to do that.

Extending the arcs through the initial 188 deg M track and the 200 deg M track reveal large discrepancies at different parts of those tracks, indicating that the aircraft did not take those tracks.

I stress: A lot of this is supposition but it appears to support the case I made earlier that:

The attitude of the Malaysian government that the aircraft was deliberately taken to this area stems from the fact that the evidence supports a direct track taken to reach the initial search area.

A direct track can over that distance can only be practically achieved by a FMC entry due to the massive changes in magnetic variation. That in turn implies technical knowledge and intent.

There is also no reason for a southerly heading to be in the HDG box to send the aircraft south after reaching a route discontinuity, particularly as this would have have to be been turned that way over an hour after contact was lost.

I acknowledge the suppositions. There are many technically/mathematically inclined people reading this who can possibly comprehensively disprove those assumptions if they are flawed. Please feel free to do so if you are able.
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Old 24th Mar 2014, 02:11
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Lithium battery-Halon fire tests-PowerPoint file from FAA:

www.fire.tc.faa.gov/ppt/systems/lithium%20bat%20060602.ppt
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Old 24th Mar 2014, 02:13
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Pardon my ignorance but if there was something at the bottom of the ocean surely the MAD in the Orions would find it?
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Old 24th Mar 2014, 02:19
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@DaveReidUK

Can you please check were I stated that I
have been involved in ADS-B development
or that these were
original ADS-B transmissions
or that I inferred that the messages were
transmitted by an aircraft in that form
as you yourself quoted, I said
I am assuming that the raw data presented reflects directly what was received by the ADS-b ground station
ATC systems receive ADS-b data from ground stations over data links. The links transfer data packages that contain combined squitters of ADS-b transmissions.

The data package formats were ADS-b receiver manufacturer specific but content wise were remarkably similar to those displayed, however they did have validity flags.

I am fully aware that FR24 relies on enthusiast Mode S receivers but am amazed that you seem to consider that this particular programmer was astute enough to be able to write a program that selected just these two particular messages to drop the altitude (while keeping the lat/long from the same squitter) when all his other messages were presented in totality.
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Old 24th Mar 2014, 02:23
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"I found 4 or 5 incidents of pilots deliberately flying aircraft with passengers into the ground over 30 years. I haven't tried to figure out how many fatal accidents there've been amongst airlines during the same period, but I know it's way, way more that that. Pilot suicide causes a tiny proportion of what is already a tiny number. "

I'll say it again.

There are very few instances of airliners being lost in the cruise with no immediately apparent cause. Of those, the instances of suspected deliberate pilot action form a significant fraction.

There is no statistical argument against it being a possible cause in this case.
No. It is of course a "possible cause." But there is an argument against it considered being more likely than other highly improbable causes. The difference between 1 occurrence in 1 million of explanation A and no occurrences of Explanation B in the same one million is not significant enough to make predictions about whether A or B is more likely to have actually happened in a given case.
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Old 24th Mar 2014, 02:24
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@titania

To give an idea of just how nitrogen can be toxic
80% of the air we breathe is Nitrogen. It's only poisonous at great pressure such as deep-sea diving.

At sea-level pressure or lower it can only harm by displacing normal air completely and so eliminating the oxygen.

Gases that can kill or render unconscious are rare in aircraft. As you point out CO - Carbon Monoxide is one.

Another one very relevant to aircraft is HCN gas - Hydrogen Cyanide. It's a by-product of heating certain types of plastics and was the primary cause of death in at least one otherwise survivable accident - where a plane crashed and a small fire started that generated smoke and HCN from seat cushions that killed most passengers before they could exit.

However HCN would be very unlikely to be generated without large amounts of smoke.
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