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Aircraft Accidents Due To Bad Air?

By SEWilco in Technology
Thu May 24, 2001 at 12:08:19 AM EST
Tags: Science (all tags)
Science

A geologist points out that some aircraft incidents may be due to airliners flying into huge gas emissions.


Thomas Gold has observed that some aircraft incidents have taken place in areas which are likely to have emit large gas clouds. These clouds may be volcanic plumes or lighter-than-air methane. There obviously can be interesting effects when jet engines encounter something other than normal air, particularly if it's flammable gas. He points out three known events of volcanic clouds stopping all of an aircraft's engines.

The National Transportation Safety Board Accident Data does not have a category for problems with the air itself. There have been assorted earthquakes along the NE coast of the USA, one area of interest. The edge of the continental shelf also happens to be where methane hydrate deposits exist, and a survey found the area along the NY coast to be charged with gas.

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Poll
I Can Deal With Hot Air
o by never flying off this continent 5%
o by flying out of JFK only after a hurricane 0%
o by staying above the atmosphere 23%
o by only walking with an open flame 17%
o by reading /. with a high cutoff level 44%
o by watching my Al Gore DVD inflight 9%

Votes: 52
Results | Other Polls

Related Links
o huge gas emissions
o Thomas Gold
o Accident Data
o assorted earthquakes
o methane hydrate deposits
o charged with gas
o Also by SEWilco


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Aircraft Accidents Due To Bad Air? | 26 comments (23 topical, 3 editorial, 0 hidden)
Ships (3.70 / 10) (#1)
by Bad Harmony on Mon May 21, 2001 at 04:57:57 PM EST

I saw a documentary on TV that proposed a similar mechanism for the unexplained sinking of ships. Underwater landslides can release large amounts of methane, reducing the specific gravity of the water, producing negative buoyancy for the ship. This has already happened to some off-shore oil rigs.

5440' or Fight!

Bermuda Triangle Myth (3.00 / 2) (#2)
by SEWilco on Mon May 21, 2001 at 05:12:16 PM EST

Must not have been the BBC's "The Bermuda Triangle". It could happen but because a large number of ships have not sunk there, there is no mystery.

[ Parent ]
Similar mechanism suspected in North Sea, Africa (4.00 / 5) (#4)
by kmself on Mon May 21, 2001 at 05:55:20 PM EST

Gas Leak May Solve Riddle of North Sea Triangle Thursday, November 30, 2000. I'd heard of this some time back. A Google search turns of some additional references: 'Giant Bubbles' caused disasters and Media Watch - 'Giant Bubbles' caused disasters.

The phenomenon isn't limited to ocean areas. I first heard the following story from a friend who'd been doing Peace Corps work in the area. An African lake erupts in CO2 periodically, filling a valley (CO2 is about 1.5 times denser than air) to a distance of 23 km, moving at speeds of 20 to 50 km per hour, killing nearly all oxygen-breathing lifeforms in the area. The Lake Nyos expulsions are thought to have on the order of a few times a century. Similar lakes dot the region.

In the US, the Mammoth Lake area, a popular skiing and backpacking region of the Sierra Nevada, is volcanically active. There are several lakes and valleys which have significant CO2 emissions, and in which visitors are warned not to stay overnight or spend time in enclosed quarters -- buildings or tents. Concentrations are sufficiently strong to kill forests.

--
Karsten M. Self
SCO -- backgrounder on Caldera/SCO vs IBM
Support the EFF!!
There is no K5 cabal.
[ Parent ]

Carbonated Lake (4.42 / 7) (#5)
by SEWilco on Mon May 21, 2001 at 10:00:09 PM EST

That killer lake in Africa is being treated. Several months ago a pipe was installed between the bottom and the surface. A little pumping to get the flow going...the carbonated water from the bottom began moving upward in the pipe, the pressure was reduced enough to bring the carbon dioxide out of the mix, the resulting bubbles push the water/gas mix up and sent it fountaining out the top pipe. Just as expected. Enough pipe/fountains will be installed to let the self-sustaining pumping eliminate the buildup.

[ Parent ]
Why would CO2 kill forests? (5.00 / 1) (#18)
by DaBunny on Thu May 24, 2001 at 11:22:44 AM EST

Why would higher concentrations of CO2 kill plant life? If I remember high school biology, plants use CO2, instead of creating it as a waste product. Obviously high CO2 levels would be very bad for oxygen-breathing animals, but for plants?

I'm not questioning that it does, just wondering about the mechanism.

[ Parent ]

From the linked page (3.00 / 1) (#20)
by krlynch on Thu May 24, 2001 at 01:23:20 PM EST

From the linked page:

Although oxygen deprivation (ref. 7) may be involved in the tree kills, inhibition of root function by CO2 (ref. 8) is probably more significant. The threshold [CO2] and time factor needed to cause mortality in these coniferous trees are not known, but the area presents a useful natural laboratory to study the effects of anomalous CO2 increases on vegetation. Studies elsewhere have generally shown that elevated [CO2] in the local atmosphere enhances photosynthetic rate (G. Koch, personal communication) and that some plants can adapt to permanently high soil [CO2] (F. Miglietta, personal communication), but the sudden large increase in root-zone [CO2] and forest die-off distinguish the Mammoth Mountain case. Dead tree ages range up to ~250 yrs, suggesting that these kill areas have not experienced a similar CO2 anomaly for at least 250 yrs.

[ Parent ]

CO2 killing plants (4.00 / 1) (#24)
by Tsuraan on Mon May 28, 2001 at 10:03:16 PM EST

I'm just remembering this from high school biology, so it could be a bit off, but here goes. Plants have two metabolic cycles. One of them is the light cycle, where the plants use the sun's energy to convert CO2 to O2 and fructose (or whatever else they use carbon for). The other cycle, however, is nearly identical to that of animals. This is how they regenerate ATP, and it uses oxygen. Without any oxygen at all, plants will die, but unlike animals, they create it on their own, so they can live in a sealed environment for a lot longer than animals can.

[ Parent ]
What about perimeter effects? (none / 0) (#17)
by jkeene on Thu May 24, 2001 at 09:43:49 AM EST

Did the documentary have any information on near-sinkings, for ships just at the edge of the affected zone? Seems like there should be at least a few reports of being on the edge of one of these incidents.

[ Parent ]
Sounds like uninformed speculation to me (4.68 / 16) (#3)
by FlightTest on Mon May 21, 2001 at 05:31:51 PM EST

Plumes of volcanic ash flaming out engines is not new. The Airman's Information Manual specifically warns against flying into areas of volcanic ash. Also, he says

I had investigated in 1982 a "near disaster" of a British Airways 747 plane flying at 37,000 ft over a volcanic region of Java. All four engines stopped shortly after it had entered a visible but tenuous volcanic cloud. After gliding down to 15,000 ft without power, and there apparently leaving the cloud, all engines could be started again immediately.
I'm not familar with the operation of the 747, but it may very well be that you have to descend to 15,000 to get a relight anyways. If the aux. power unit is not on and all 4 flame out, you'd be forced into trying an air start. This requires quite a bit of airflow through the engine to turn it fast enough to support combustion.

He doesn't explain how, if TWA 800 was caused by an external methane cloud, why the wreckage of the aircraft clearly indicated the origin of the blast being inside the aircraft. The damage patterns on the aircraft skin would be quite different if the inital explosion was outside the aircraft. He tries to link Swissair 111 into this theory of his, yet pretty much everyone, including the manufacturer, are pretty much conviced that an in-flight fire caused by faulty wiring was the culprit.

The theory seems to change as it goes as well. First he claims the rising bubble of methane is rising so fast that it could structurally damage the aircraft. Then it's rising slowly enough that the Egypt Air crew has time to push the nose over and build up enough momentum in the thin air that upon exiting the bubble the aircraft is well over it's dive speed. And aircraft airspeed indicators are simple dynamic pressure instruments. It doesn't matter if it's air or methane. If such a large bubble of low density gas encompased the airplane, the airspeed indicator would have showed a huge drop in airspeed, and the altimeter a huge increase in indicated altitude. Alas, neither of these indications are present on the flight data recorder.



Why did I flip? I got tired of coming up with last minute desparate solutions to impossible problems created by other fucking people.
Good Points (4.50 / 4) (#6)
by SEWilco on Mon May 21, 2001 at 10:09:56 PM EST

So maybe the present mystery is what the satellite pictures are showing. And if there are methane bubbles popping up, we might have been lucky that there haven't yet been unrecoverable incidents (there could have been unidentified turbulence incidents caused by this).

I suppose a study could look back in time -- find time/location of those bubbles and check for aircraft which were in the vicinity of a bubble (not easy, but FAA/NTSB have radar playback equipment). If an aircraft was in, or near, a bubble, then see what happened in that situation.

[ Parent ]

Tapes only saved for 15 days (4.50 / 2) (#8)
by FlightTest on Tue May 22, 2001 at 04:57:35 PM EST

I suppose a study could look back in time -- find time/location of those bubbles and check for aircraft which were in the vicinity of a bubble (not easy, but FAA/NTSB have radar playback equipment). If an aircraft was in, or near, a bubble, then see what happened in that situation./

A good idea, except that ATC voice and radar tapes are only preserved for 15 days, unless there is an accident, incident, or investigation that causes them to pull the tapes and preserve them. I'm only talking U.S. here, I have no clue how long or even if the rest of the world keeps such things. Also keep in mind that over large areas of the world, especially the oceans, there is *NO* radar coverage.

So maybe the present mystery is what the satellite pictures are showing. And if there are methane bubbles popping up, we might have been lucky that there haven't yet been unrecoverable incidents (there could have been unidentified turbulence incidents caused by this).

Personally, I think before we start worrying about how this may be affecting airplanes, we should determine what the phenomena really is, or if it even exists at all.



Why did I flip? I got tired of coming up with last minute desparate solutions to impossible problems created by other fucking people.
[ Parent ]
Microbursts (4.33 / 6) (#7)
by kmself on Tue May 22, 2001 at 12:17:55 AM EST

A related phenomenon is microbursts, which have been implicated in a number of airplane accidents, including Delta 191. The wind sheer associated with microbursts initially increases an aircraft's apparent airspeed. As a result, many pilots would compensate by cutting their engines. Unfortunately for them, this is followed by a downdraft, then a tailwind, the net result of which is a rapid loss of altitude, airspeed, and lift. National Geographic had a really good issue on this topic in the 1980s. What happens in a microburst is that you're essentially shooting a stream of air straight down. The air has to go somewhere when it hits the earth's surface, and that somewhere is out. Hence the headwind / downdraft / tailwind profile.

A similar logic might apply to a gas pocket. There would be an initial turbulent episode as the craft flew into the rising bubble, an increase in altitude, then a second turbulent episode and sudden loss of lift.

I'm not sold on the story, though it's interesting.

--
Karsten M. Self
SCO -- backgrounder on Caldera/SCO vs IBM
Support the EFF!!
There is no K5 cabal.
[ Parent ]

Microbursts (4.66 / 3) (#9)
by FlightTest on Tue May 22, 2001 at 05:23:40 PM EST

Yes, and microbursts are now a well-known phenomena, thanks mainly to the accidents that they caused. Despite certain media personalities protestations to the contrary, the NTSB is actually quite good at investigating accidents and incidents and determining what happened. I've seen some amazing documentaries on how the NTSB has pieced together accidents with very little to go on.

Microbursts are a good example. There were a string of accidents, low to the ground, in the vicinity of thunderstorms, where just the phenomena you described happened. A sudden increase in headwind, causing the airplane to ballon above glidepath; the crew reducing power to get back on glidepath; and a sudden shift to a tailwind, dramatically decreasing lift, and causing the aircraft to sink. With the engines at idle, there isn't enough time to spool them back up to recover before impact. In fact, in the Delta crash, the captain knew what was going to happen. He'd seen it before and warned the first officer that he was going to lose the headwind. Obviously, he didn't know how powerful that microburst was or he'd have aborted the approach.

But there is no string of accidents with similar conditions that lend any credence to this methane bubble theory. TWA 800, Swissair 111 and Egypt Air are way too dissimilar to try to link them the way he has. I'll wait until I see at least a rational, coherent theory from someone who seems to understand the basics of flight before I give this any more consideration. Until then, I'm lumping him with the loonies promoting the idea of a FBI/Navy conspiracy to shoot down TWA 800.



Why did I flip? I got tired of coming up with last minute desparate solutions to impossible problems created by other fucking people.
[ Parent ]
Volcanic Ash and jet engines don't mix (3.50 / 2) (#23)
by gmcraff on Fri May 25, 2001 at 04:17:00 AM EST

Here's why the Airman's information Manual says to avoid volcanic ash clouds:

Volcanic ash tends to be freshly congealed motlen rock. As it solidifies on the fly, as it were, it hasn't has a chance to have any of the sharp edges knocked off of the grain. When injested into a jet engine, this has the effect of sand-blasting the compressor blades, which, in addition to the forward sped of the aircraft, are spinning at a fantastic rate. This has the unfortunate effect of altering the shape and structureal integrity of the blades.

Thus, aside from the problem of clogging the engine, if you are lucky enough to restart the engine without one of the blades breaking and ripping out the side of the engine, you've still got to replace the whole thing because it is unsafe to fly in its uncertain state. And jet engines, ladies and gentlemen, are VERY expensive.

[ Parent ]
Bad air! Naughty air! Sit! (2.33 / 3) (#11)
by jd on Wed May 23, 2001 at 08:37:19 AM EST

Can I put in a plea for a certain, ummmm, international treaty that's supposed to reduce man-made gas emissions?

Since the majority of artificially-generated gas emmissions take place in the same region as the majority of aircraft flights, if there is any link between the two (please note: I'm NOT saying that there definitely is), refusal to comply with the treaty is directly equivalent to the deliberate endangering of aircraft and their passengers.

If there are any environmentalists reading Kuro5hin, who also have the necessary time, I'd like to recommend that someone do the work on this. If there is even the remotest possibility that the current environmental policy can kill, this needs to be known, along with just what that risk is.

Learn! Speak! (4.00 / 1) (#13)
by SEWilco on Wed May 23, 2001 at 11:15:53 AM EST

If you'll read the first link, this is talking about huge bubbles of flammable gases. A manmade emission of that size would flatten nearby buildings as it expanded to cover the city within minutes (as well as incinerate the city if it ignited).

If you'l look at the "methane hydrate deposits" link, the chart on the bottom shows that there's 100 times more methane in hydrates than there presently is in the atmosphere. As those are in cold deep water, pressure or temperature changes can suddenly release huge amounts. Actually, because methane is more of a greenhouse gas than carbon dioxide, it is best if such bubbles do get ignited -- that converts the methane to a little carbon dioxide and a lot of water vapor (the Earth's major greenhouse gas, but there's a lot of it so a little more won't matter).

[ Parent ]

Take Gold with a pinch of salt (3.75 / 4) (#15)
by Lode Runner on Thu May 24, 2001 at 12:32:35 AM EST

Although this theory is fascinating I'm afraid that we must take Thomas Gold with a pinch of salt. Gold has a long history of contrarian, and sometimes downright wacky, theories.

My favorite piece of Gold contrarianism is his proposition that there is petroleum on Venus and Mars. This claim is derived from an elegant theory in which Gold stands on its head the widely-accepted idea that petroleum (and other fossil fuels) is the product of decayed organic matter. In a nutshell, Gold posits that life is derived from petroleum. Consequently, petroleum was here on Earth before life arose and therefore there's no reason it can't be found on Venus or Mars. So we must turn to space to solve our terrestrial energy problems...

But this only scratches the surface of Thomas Gold. If you're at all interested in learning more about Gold's theories (good, bad, and ugly), I suggest you have a look at Oliver Morton's Wired article "Fuel's Paradise".



interesting article, was it the same one you read? (1.00 / 1) (#21)
by cory on Thu May 24, 2001 at 07:06:04 PM EST

The article you link to quotes Gold as saying there are hydrocarbons on Mars, but certainly none on Venus as it's too hot. He also doesn't advocate turning to space to solve our "energy problems", he says we don't have any energy problems to start with, that there's so much oil buried deep that we won't run out for hundreds of years.

Given his history of coming up with crackpot ideas that turn out to be right, I'm willing to give him the benefit of the doubt on this one. The fact that his theories about oil bare out in practice just makes it that much easier to accept.

Cory


[ Parent ]
Read Some More (none / 0) (#22)
by SEWilco on Thu May 24, 2001 at 09:30:43 PM EST

Wired: "But this is one Gold theory that very few agree with. Conventional petroleum geologists hold that hydrocarbons are created by the burial of organic material to depths where moderate levels of heat and pressure "cook" it into oil and gas, which then migrate through the crust to the sorts of sedimentary structures best suited to trap them. Geochemists argue that the bulk of the world's hydrocarbons couldn't possibly reside in the Earth's mantle, as Gold posits; at that depth, hydrocarbons would react with the mantle, oxidizing into carbon dioxide, a process which, Gold's foes believe, is evident in the belching forth of carbon dioxide from the Earth's volcanoes."

But geochemists say that there is carbon all the way to the Earth's core.



[ Parent ]
Gas and piston engines (2.00 / 1) (#16)
by gordonjcp on Thu May 24, 2001 at 09:02:30 AM EST

A couple of years ago, the UK aviation magazine Pilot had several letters about NOTAMs for gas venting areas, and restricted areas above gas processing plants (where inflammable gas may be vented). There was a lot of discussion about the effects of gas venting on petrol engines. Consensus was that flying a piston-engined aircraft through gas might cause the engine to over-rev. I thought this seemed unlikely, as the fuel/air ratio would be disturbed and the engine would rich-cut.
One night, after the pub, a couple of us decided to test this. We set up a lawnmower engine on the workbench, and arranged to be able to feed it petrol, Calor Gas (butane) or both.
Running on petrol, the engine started and ran quite happily.
Running on butane, the engine, again, started and ran.
Starting on petrol, then introducing some butane, stopped the engine. Until we tried with the engine running at nearly full throttle. *Then* when we turned the gas on a big flame came out the exhaust, singing the wall quite spectacularly.
So avoid overflying gas venting areas, basically.

Give a man a fish, and he'll eat for a day. Teach a man to fish, and he'll bore you rigid with fishing stories for the rest of your life.


what about gliders then (1.50 / 2) (#25)
by B'voYpenburg on Thu May 31, 2001 at 07:17:26 AM EST

I guess gliders would be allowed in those areas :-). They don't have engines (allright, some of 'm do) so they can safely fly in gas-venting-plant-areas.

[ Parent ]
With Oxygen (none / 0) (#26)
by SEWilco on Thu May 31, 2001 at 11:31:53 AM EST

The size of human-scale gas emissions is unlikely to be large enough to be significant. Of course, a glider might make use of whatever updraft it finds. But if it's not a normal air mix the pilot may need oxygen. Not that an oxygen source would be a good idea if it's a flammable gas.

And if a glider pilot is over a geologic-scale emission which is visible because it has ignited, I doubt the pilot will want to hang around to hope that the fireball cools off before it reaches his altitude.

[ Parent ]

Huge gas emissions (2.25 / 4) (#19)
by Wondertoad on Thu May 24, 2001 at 01:12:54 PM EST

When I was in college, my roommates accused me of emitting huge gas clouds that could take down a 747. But my diet has improved since then.

Aircraft Accidents Due To Bad Air? | 26 comments (23 topical, 3 editorial, 0 hidden)
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