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Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

theguardian.com

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Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#161

Post by fnordfnordfnord »

wglb wrote: post #156
fnordfnordfnord wrote: post #155

Earlier quoted context omitted.

Under what conditions in an airplane's flight routine is there no radio propagation on any frequency?

From my comment ancestor to this thread: Keep in mind that over-the-horizon radio communication is subject to the vagaries of the ionosphere and is not totally reliable. Non-line-of-sight radio communications are short wave (well, also medium wave and long wave, but those modes require significant power). If ionospheric conditions are bad, as they are at many times of day (worse at night for some bands), at many time…

>So to put a number to your question "likely better than half the time".

I'm not sure how you get from 'because communications between arbitrary point A and and arbitrary point B are sometimes impossible on band C' that "likely better than half the time" communication will be impossible on every useful band to any useful place.

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#162

Post by bryonics »

Plane designed to carry more than 20 passengers: Require three modified spot satellite transmitters, self activating on power loss, one on each wingtip and the top of the rudder. They should self release after immersion in 5 feet of water and be buoyant. $1000 to install, $100 a year. Cheap insurance.

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#163

Post by wglb »

fnordfnordfnord wrote: post #161
wglb wrote: post #156

Earlier quoted context omitted.

From my comment ancestor to this thread: Keep in mind that over-the-horizon radio communication is subject to the vagaries of the ionosphere and is not totally reliable. Non-line-of-sight radio communications are short wave (well, also medium wave and long wave, but those modes require significant power). If ionospheric conditions are bad, as they are at many times of day (worse at night for some bands), at many time…

>So to put a number to your question "likely better than half the time". I'm not sure how you get from 'because communications between arbitrary point A and and arbitrary point B are sometimes impossible on band C' that "likely better than half the time" communication will be impossible on every useful band to any useful place.

Band outages are more often than not correlated.

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#164

Post by kb6kgx »

I presume that the “black box” is located somewhere in the plane that is likely quite inaccessible to the crew and/or terrorists that may wish to disable it. It’s a sealed box, and I would presume that the crew would not have the tools to open it and that it is unlikely to have a simple “on/off” switch with which to turn it off.

But… COULD it have been diaabled? Why have no “pings” been picked up as yet?

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#165

Post by kb6kgx »

I presume that the “black box” is located somewhere in the plane that is likely quite inaccessible to the crew and/or terrorists that may wish to disable it. It’s a sealed box, and I would presume that the crew would not have the tools to open it and that it is unlikely to have a simple “on/off” switch with which to turn it off.

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#166

Post by shirro »

I don't know if this is practical or not. Have two or more compartments on a plane filled with dozens of small highly reflective buoys. Each with some sort of radar reflector, either passive or active, that searchers could light up with radar and it would emit back a strong signal. In event of a breakup their container is designed to scatter them everywhere or in a more controlled situation the planes systems could release them. Ofcourse they will drift in the air and in the ocean currents but you could analyse then statistically along with knowledge of wind and ocean currents to at least narrow the search area in a situation like this one.

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#168

Post by Alphasite_ »

jarek wrote: post #77
MISTERSASB wrote: post #58

Great discussion. I now understand more about the objections to replacing a black box with satellite streaming data . The two major objections seem to be 1) a catastrophic event could bring external communications to an immediate end and 2) the high data density could make it impractical to link it all to a satellite. As to the first objection, any catastrophe would be preceded by the cause of the catastrophe. This i…

> it could be of great value to have instant access to events just prior. Why is it a significantly larger value than having access at worst two years later? No plane went down due to the same problem while they were looking for the AF 447 black box. > Anything that can be done to reduce the time needed to locate passengers who are injured or trying to survive on the ocean or in difficult conditions deserves a look,…

Well, for example if it was design issue they could pull all effected aircraft immediately, rate than waiting for the next one to crash over and and getting the blackbox then.

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#169

Post by jarek »

Alphasite_ wrote: post #168
jarek wrote: post #77

Earlier quoted context omitted.

> it could be of great value to have instant access to events just prior. Why is it a significantly larger value than having access at worst two years later? No plane went down due to the same problem while they were looking for the AF 447 black box. > Anything that can be done to reduce the time needed to locate passengers who are injured or trying to survive on the ocean or in difficult conditions deserves a look,…

Well, for example if it was design issue they could pull all effected aircraft immediately, rate than waiting for the next one to crash over and and getting the blackbox then.

In practice, that's just not an issue these days.

Most crashes are due to human error or complex system problems that often include already known issues rather than a single thing failing catastrophically. Airbus put out a maintenance bulletin about pitot tubes freezing before AF 447 crash, and cockpit/crew management, concentration and problem solving while startled, and computer mode confusion were all known. The most recent example of one solid hardware problem are the 787 batteries and thanks to QA systems we know they are problematic but, fingers crossed, so far they haven't gotten bad enough to kill people. If a 787 goes down you know this will be the first thing looked at even without instant access to logs.

A new airplane entering production with a flaw that will go unnoticed until it suddenly starts crashing planes en masse is just incredibly unlikely. On balance of probabilities, we're better off focusing on existing known problems rather than coming up with super high tech monitoring schemes.

Re: Malaysia Airlines flight MH370 makes it clear: we need to rethink black boxes

#170

Post by smsm42 »

yardie wrote: post #141
smsm42 wrote: post #139

Earlier quoted context omitted.

But do they really need to "operate" under these harsh conditions? They need to preserve the recorded data (which AFAIK with a suitable magnetic storage requires no processing power and no energy, just ability to stay mechanically together) and to do something to be found - like send GPS coordinates out on exceptional event and/or a loud radio ping that can be located by search teams after the crash. That shouldn't b…

A plane can be on fire and in flight simultaneously. If the compartment the blackbox is kept in is on fire or near the hotspot you don't want it cutting out too soon. Blackboxes are equipped with a sonic and radio location beacon. Because of the remote locations they have to work in battery life is measured in days and hours since they have to send out a fairly powerful signal using the weakest antenna configuration.…

>>> battery life is measured in days and hours since they have to send out a fairly powerful signal using the weakest antenna configuration.

They don't need to send it continuously, so I wonder why it is only hours. Sending a loud short ping once an hour shouldn't consume too much energy. Of course, I don't know enough about radio physics to know if it'd be enough, say, if it is 1km underwater - that may be a problem. Maybe supplement it with acoustic ping too?

GPS is not needed continuously too - it can record last reading, say, before high-g acceleration event and then let the GPS unit be destroyed, burned, starved of power or whatever happens to it. I.e. continuous GPS is needed only when everything is OK and the device is connected to the plane's powerplant - once it is disconnected, record last known GPS and shut down everything - we're in trouble, so the only task for it now is to scream loudly until it is found.

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