Malaysian Airlines MH370 contact lost

[Machinbird]

Each of the transmissions on April 8 were intermittent and at a frequency of around 27 kHz—much lower than the 37.5 kHz frequency that beacons are designed to emit, and also lower than the 33.3 kHz frequency of other transmissions on April 5. "As far as frequency goes, between 33 kHz and 27 kHz is a pretty large jump," Cmdr. Lybrand said."

The degradation of supply voltage (such as when batteries become exhausted) is known to have effects on oscillation frequency of crystal oscillator circuits including oscillations in other modes.

The pingers are essentially variants of crystal oscillator circuits. Has anyone seen any data about actual pinger frequency performance as the batteries approach exhaustion? It would seem reasonable that the manufacturers would have run these tests already.

[mm43]

Prior to the current side-scan sonar search using the Bluefin-21 getting underway, the Ocean Shield spent some days towing the TPL equipment. While this was happening, HMS Echo moved into the same area when appropriate to undertake a comprehensive analysis of the water conductivity, temperature and depth using a CTD probe to measure those variables and determine the affects that would be encountered by the ULB acoustic pings on their travel to the surface.

They also used an Expendable Bathythermograph to further check the accuracy of temperature and depth recordings, while their HiPAP (High Precision Acoustic Positioning) sonar was being used outside its normal operating parameters to listen for the aircraft transponder.

I doubt that chucking another ULB into the water is going to tell them anything of relevance they don't already know. There is adequate evidence also available from the initial recordings of the ULB pings to confirm that their acoustic frequency was decreasing at a rate comparable with that of a similar battery of its age and operating time combined with the local water temperature.

A Dukane spokesperson has previously acknowledged that the 33.331kHz pings were what could be expected. The oscillator is not Xtal controlled, being a resistive/capacitive oscillator with the low Q transducer forming part of the circuit.

[Tas62]

JACC Update

Todays JACC update: Update on MH370 Search

[Machinbird]

A Dukane spokesperson has previously acknowledged that the 33.331kHz pings were what could be expected. The oscillator is not Xtal controlled, being a resistive/capacitive oscillator with the low Q transducer forming part of the circuit.

Hi mm43
I suspect that the transducer will operate in a manner similar to a quartz crystal oscillator, just at much lower frequencies due to its much larger dimensions. Once internal amplifiers begin to operate non-linearly due to the low voltage, it might be possible to stimulate other oscillatory modes in the transducer. This would account for significant deviation from the base frequency. Just theorizing of course.

Detection of a pinger while it is operating in a low voltage manner would probably indicate you were almost on top of it, thus the question of what happens at very low voltage is not entirely irrelevant.

[mm43]

@Machinbird,

Your deduction is on the ball. My only consideration would be if acoustic ducting was taking place, which may have been the case as I believe that the TPL was only at 250~300m depth when the #1 Ping detection was made, and the vessel was moving very slowly over the detection period.

There is some Doppler shift associated with the ping repetition period, and I believe that it is greater than the horizontal component of the vessel's speed. The residual looks as if it is due to the frequency decay on account of the continuing lowering of the battery voltage.

In summary, the current search may not turn up anything due to water depth increasing quite rapidly to the north, and possibly beyond a modified max pressure/depth that the Bluefin-21 can confidently do.

[toaddy]

I've been reading ULB manuals and patents I'm still confused about the ducting of acoustics in the water. I understand that temperature and salinity levels, water surfaces, ocean bottoms, etc. can cause the sound to be refracted, or reflected or whatever; and I keep reading that water will attenuate the ULB pings at roughly 5 to 7 dB per km, depending on depth, salinity, temperature, etc.. I'm guessing that the ducting waterways we hear about don't consist of 'magic' water so the pings still get attenuated at the same 5 to 7 dB per km, just perhaps bounced in odd directions.

Is that about right ? If so, then the source has to be pretty close to the detection areas. Even if the sound is being bounced around in crazy directions, it's still getting attenuated at a known rate as it moves. I can see if the ULB fell into a parabolic shaped canyon and the canyon walls were acting as a focusing (antenna)transducer, maybe the range could be a little further but it still seems like it has to be in the right neighborhood. Maybe they haven't found the haystack yet but they very likely are on the correct farm.

Here's an old test the FAA did back in 1968 when they dumped a fuselage in the water off the florida keys in 200 feet of water to see if a fuselage encapsulated ULB (inside the pressure bulkhead) and another test (outside the pressure bulkhead) could be detected from the surface. http://www.fire.tc.faa.gov/pdf/na68-7.pdf They were able to detect it to about 3000 yards at the surface (where the noise is worse).

And here's a fascinating patent, that mentions that the ULB's for KAL Flight 007 that crashed in '83 in the sea of Japan were never found and it mentions..."Recovery of the KAL 007 flight recorders may have been severely hampered by intentional acoustic jamming." It's a patent by Sandia Research for ULB's that are about the same size as the current version but is lower powered, with longer range, undetectable (signal is weak and below the noise floor) unless the correct code is known (spread spectrum), and can be uniquely identifyable to a specific aircraft/torpedo/etc.. Apparently it was developed for the military to use on experimental underwater toys in case they got lost and they wanted to be able to find them first before another nationality could find it. The ULB's would require only minor changes but the ping receivers would need some extra signal processing abilities. Patent US4951263 - Spread spectrum underwater location beacon system - Google Patents

[mm43]

I've been reading ULB manuals and patents I'm still confused about the ducting of acoustics in the water. I understand that temperature and salinity levels, water surfaces, ocean bottoms, etc. can cause the sound to be refracted, or reflected or whatever; and I keep reading that water will attenuate the ULB pings at roughly 5 to 7 dB per km, depending on depth, salinity, temperature, etc..

Where that attenuation component gets dramatically reduced, is when the acoustic signal gets trapped within a temperature/salinity incline. The spherical component of its radiation is focused within this trap with a far larger component of the radiation able to continue the journey to the point of reception/detection.

[RTD1]

Something is not right here

These folks are truly experts and immensely experienced. They expressed no doubts as to the origin of the Pings, which occurred where, obviously, they expected them to occur. Now they all believe the Pings were not from 370 and that is the reason for not releasing the recordings. I'm not much into conspiracy theories but something very odd has happened here.

Pretty sure nothing in nature makes 37.5 kHz pulses lasting 10 ms on 1 second intervals. Also pretty sure no other planes had crashed there in the past month. That means someone threw a pinger into the water.

For all those people who were uncomfortable with the idea that a group of Chinese on a rubber raft with a fish finder on a pole could have found the signal, you may have your answer now.

[Left Luggage]

Pinger Doubts?

Can anyone point me to an official source expressing doubt over the validity of the pings recorded by Ocean Shield in early April - and I don't mean Yahoo news or the Daily Mail.

A week or so ago there were doubts being expressed here about the April 8th pings but I couldn't see a source for those doubts. Now it seems there's doubts being expressed about the April 5th pings and I still can't see an official source for these doubts.

If the Ocean Shield pings are discredited then it means we're backing looking for the haystack!

I do note however that today's JACC update that they say "Over the next week, Bluefin-21 will search the remaining areas in the vicinity of the acoustic signals detected in early April ..." Which suggests to me the offical SAR isn't completely discrediting the pings.

[Fairsky]

ACARS ping arcs

I’m becoming more sceptical of the reliability of the ping arcs and the one piece of information which would give me confidence is the calculated arc of the 0107L ACARS transmission compared to the known ADSB track.

My understanding is that the subsequent transmissions were handshake pings only and yet these are the only transmissions from which I’ve seen published ping arcs.
An arc from the 0107 transmission would verify the calculation method of the later arcs IF it perfectly intersected the known ADSB track at that time.

So my question is; has anybody seen that verification ?
If so, could you provide a link to a reliable source.

[Ornis]

MAS didn't subscribe to the satellite service, ACARS was VHF only.

[HeliBot]

RE: What's Tony Abbott going to be able to tell them?

"This is a problem that was caused by the previous Labour government, however we are stopping the boats. Also, this is a responsible budget that Australia had to have (what's an economist?)."

[MG23]

Originally Posted by DrPhillipa

Isn't it about time that MAS actually admitted this, rather than negligently allowing people to assume otherwise - thus supporting erroneous implications about the "sudden loss" of ACARS over SATCOM?

I've wondered where that rumour came from, too. I thought it was specifically the RR engine monitoring ACARS messages which wouldn't go over SATCOM?

[DrPhillipa]

MG23: Wasn't it the NYT right at the beginning that was rumouring that RR had received status reports for hours after MH370 "disappeared". RR, and I think Boeing, simply denied this if I recall. Then a couple of days later the Inmarsat handshake data came out. I suspect maybe that NYT asked someone about continued SATCOM contact and assumed that MAS had subscribed to the data service available under Classic Aero H. As I understood it MAS did not want to pay the bandwidth/traffic fees for the RR/Boeing/EICAS ACARS data which for example AF447 was running.

These sort of details should have been in the provisional report as I see it.

Did anyone try to contact them on the Sat Phone that we know of? Wouldn't such a call, even if unsuccessful, have left traces in Inmarsat logs?

[WillowRun 6-3]

Civil Aeronautics and Air Defence

Kudos to Propduffer for post on 20 May (20:18) - and not only because it bears repeating that indeed, the disappearance of a commercial airliner with all its passengers is an event of global interest and one in which many posters here hold unquestionably legitimate interests (despite some posters who may not).

On the subject of what actions the Malaysian military took, and what actions it failed to take: it appears reasonably clear that their inaction was far from optimum, and could have constituted a deviation from SOP....but this leads to a question. Is there part of any of the several ICAO Annexes which speaks to what steps a signatory nation's air defense authorities are "expected"* to take under circumstances involving loss of contact? ("Expected" because - as has been noted earlier on-thread, ICAO issues standards, not quite the same as "law".). Presumably the answer is a short and simple one, akin to "no of course not - no military is subject to the regulatory system for civil aviation; they'd never accept such a subordination."

But consider: let's just assume that having a single official holding charge over both civil aviation and a nation's military is a textbook exemplar of conflict of interest. Here, the informational deficits, and deteriorating official credibility, suffice to make the point (and for any doubters, the "shoot down" scenario is inherently intractable, isn't it?). So a reform could well be to require signatories to the ICAO regulatory architecture to separate the civil aviation authority from the country's national command authority. Where would this fit in the existing ICAO architecture? Or would it be an entirely new subject matter?

[ATC Watcher]

Where would this fit in the existing ICAO architecture?

Nowhere because ICAO is purely civil, and does not, by its founding convention, extend its standards and recommeded practices to military aviation.
Each State is sovereign in his own national military procedures.
The only execption are the rules of the air to intercept civil aircraft ( how to postion yourself, and how to respond, etc..)

There are no internationally agreed "rules" on wether or not to intecept an aircraft ,each State has its own regulations.

[WillowRun 6-3]

Air Policing

Clearly ICAO's current architecture (both in the concrete sense of existing agreements, standards and practices, as well as in the conceptual sense) does not appear to reach air policing in a comprehensive, or even broad, way. But consider the explanations of the informational outputs one could expect from a scramble by Malaysia - as detailed by Blake777 (20 May, 4:28), and of the procedural aspects as set out by RetiredF4 (6:32). I'll forecast that the investigatory report which ultimately is produced not only will consider this topic, but also will have as a primary context for discussion of what the Malaysians failed even to try to do, the fact that gaps in air policing capabilities generally, and here exacerbated by the existence of a "two-hats" official, have arrived at the top of the agenda (for improvement and reform of worldwide civil aviation regulatory structures). If this seems overheated, or unduly speculative, request a re-reading of the quite plausible linkage between a gap in air policing, and a hijack or similar takeover, as sketched by the above-referenced post written by RetiredF4.

[portmanteau]

willow run. there is an interest but not a conflict of interest. every country has at least one official who is in charge of both civil and military aviation, he' s called the prime minister, president or similar title ie the head honcho. the fact that he/she may have heads of departments under them with similar dual roles due perhaps purely for reasons of size, is not significant. military aviation can't do just what it likes (including refusing to disclose anything) any more than any other department of government. if govt orders the military to go up and have a look at a potential intruder or search for a lost civilian aircraft, then they better jump to it or else.

[WillowRun 6-3]

Those are very valid points, Portmanteau - but at the same time they do not account for all of the subject matter in discussion in this corner of the thread. Yes obviously there is a highest-ranking authority in a given sovereign nation .... but it does not necessarily follow that military commanders will be subservient to and compliant with lawfully constituted sovereign authority. For brevity, I'll simply cite "military coup d'état". And, in some countries even without power concentrated in its military, the civil authority may be a figurehead more than a real decision-maker.
More generally, is it not the case that where a "standard" air defence rule of engagement would activate a scramble to ident, this action does not require the okay of the leader of the national government? In other words, the existence of a head of a country's national government does not either mitigate, or erase, the relevance of the larger question - how should the worldwide civil aeronautics regulatory system improve its interaction with air defence authorities (where such defences exist)? - or the more particular one - should signatories to such worldwide system be strongly encouraged not to give both the defence and civil aviation portfolios to the same minister?

[Ian W]

Air Policing

@ Willow Run.

It has to be emphasized that the Malaysian ATC followed the book pretty well. They were not responsible for the aircraft which had been handed off and accepted by Ho Chi Minh center. Aircraft are not 'overdue' until 30 minutes after their expected arrival time that was several hours later. So it was literally someone-else's-problem. How could they 'scramble the military' when they did not know where the aircraft was and probably suspected it was NORDO in Vietnamese airspace still proceeding toward Beijing?

The Malaysian military would have seen a comair turn back almost certainly still flagged as a Malaysian aircraft. It could be argued that the lack of secondary would have caused interest, but the military had not been contacted by civil saying they had lost an aircraft.

This is what happens when it is peacetime and no threats are apparent. But nobody broke any rules nor is there any real reason for creating any new laws or rules. Automated tracking of aircraft would be good, is feasible using existing equipage and protocols; that is where the concentration should be.