Malaysian Airlines MH370 contact lost

[HeavyMetallist]

@Recc:

We developed the RATS to track the model V22P acoustic transmitter [...] which is specified to transmit a 36-kHz “ping” at 165 dB once every 700–1100 ms. The pulse duration of the ping is 10 ms

You forgot to mention that the 700-1100ms pulse interval isn't a tolerance, it's a range; the pulse interval is varied to encode the depth of the transmitter. The chance of it being precisely, and consistently, 1s is therefore remote, and readily distinguished from an aviation ULB.

[Recc]

You forgot to mention that the 700-1100ms pulse interval isn't a tolerance, it's a range; the pulse interval is varied to encode the depth of the transmitter. The chance of it being precisely, and consistently, 1s is therefore remote, and readily distinguished from an aviation ULB.

True, but I wasn't meaning to suggest that it was this particular model; it was just an example of the kind of technology that was out there. The basic model (for example) comes with a factory set pulse interval and frequency (between 34 and 50kHz).

[thommo101]

@Rampstriker

"We developed the RATS to track the model V22P acoustic transmitter [...] which is specified to transmit a 36-kHz “ping” at 165 dB once every 700–1100 ms. The pulse duration of the ping is 10 ms"

Before people buy the hype from that article, let me remind you that these types of acoustic tracking tags are designed for SHORT TERM deployments on whales allowing for high resolution tracking with suitable distributed receivers.

For example the unit in the above paper lasted for 4 and a half hours attached to the whale.

These types of pingers are NOT deployed for long term detection.

Examples of pingers that ARE designed for long term (mentioned in @overthewing's post) are higher in frequency (62kHz), do not ping as regularly, and and rather low power (~145dB SL). These are used for shark tagging around Australia.

Now I'm not saying the signals detected by Ocean Shield are NOT from acoustic whale tags. All I am saying is it is HIGHLY IMPROBABLE that they originated from a whale tag.

[RationalKeith]

Isn't frequency and

My understanding from credible comments in fora like this is that the combination of frequency and modulation method is different for various uses, aviation recorder beacons are unique.

[Ian W]

Originally Posted by HeavyMetallist

If the audio was modulated with a code then that would have been very obvious when they analysed the signals.

As for uniquely coding aviation ULBs - there's not a lot of point since, unlike with tagged animals, in any given ocean in any given 30-day period it's hardly likely that there will be more than one pair of ULBs down there!

I think that the last few weeks since the ULB signal was found have defeated your argument. As the ULB has faded and the wreckage has not been found there are large numbers of people including the satellite experts down thread, that are claiming that the aircraft is in a totally different position and the ULB pings were some kind of artifact. Compared to the expense of the search coding the ULB with something sensible would have stopped all the fruitless discussion about 'the Northern route' and doppler shifts and aircraft in the Andamans or Diego Garcia. Just a simple coded ping equating to the MH370 airframe would do. Even better a depth indication added to that would be extremely useful to SAR and recovery operations. Judging by the comments on tags for underwater animals these capabilities are off the shelf items and can have a useful life of ten (10) years!! And EASA thinks that they are pushing it to ask for 90 days?

[overthewing]

The purpose of ULBs is to help locate the recorders once you've got within within a few kilometres of them, not to narrow down the crash site in the first place.

Perhaps this event is revealing that the original assumptions about ULBs need to be revised? Perhaps when the requirements were first specified, oceans were relatively quiet places, with very little alternative electronic noise to worry about?

[Ian W]

Originally Posted by HeavyMetallist

The fruitless blathering really doesn't matter - all that matters is what the real experts who are searching for this aircraft know, not how satisfied random individuals and self-appointed experts posting on the internet are. The purpose of ULBs is to help locate the recorders once you've got within within a few kilometres of them, not to narrow down the crash site in the first place. If you're got near enough to hear a ULB then it really doesn't matter if it's coded or not.

Well in this case the ULB was heard yet it did not allow anyone to locate the recorders then the ULB's died. So now the actual crash site is being questioned. Why not add a really simple low cost ID code to each pulse? It will cost pennies and resolve issues such as those being experienced now.

[oldoberon]

Guys 370 is either in the red yellow, green box or to the side of one of them

Imarsat data and methodolgy was peer reviewed by AAIB and others.

Whilst many impressive alternative calculations appear on the forum and other places, you can bet those responsible for the search read and check those suggestions/criticism to see if they do show there has been a miscalculation or oversight on their part, or a valuable idea to consider, they are neither daft or stubborn.

Unfortunately no "outsiders" gets the board's data so can't see the full picture that the board can. but that's the way the cookie crumbles with such investigations.

[Porker1]

@IanW

No doubt the transponders that have a potential battery life of 10 years are of a similar nature to those used on diving bells. Rather than "pinging" relentlessly from day one until exhausted, they save their power to reply to interrogative pings from searchers, allowing the SAR team the time to determine and arrive at the search area.

Having such reactive ULBs attached to the FDR & CVR seems like a good idea, but for (rare!) scenarios such as this one another transponder producing a lower frequency signal with a much greater range would also be damned useful. It wouldn't have to be associated with black boxes and could at least alert the searchers to the general location of the airframe.

[FlamantRose]

Considering that it would actually appear that nobody has the real slightest idea of the whereabouts of MS370 as all searches have shown negative results, I am hereby referring to ''SiriuslyCold's'' post # 135 dated 08 March at 09:56 on page # 7 that states :

I'm wondering why no one has remarked on FlightAware's ADS-B data further down the page, where it's picked up at 22.3598, 114.0461 by the receiver at VHSK?

Registre de suivi des vols ? MAS370 ? 07-03-2014 ? WMKK / KUL - ZBAA / PEK ? FlightAware

I don't recall seeing any further msg refering to that post but I may have overlooked or misread and stand therefore to be corrected.

When you look at the chart it starts off at 17:51 and the flt proceeds up to 18:12 showing acft at FL 37000 flying north east and then all lines below remain blank for the exception of, I guess, programmed flight path. It remains so until 20:49 when it re-appears at FL 39100 routing 24° until 20:51 when it disappears again for good.

Where does this information come from ? Could it belong to another acft ? If not what initiated that info ? Can someone find out by possibly enquiring Flight Aware ? There has to be something that re-activated the ADS-B Data (even if it is a bug).

[rampstriker]

Subwoofers on ULBs

As was mentioned somewhere way back lower frequency sounds require bigger speakers. A "subwoofer" pinger assembly would almost certainly not meet ULB ruggedness criteria due to the physics of scale. But a somewhat lower frequency could be within the realm of possibility.

[uqcodonn]

Ocean Shield

ABC News Australia:MH370: Ocean Shield returns to Malaysia Airlines flight search area after resupplying - ABC News (Australian Broadcasting Corporation)

Reporting that Ocean Shield is on its way back to the search area and still with Bluefin-21 (with software update).

The story cites Capt. Matthews:
"Concurrently there's a team in Canberra that includes ATSB, NTSB, Boeing and Inmarsat looking at the satellite data, just to take a fresh look, make sure they refine as much as they can the broader search area."

Captain Matthews says it is impossible to definitively say the signals detected last month were from a black box.

"It is certainly a man-made signal, but what it's from, I can't look at it and positively say 'hey that's an underwater locator beacon'," he said.

[framer]

Where does this information come from ? Could it belong to another acft ? If not what initiated that info ?

I imagine it has probably been explained earlier but I would also be interested in what generated the information. The aircraft that generated it was doing 511kts. MH370's ground speed showed 473kts at top of climb. The average of the two is 492kts. At that average ground speed it would take 2 hours 48mins between KL and VHSK, that data shows 3 hours after departure.
It would be nice if someone could explain why the data is not relevant or can be discounted for whatever reason.
Cheers.

[Squawk_ident]

About the supposedly MAS370 7th of March tracking on FA, neither the timeline or FL match the good values. The final cruising of the MAS370 was FL350 and ADS-B was lost at 17h21z. The data indicated are those of the MAS370/06MAR in local time but 07MAR UTC time. The relevant MAS370 was the one operating the day after on the 08MAR UTC/CET time.

[Sir Richard]

Squawk_ident

Please check your watch and time zones:

1721 UTC 07 March = 0121 Malaysian Time 08 March (UTC + 8)

My previous (removed) post alluded to this fact.

Please check the quoted MAS statement on page 1 of this thread

[poorjohn]

"They did seem very sure that they had located a ULB though, in which case, your original point would still stand"

correct. lets forget all handshakes and inmarsat - when you receive in the middle of the indian ocean where no other aircraft crashed short range stationary pings from a device that is confirmed to be a blackbox ULB which start to fade away just 30 days after mh 370 vanished - what else can it be than a malaysian boeing 777 directly unter your feet ?

this pings either never existed or were from another source OR bluefin is not able to fully scan the bottom because otherwise MH370 must have been found .

Pardon me if this has been discussed - I gave up reading this thread midway due to so much uninformed speculation - but iirc from the AF447 threads an acoustic wave can be bent as it passes through the interface between media of different density (e.g. layers of different temperature) and thus peak detection would occur when the receiver was not directly overhead the source.

[Heathrow Harry]

any wave (light,sound, earthquake) can be refracted at any interface (assuming it is not at exactly 90 degrees to the incident surface) where the physical properties differ sufficiently

Refraction - Wikipedia, the free encyclopedia

[underfire]

What amazes me is how this entire search effort has been run and has fallen apart.

Some common sense, and easily determined processes have been completely ignored.

As an example, with a pinger search, reverse the thought process using simple GPS navigation concepts.
The search vessel is a satellite, and the pinger is the aircraft that wants to know its location.
For GPS navigation, if you only see one sat, what do you get...nothing. with 2 sats, what do you get...distance. It takes at least 3 sats to get your position, correct?

So, with one search vessel listening to a pinger, what do you get...nothing

If you had 2 search vessels, they could coordinate their locations with the exact time they rec'd the ping. you would get distance, but along an infinite line.

If you had 3 search vessels collaborated, you would get the horizontal location. It is really that intuative.

One vessel, one UAV, whatever...seems relatively hopeless.

too bad the exact time of all of the different signals between all of the vessels could not be compared, if they happened all at the same time.

(it should be noted that transponder batteries can last a long time, beacause it responds to a signal. There are many biologics, such as dolphins and whales that it will respond to. Especially with dolphins, they will try to have a conversation with a transponder, wearing down the batteries pretty quickly)

[MG23]

Originally Posted by underfire

If you had 3 search vessels collaborated, you would get the horizontal location. It is really that intuative.

Yes, they just needed to magic up two more vessels equipped with towed pinger locators. Why didn't they think of that?

This search is really unprecedented. The aviation industry was never told it had to be able to find an aircraft that disappeared over the sea with six hours' fuel left and no active communication, otherwise they would have been ready to do so. We shouldn't be surprised that we're having a hard time finding it, but that there's any realistic chance of finding it.

If, for example, Inmarsat hadn't logged the time offsets in their handshakes, or hadn't realized they could be used to estimate the location, all we would know is that it flew on for six hours. That would leave us searching a circle a few thousand miles across, with pretty much no chance of ever finding the aircraft if it came down in the sea.

[underfire]

Yes, they just needed to magic up two more vessels equipped with towed pinger locators. Why didn't they think of that?

Why the attitude?

There were many, many vessels with TPL.

Just as the search pattern was noted before, 3 hours to turn rather than search a racetrack. Again, very intuative, and very common when searching.