Malaysian Airlines MH370 contact lost
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37.5khz Meant to Locate CVR & FDR Within a Crash Site. Not for Finding a Crash Site.
"bobcat4: Why use 37kHz when lower frequencies travel longer in water? I'm just curious."
The main reason is the ULB was never meant for finding a crash site. It was meant to find the black boxes within a crash site, and a higher frequency is easier to pinpoint, and less likely to be confused with lower frequency noises from ships and other equipment. Also, it uses less battery power than lower frequencies.
Back when 37.5khz was established as the frequency in ULB's, people figured if a crash was so far out in the ocean, where you didn't know where it went down, it would be too deep to get to anyway. Now that the use of deep diving robot vehicles is not uncommon, maybe it would be a good idea to add an 11khz ULB to locate a crash site, since 11khz travels farther through water than 37.5khz, and common sonar can hear 11khz, so you wouldn't need special equipment.
The main reason is the ULB was never meant for finding a crash site. It was meant to find the black boxes within a crash site, and a higher frequency is easier to pinpoint, and less likely to be confused with lower frequency noises from ships and other equipment. Also, it uses less battery power than lower frequencies.
Back when 37.5khz was established as the frequency in ULB's, people figured if a crash was so far out in the ocean, where you didn't know where it went down, it would be too deep to get to anyway. Now that the use of deep diving robot vehicles is not uncommon, maybe it would be a good idea to add an 11khz ULB to locate a crash site, since 11khz travels farther through water than 37.5khz, and common sonar can hear 11khz, so you wouldn't need special equipment.
Last edited by Coagie; 29th Mar 2014 at 17:05. Reason: Punctuation
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Five ways to make sure we never lose a plane again
1. Flight tracking over the oceans is already possible and it's cheap
2. Make accident conditions trigger black box data bursts
... more at New Scientist
Five ways to make sure we never lose a plane again - tech - 28 March 2014 - New Scientist
2. Make accident conditions trigger black box data bursts
... more at New Scientist
Five ways to make sure we never lose a plane again - tech - 28 March 2014 - New Scientist
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"bobcat4: Why use 37kHz when lower frequencies travel longer in water? I'm just curious."
Keeping Danny in Sandwiches
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TwoOneFour.
How did you derive those co-ordinates?
Plotting those points into Google Earth the eastern boundary line follows the direct track from IGREX to YWKS, the western boundary line goes very close to the direct track from IGREX to SPOLE.
How did you derive those co-ordinates?
Plotting those points into Google Earth the eastern boundary line follows the direct track from IGREX to YWKS, the western boundary line goes very close to the direct track from IGREX to SPOLE.
Everyday Flotsam or MH370 Debris
AMSA has rightly pointed out that any retrieved object has to be positively identified as coming from MH370.
This piece of ocean receives very little close scrutiny. There seem to be a number of gyres where flotsam goes round and round. Any MH370 debris may be a very small proportion of what has already been there for quite a long time.
This piece of ocean receives very little close scrutiny. There seem to be a number of gyres where flotsam goes round and round. Any MH370 debris may be a very small proportion of what has already been there for quite a long time.
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I am sure the powers that be will have gone through every medical record, through every bit of paperwork, computer entries, interviews with work colleagues, even down to drinking/drug habits etc.
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twentyman
Because they are not using the same cameras as do the satellites or spy planes. Most pictures seem to be taken using a handheld camera, some are of a picture on a computer screen.
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Speed of Sound wrote:
I found out that the main reason is the size of the beacon. I'm not sure about the power consumption.
According to https://fenix.tecnico.ulisboa.pt/dow...651/resumo.pdf
As well as what Coagie said it takes proportionately more power to generate and transmit an 11KHz signal than it does a 37.5KHz one, therefore for a given amount of power the 11KHz will be sustained for less total time than the higher one.
According to https://fenix.tecnico.ulisboa.pt/dow...651/resumo.pdf
Decreasing the ULB transmitted signal’s frequency. The attenuation losses induced by the Underwater Acoustic Channel (UAC) are highly dependent on frequency, and increase proportionally to its cube. Hence, reducing the current 37.5 kHz to a reasonable 10 kHz has the potential to greatly enhance the maximum depth and range for which the ULB signal can be detected. The downside of this solution is that the physical size of the beacon would have to increase
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Facts. We have science and technology because Man didn't wait for facts. He guessed and he imagined and he tried and he demonstrated.
It's perfectly obvious that the chances this was not a carefully planned act of vengeance is somewhat less than my winning Lotto. Of course someone does win Lotto, so it's not impossible it was the wrong kind of fire at the wrong place at the wrong time.
The fact is, the Universe is based on probabilities, and so is our knowledge of it; how we make sense of it.
It's perfectly obvious that the chances this was not a carefully planned act of vengeance is somewhat less than my winning Lotto. Of course someone does win Lotto, so it's not impossible it was the wrong kind of fire at the wrong place at the wrong time.
The fact is, the Universe is based on probabilities, and so is our knowledge of it; how we make sense of it.
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The Australian-led search is looking west of Perth because there is a high probability that is where the aircraft crashed. It might have gone north but the science points south. Unfortunately there isn't enough information to pinpoint a small area, so there's a big element of luck. Never want to underplay the part of luck in life.
If there's bits floating, the Orion crews will find it. These guys want to show their mettle.
If there's bits floating, the Orion crews will find it. These guys want to show their mettle.
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New and as yet unconsidered theory - pilot as hero
Hi
One fact seems indisputable amid all the speculation, that MH370 executed an extreme turn to the left. The notion that the plane then flew south to the Indian Ocean also now seems to be accepted as fact.
Question: is there anything in the nature of the turn to the left and its subsequent route which gives us a clue as to the nature of the events on board. If the desire was to fly to an unknown point in the Indian Ocean (or indeed any location), was this the only way to execute such a desire. Was the route to a point off Perth the only route available> If not, why this particular manoeuvre and why this particular route?
Theory: Is it possible to speculate that the plane was hijacked, and the pilot instructed to fly to a destination such that it became clear that a 9/11-type event was planned? The pilot was instructed to fly to an altitude to incapacitate the passengers, with hijackers and pilot provided with sufficient oxygen.
Could the pilot, in an act of heroism, have set autopilot to fly the plane to a harmless destination in such a way that it could not be reprogrammed, likely sacrificing himself in so doing as hijackers would have become aware of this at some point. The plane then flew its course, unable to divert, with hijackers alive onboard until the moment of crash.
One fact seems indisputable amid all the speculation, that MH370 executed an extreme turn to the left. The notion that the plane then flew south to the Indian Ocean also now seems to be accepted as fact.
Question: is there anything in the nature of the turn to the left and its subsequent route which gives us a clue as to the nature of the events on board. If the desire was to fly to an unknown point in the Indian Ocean (or indeed any location), was this the only way to execute such a desire. Was the route to a point off Perth the only route available> If not, why this particular manoeuvre and why this particular route?
Theory: Is it possible to speculate that the plane was hijacked, and the pilot instructed to fly to a destination such that it became clear that a 9/11-type event was planned? The pilot was instructed to fly to an altitude to incapacitate the passengers, with hijackers and pilot provided with sufficient oxygen.
Could the pilot, in an act of heroism, have set autopilot to fly the plane to a harmless destination in such a way that it could not be reprogrammed, likely sacrificing himself in so doing as hijackers would have become aware of this at some point. The plane then flew its course, unable to divert, with hijackers alive onboard until the moment of crash.
There shouldn't be a reward for the people (not necessarily the technical team - it could be the Australian cabinet office) who set the zone for the wild goose chase that took place pre-Friday. Just an invoice for all the wear and tear, jet fuel, lost sleep, potential risk to crew and needless gigabytes of satellite imaging.
Of course, if the wreckage if found at a given lat/lon then all the armchair sleuths will say "why didn't you search there first?" but they will only say that after the event. :-(
And yes, the Australian government *ARE* going to get the bill for all the wear and tear, jet fuel, etc...
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The search area roughly corresponds to the area of the Diamantina Trench, which is up to 25000 feet deep. What are the chances of hearing the black box signal, or even being able to retrieve it, if it is down at those depths?
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Flight MH370: Searchers follow NZ lead - National - NZ Herald News
New Zealand Joint Forces head Air Vice-Marshal Kevin Short said the Kiwi searchers had been heartened after spotting 11 objects about 1600km west of Perth on Friday.
"Those objects turned out to be rectangular in shape, nothing bigger than 1 metre, some of them down to half a metre in size,"
"Those objects turned out to be rectangular in shape, nothing bigger than 1 metre, some of them down to half a metre in size,"
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Originally Posted by twentyman
Spy planes and satellites are said to be able to read a numberplate from a great height. Why are all the pix of probable wreckage such poor definition?
No satellite can read a license plate, even a military one. The distortion caused by the atmosphere alone would make it almost impossible.
But regarding the definition of the images so far released and their quality, it's easy to explain why they appear to have such a low definition.
You have to think of a satellite as a SLR camera... You either "zoom in" and cover a small area, and if you do so you're able to better identify anything that's inside that area, or you "zoom out" and cover a wider one, but of course if that's done it's harder to identify individual pieces or wreckage or so.
As no one really knows where the wreckage is, they have to cover a wider area hoping to find something resembling what they want to find. If they "zoom out" they'll cover more area and have more to work with, but they'll have to magnify and try to extrapolate anything they find.
Regards.
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What are the chances of hearing the black box signal, or even being able to retrieve it, if it is down at those depths?
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So because they have found no evidence of any dodgy behaviour they are not looking hard enough?
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IMHO money should be spent on the decades-old detachable ELTs rather than lower frequency pingers on the FDR if you can only do one thing. We are all looking something going BEEP-BEEP with our ears in an area nearly the size of Australia right now. The 406 MHz signal wouldn't find the needle, but it would find the haystack 