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Better Black Boxes on Airliners


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#1 Airbrush

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Posted 21 March 2014 - 05:54 PM

I posted this in "Politics" but I want engineering geeks to help me out with this.

In this age of advanced communications and cheep GPS in cars and cell phones, it seems stupid that airliner black boxes are so ineffective, as seen in the disappearance of flight 370. So make them smarter. There should be a redundant number of them on every airliner, scattered about the plane, and attached to the OUTSIDE of the plane. Nobody connected to the plane can turn them off. (There should also be something on the plane that cannot be disabled that CONSTANTLY transmits GPS location.) Why we don't have this is because often times stupidity is the norm until humans are FORCED to improve. Look at the endless media attention on this matter.

When these smart black boxes detect catastrophic motion, they go into action. They should eject from the plane at the correct moment, inflate, and give off signals so the location of the crash can be quickly discovered. They should be small and cheep, maybe only a foot in diameter after inflated. The inflatable buoy should be made of tough, flame-resistant material, weighted on bottom so solar cells on top can power it, and the transmitter is above water.

Someone said it would be too expensive.

I'm sure engineering experts can think of something.

Edited by Airbrush, 21 March 2014 - 06:00 PM.

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#2 John Cuthber

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Posted 21 March 2014 - 06:40 PM

I think the current situation might convince the airlines that they should include a better "black box".

It's been said (in the other thread) that most GPS systems only receive.

That's true, but not the point.

A satellite 'phone isn't that expensive (compared to a jet plane) and any GPS device could tell it where it is.

The technology is off-the-peg these days.

One potential problem is that the military get shirty about GPS systems that work when moving fast and at high altitude.


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#3 CharonY

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Posted 21 March 2014 - 07:25 PM

Well, a satellite system would work and it would basically only need to send out the last GPS coordinates. If it only kicks in after an accident (when the plane is not moving anymore) the movement should not be an issue. Unless it is used as position device but I am wondering whether there are not equivalent technologies already in place to track plane movements during routine travel. What I am also wondering is whether existing satellite comms would work under water.

 

Edit: scratch that. I just remembered that transponders have been used to track sharks, so that should work, unless I am missing something. 


Edited by CharonY, 21 March 2014 - 07:51 PM.

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#4 Enthalpy

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Posted 21 March 2014 - 08:36 PM

I wouldn't separate the black boxes from the plane. Floating objects drift away quickly. Worse, they would separate, or lose the power supply or data link, when they shouldn't.

 

At the plane's tail, they aren't accessible.

 

A radio transmitter is easily located. It doesn't have to know and tell its position. Argos for instance did it before GPS existed.

 

Impossible to turn off: you've seen one advantage to it in one circumstance. I'm confident it would have drawbacks in many other circumstances. And more generally, aviation relies broadly on humans that are intelligent, responsible, and of good will. This works not too badly up to now. Introducing hardware that resists human intention will probably make things worse. If you want to factor bad intentions in, don't forget it happens often on the ground.

 

What can be done, as I suggested after AF447, is let them emit sound at low frequency, not as a high-pitched sound or ultrasound. Low frequencies propagate better in the Ocean, and a known noise would be detected hundreds or even thousands of km away by submarines.

 

Presently, we ignore where MH370 is. Inhabitants of southern Maldives believe to have seen it. Then it may not be a matter of black boxes at all.

 

Even more than a matter of black boxes, if I were a military in southern Asia, I would worry about radars and air defences. Losing an airliner over an achipelago is a bad sign. The transponder was off: does anyone expect an assailant to wear a transponder?

 

I also doubt that the airliner's track was really lost. For instance, Inmarsat got a last "position" (somewhere on the two arcs), but it got some more every hour before - that should enable to reconstruct a path, shouldn't it? And, yes, spy satellites exist, their performance is hugely better than a few pixels on a 25m object, there are so many that no hole exists in their coverage. Once the commercial sat detected a spot (it looks unconvincing), spy satellites could have made perfect pictures of it, located it exactly, and radar satellites would tell if the object is metallic. I don't buy the story that the Indian Ocean is a terra incognita where one can lose an airliner, sorry.


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#5 Danijel Gorupec

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Posted 21 March 2014 - 09:26 PM

...

 

What can be done, as I suggested after AF447, is let them emit sound at low frequency, not as a high-pitched sound or ultrasound. Low frequencies propagate better in the Ocean, and a known noise would be detected hundreds or even thousands of km away by submarines.

 

...

 

Even more than a matter of black boxes, if I were a military in southern Asia, I would worry about radars and air defences. Losing an airliner over an achipelago is a bad sign. The transponder was off: does anyone expect an assailant to wear a transponder?

 

I am not that sure the low-frequency sound would work very well for black boxes. I suppose that you would need a rather large device to emit a loud low-frequency sound. I also suppose that lot of energy will be needed.

 

For the second part I completely agree... It is funny that the military missed this plane. Very embarrassing.


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#6 Airbrush

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Posted 21 March 2014 - 10:11 PM

Yes, a radio transmitter or a satellite phone.

There should be a tamper-proof transponder, that cannot be shut off by unauthorized people.

Even a system of smoke-flare-buoys might be enough to get the attention of search parties, who already know the general area the plane went down from the transponder info. If the buoy can make smoke for 24 hours, it might be long enough. Even if the buoys drift a long way from the wreckage, we can figure out where the wreckage is judging from the speed of local water currents and recorded data of time and location of impact.

And forget about solar powered, use a heavy duty truck battery for your radio transmitter.

Edited by Airbrush, 21 March 2014 - 10:16 PM.

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#7 Airbrush

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Posted 22 March 2014 - 02:56 PM

A transmitter attached to heavy wreckage, or a sinker device, is attached by a wire 2.5 miles long. That should be long enough to connect the smoke buoy to the wreckage on the bottom of most oceans. In the Marianna's Trench, sorry you're out of luck.

And all these efforts to find wreckage isn't going to save your life, if you were a passenger, so have all seats like a piston at the top of a cylander. People can eject out of the bottom of the plane and use a parachute attached to the seat. Heck, even have an oxygen mask attached to your seat. I might pay a little more for my ticket if the airline boasted of these safeguards.

Edited by Airbrush, 22 March 2014 - 02:59 PM.

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#8 Danijel Gorupec

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Posted 22 March 2014 - 03:49 PM

Not trying to be a party pooper, but maybe we are mixing apples and oranges...

 

Planes may need better tracking devices to help us find the wreckage site faster. But this tracking is not the job of the Black Box.

 

The black box is used to provide aftermath insight - to help us build better equipment and better procedures in order to prevent future failures. The black box has a transmitter device so that the box itself can be found withing the scope of the wreckage site. Its transmitter is not intended as a long-range guide to the wreckage site (they are trying to locate the wreckage site by searching for the black box signal only because they are desperate enough - this is how I see it).


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#9 Cap'n Refsmmat

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Posted 22 March 2014 - 04:11 PM

And all these efforts to find wreckage isn't going to save your life, if you were a passenger, so have all seats like a piston at the top of a cylander. People can eject out of the bottom of the plane and use a parachute attached to the seat. Heck, even have an oxygen mask attached to your seat. I might pay a little more for my ticket if the airline boasted of these safeguards.

You'd pay quite a lot more, since the airplane wouldn't be able to carry cargo with passengers ejecting through the hold.

 

Military pilots get extensive training on landing with a parachute and surviving in the ocean, desert, or wherever they may come down.

 

Also, what fraction of aircraft accidents are the sort where the passengers would be able to eject?


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#10 John Cuthber

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Posted 22 March 2014 - 04:22 PM

I understand that passengers are so unconcerned about safety that they won't even accept rear-facing seats.

Good luck trying to get them to pay for ejector seats .


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#11 Airbrush

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Posted 24 March 2014 - 12:09 AM

You'd pay quite a lot more, since the airplane wouldn't be able to carry cargo with passengers ejecting through the hold.
 
Military pilots get extensive training on landing with a parachute and surviving in the ocean, desert, or wherever they may come down.
 
Also, what fraction of aircraft accidents are the sort where the passengers would be able to eject?


Revise the design of the plane so that passengers are on the lower level and cargo is the upper level. This way everyone can slide down through a chute in the floor, to facilitate many people exiting in a short time.

No training necessary if everyone is securely stapped to a parachute that automatically deploys at the right time. At least they will have a chance at survival, rather than certain doom.

Even if only a small fraction of accidents would lend to this, people would feel better to know they had SOME kind of chance at survival (no matter how unlikely). Airlines that had this safety system would have an advantage over airlines that DON'T CARE ABOUT PEOPLE.

Edited by Airbrush, 24 March 2014 - 12:10 AM.

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#12 Enthalpy

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Posted 24 March 2014 - 12:49 AM

 

I am not that sure the low-frequency sound would work very well for black boxes. I suppose that you would need a rather large device to emit a loud low-frequency sound. I also suppose that lot of energy will be needed.

 

A transducer smaller than the wavelength is slightly less efficient (there are tricks), but the attenuation in water is much more important.


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#13 Cap'n Refsmmat

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Posted 24 March 2014 - 12:57 AM

Revise the design of the plane so that passengers are on the lower level and cargo is the upper level. This way everyone can slide down through a chute in the floor, to facilitate many people exiting in a short time.


Airplanes are cylindrical tubes. The lower level is hence narrower. For example:

640px-Airbus_A300_cross_section.jpg

So you'd fit fewer passengers on the plane. That's quite a big cost. And what about landing gear failure? That's fairly common, and now you'd have the passengers bear the brunt of the impact.
 

No training necessary if everyone is securely stapped to a parachute that automatically deploys at the right time. At least they will have a chance at survival, rather than certain doom.

So you have to put everyone in a five-point harness with pyrotechnic devices to fold the tray tables out of the way. They can't put their backpack or purse under the seat in front of them, in case it gets in the way of ejection. You also have to supply a life raft or survival gear for every seat, in case they come down over water.

Also, landing under parachute without training is a great way to break an ankle or a leg.
 

Even if only a small fraction of accidents would lend to this, people would feel better to know they had SOME kind of chance at survival (no matter how unlikely). Airlines that had this safety system would have an advantage over airlines that DON'T CARE ABOUT PEOPLE.

Airplanes are already safer than cars, buses, or trains per mile traveled. Aviation safety is great.

The FAA uses an interesting system for cost-benefit analysis. Every passenger's life is assigned a monetary value, and the cost of the safety measure weighed against the expected passenger value saved. Ejection seats would be fantastically expensive and mostly ineffective.
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#14 Enthalpy

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Posted 24 March 2014 - 12:58 AM

[...] tracking is not the job of the Black Box.

 

Presently not, but if we can in the future  find a wreckage thanks to the black boxes, of course it should be done.

 

For AF447, the black boxes were at 3,000m depth, where their high-pitch sound provided zero help to locate them. It took two years. A low-frequency sound would have been heard not only from the surface, but from a long distance.

 

====================

 

The Boeing 777 has one single data network for flying the plane and to move data for the passengers. That's plain foolish. Have we seen now the first case of hijacking by tampering the network? With some transmitter-receiver on board it could even have been made remotely.


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#15 swansont

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Posted 24 March 2014 - 11:51 AM

Airplanes are already safer than cars, buses, or trains per mile traveled. Aviation safety is great.

The FAA uses an interesting system for cost-benefit analysis. Every passenger's life is assigned a monetary value, and the cost of the safety measure weighed against the expected passenger value saved. Ejection seats would be fantastically expensive and mostly ineffective.

 

Indeed. Odds of being killed on a single flight are extremely low.  There are thousands of flights per day in the US alone. We're talking about one incident out of tens of millions of flights in just the last few years. What's the risk/reward profile? 

 

More than half of airline accidents happen on takeoff/initial climb or final approach/landing. No real chance of ejection.

http://www.statistic...ash-statistics/


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#16 Airbrush

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Posted 24 March 2014 - 06:31 PM

I sure appreciate all the advice above.  Thanks for the info.   Nice cross section Capt Ref, very interesting.

 

My last gasp, and then I give up, at this will be to suggest that when you buckle your seat belt you are fastened to a parachute that is inside the seat, but will disengage from the seat.  Rather than an expensive seat ejection system, when someone authorized hits the panic button (only in case of imminent disaster), the parachute separates from the seat.  Each passenger, who wants to live, buckles a couple more buckles to be securely fastened to your parachute/floatation device.   Then anyone who wants a chance at living, forms a line for the escape chute and slide through a tunnel out the bottom of the plane.   The parachute opens automatically after a few seconds of free fall.   Of course there would be an emergency rip cord to pull, just in case it does not automatically deploy.

 

Or I will suggest this again in a decade. :-)


Edited by Airbrush, 24 March 2014 - 06:35 PM.

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#17 John Cuthber

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Posted 24 March 2014 - 07:15 PM

"when someone authorized hits the panic button"

Does anyone have the stats for "pilot error" handy?

 

"Then anyone who wants a chance at living, forms a line for the escape chute and slide through a tunnel out the bottom of the plane."

Then lands in the cold water and dies of hypothermia  or gets eaten by sharks. (or, indeed, both).

Temperature distribution

http://www.epa.gov/c...rface-temp.html

 

effect of cold water immersion

http://www.seagrant....ies/hypothermia

 

Plan A 

Don't let planes crash.


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#18 Enthalpy

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Posted 24 March 2014 - 07:31 PM

More about the pingers. There is one attached to each black box.

Whole world listens for slowly fading pings - CNN.com

Frequency is 37.5kHz, a horrible choice. Ceramic buzzers exist at this frequency, so some electronics designer must have picked it for no other reason. The range is 2 nautical miles, that is the depth of the mean Ocean floor only.

 

As opposed, a sonar has a range in the hundreds of nautical miles, because it uses a low frequency that propagates in sea water. It transmits kilowatts, but the target reflects very little power (<<1µW), far less than a battery permits.

 

Then a helicopter can dip a receiver, listen, and fly much futher to the sides, then land on its boat to refuel and change the crew. The boat makes the forward move. This is efficient search.

 

Also, batteries exist that run on a chunk of magnesium, a little bit of iron, and sea water as the electrolyte. They wouldn't work alone in a forest, but provide in the sea much more energy per mass unit than other batteries.


Edited by Enthalpy, 24 March 2014 - 07:54 PM.

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#19 swansont

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Posted 24 March 2014 - 09:02 PM

Of the small number of plane crashes, how many happen over the open ocean, where a sonar-friendly pinger would be useful?


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#20 Enthalpy

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Posted 26 March 2014 - 07:11 PM

We're talking only about crashes. They aren't common, but the black box serves in this case. So whether the pinger should be made audible far away relates more to "what proportion happens in deep Ocean", I'd say.

 

While half of all crahes happen at landing and take-off, an interesting proportion of the other half happens in the oceans, as these cover most of our planet.

 

We could make the comparison an other way: consider how many planes, boats and people try to locate MH370, or previous debris before. This looks more expensive (and money isn't the only criterion) than putting better pingers on black boxes.


Edited by Enthalpy, 26 March 2014 - 07:12 PM.

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