Dillboy asked in 7743 "I'm wondering how long it will be before it is announced that the South China sea is to be revisited."



Not before somebody realises that the sat pings are a distraction.

What are the odds of the longest ever suicide/terrorist/unmanned autopilot flight also being solved by the first and novel use of technology that was never designed for the purpose?

True and best comment on situation re search. Australian Commander 'We are not searching for a needle in a haystack. We are searching for the haystack'.

I think he means on the ground-station. This would work if the satellite just very stupidly relays the signal in its raw form somehow and doesn't interpret/regenerate it before. I'm a bit hazy in this area, but I know its possible to do with wavelenghts in fibre so RF should be amenable to something similar. And yes, I would not be (very) surprised if the ground-station actually does some full sampling of the IF frequency, and maybe even saves it for later. Extremely valuable for finding faults etc.

If you didnt know there are SDR USB-dongles that can do ~3Mhz bandwidth full sampling costing ~10$. That a satellit ground-station is capable of something similar is not weird.

When UnreliableSource said
he was clearly thinking of a recording at IF. The signal could well be reduced to a few key parameters, and even transmitting it raw would have take bandwidth numerically less than the IF.

"Necessity is the mother of invention."

Not sure if you bothered to read the piece on how INMARSAT applied their knowledge of their own systems to the science of radio waves and satellites to come up with estimates of the aircraft's position at various points in time.

Had other means been successful, they'd not have had to figure this out on the fly. As someone pointed out in that article, they " ... did about a year's worth of research less than two weeks."

That may be a slight overstatement, but it indicates how many man hours they applied to the problem to try and find a solution. During the first two days of the search, a lot of observers in the PPRuNe threads opined that they weren't finding any wreckage due to looking in the wrong place. That "wrong place" was the South China Sea.


Indeed. The haystack (or the first bits of straw from the whole haystack) are apparently being blown about by wind and wave.

Regarding the marker buoys dropped from fixed wing aircraft over debris in the SAR zone, can anyone advise how many days these devices are trackable for?

If we assume Inmarsat could have digested more data from MH370, would it not be prudent for ICAO to recommend to its members to find means to ensure such data will be transmitted in any failure or deliberate disconnect scenario?

Possible INMARSAT rf processing
 

I am not knowledgeable about the rf front end for the INMARSAT, but I am knowledgeable about AEHF and a few other communication satellites, and I would hypothesize they are similar. The comms between the satellite and the ground terminals (in this case, the aircraft terminal node controller (TNC)) use a form of PSK. All of the baseband and "IF" processing is done synchronously using digital processors, so there are digital to analog (D/A) converters prior to the upconverters and A/D's immediately following the downconverters. I don't know what the state of technology is today, but the converters may be sampling on the order of 400 MSPS to 1GSPS. For the receiver, the first digital process which is performed following the A/D is a fast fourier transform to channelize the data. This is then followed by a phase lock loop (PLL), which removes the doppler. By simply logging this phase correction used in the PLL (simply a number indicating radians per sample period) and sending it in the downlink to the INMARSAT earth station in Australia, INMARSAT would be able to reconstruct the doppler. This may be normal payload telemetry.

Fox News Channel's Bill O'Reilly called this accident correctly one week prior to the Malaysian Prime Minister's official announcement yesterday. O'Reilly said the plane was at the bottom of the Indian Ocean. You might not like his political views, but he nailed it-- unlike countless armchair experts in our profession.

Good to know they found it stefan

@nupogodi
 

There is a world of difference between being technically possible and realistically achivable hence my rather tongue in cheek comment about not coming to a PC World near you anytime soon. :)

Without wishing to don a tin foil hat (the world must be running short of tinfoil by now if this thread is anything to go by :)), consider this. The DSS sanitisation processes for hard disks requires the devices to be either degaussed (complete magnetic wipe to the point the drive becomes effectively unusable) or destroyed. One wipe cleans the drive but does not sanitise the drive which is interesting if NIST insist this recovery is impossible and one wipe sufficient... suggests to me that not everyone is buying into that being an absolute fact :oh: ;)

Although, even if you did get a mapping of the magnetic patterns, you are a long long way from reconstructing that to meaningful data. While it may be possible, the reality is that its very unlikely anyone actually will do this. In my experience the biggest things to worry about in computer forensic examinations are encryption and dealing with what you do find and making sure you do interpret that properly.

@Coastalpilot:
I did read this on CNN about their examination of the data:
Indications files deleted closer to final Malaysian Airline flight - CNN.com

The article suggests that on the 22nd the FBI examiners were just days into the examination of what they call a large volume of data. Depending on how much data they have, it can take a while to investigate all of it. It is not uncommon for forensic investigations to take weeks if there is a considerable amount of data so no response so far is not really conclusive of anything and examiners will generally want to examine in full before drawing any conclusions.

What I would be prioritising is retrieving deleted files and seeing if I could run those files in the simulator. This does also assume nothings encrypted and password protected... if there are passwords/encryption, then this data could take many months to restore and examine.

Interestingly there is a suggestion that the Malaysians may have messed up this part of the investigation. Firstly, they waited 6 days before searching the pilots home which would have allowed someone time to amend data on that. While they have strict laws on probable cause, the time delay would be of concern about tampering.

Also there seems to be some question about how they searched and seized - the whole CSI/Hollywood scenario of walk in, switch computer on, start typing on the keyboard looking for things springs to mind. If someone has hinted to CNN that they have concerns that the evidence wasnt secured immediately there will be concerns about the integrity of the evidence and that not securing it could have altered, deleted or added data which taints the whole process and casts doubt on any results they find.

What becomes more confusing is that 3 days ago when CNN were stating FBI experts were just days into the examination, this was stating with certainty there was no evidence on the computers:
Malaysia Airlines flight: investigators find nothing suspicious in pilot's flight simulator

The question then becomes the sources of these - is one based on an examination by Malaysian forensic examiners or from the FBI? Even this becomes a mess to determine reliable sources. It would seem rather odd for the Malaysian examiners to state that there was nothing suspicious if they hadnt examined all the data and then send the drive off to the FBI for retrieval of the deleted data. But I doubt the FBI would issue such a conclusive statement this early on in the examination if they havent examined all the data yet. :confused:

Has the full cargo manifest been disclosed as yet?

Good news from the Telegraph that the search is resuming today after yesterday's bad weather put it on hold.

"The search for wreckage of crashed Flight MH370 has resumed after the weather improved, with Chinese ships and Korean planes joining the hunt over a vast stretch of the Indian Ocean.
Gale force winds, rain and big waves prevented any sorties being flown on Tuesday but 12 aircraft will be in the air on Wednesday while Australia's HMAS Success plans to conduct a surface sweep of an area where two objects were spotted this week.
China's polar supply ship Xue Long was also due in the area, with other Chinese vessels on their way, as the search intensifies for the Malaysian Airlines jet that crashed into the sea after vanishing on March 8 with 239 passengers on board.
"Today's search is split into three areas within the same proximity covering a cumulative 80,000 square kilometres," said the Australian Maritime Safety Authority, which is coordinating the search.
"AMSA has tasked a total of 12 aircraft today to search for possible objects in the search area.""

@RichmanJoe

:) TNC, PSK, IF, DA/AD....

I am sure good old RF principles will pinpoint this aircraft yet.
If one of the victims had Android APRS via cell/sat phone (Thuraya) on board, he would be a hero...
I hope the APRS guys at least had a good look at Google Maps APRS of 08 March for just such an eventuality.
I call on all Radio Amateurs to have this very easy free APRS capability in their pockets when they travel internationally....
While we are waiting on the airline industry to play GPS tracking catchup...

KC9SGV

"Fox News Channel's Bill O'Reilly called this accident correctly one week prior..."

People who make definite statements without sufficient data are either not very clear thinkers or they are demagogues who want to be able to point back later and say, "See, I was right" (or have their followers do so for them).

While factually true, it's not relevant to what will have been discovered by now.

In my day-job I'm a cyber-forensic analyst. The very first thing I'd do on that drive is a run a timeliner - a program that extracts file events from the life of the drive. That is accesses, deletions, creations, moves etc. Timelining is by file-system nature incomplete but usually accurate. Luckily deletion events tend to hang around and also luckily, ensembles of events can give a pretty good picture of what happened even if many individual events are missing.

Timeliners can be run in minutes.

The investigators will already know with a high degree of certainty the macro events that happened on the drives over the past weeks and months. For instance installation or deletion of packages and system updates and when programs were last used. They will also have been able to recover most of the recently deleted files and fragments of files deleted some time ago (months to years).

They will have a full record of internet activity including web sites visited, search terms used. They will even have 'image' snapshots of many of the pages visited.

One thing that makes it more difficult is use of a secure deletion program. The actual content of files will be gone, but many of the file events will remain. Secure deletion would be a serious red-flag for investigators.

In conclusion. They already know everything they need to know / can know about the data.

Anyone know how many Vessels are now at the search areas ? seems thus far to have been a lack of vessels...with objects being sighted but so far unable to have been picked up.....any heli's available ?

ICAO Annex 12 - Initial Response
 

SunnySA
Quote:
Wouldn't the initial SAR actions rest with Vietnamese ATC?


Yes, sort of, but the point I was trying to make was that the Malaysian authorities did not initiate timely action (i.e. within 30 mins. of loosing transponder/radar/radio contact) to coordinate an S&R effort until it was basically too late; then, yes, the Vietnamese ATC would be the first to be contacted for assistance, followed by Thailand or whoever it was whose radar tracked MH340 turning around.

Still very early days in this investigation and at this stage we have no idea if the cause will ever finally be established beyond doubt.

One current line of thought is the pilot suicide one. I sincerely hope this does not prove to be the case. We already see some aviation authorities twitching at this likelihood - the DGCA in India is reported as looking at introducing psychometric testing for pilots as a result of MH370 even before the cause is declared (or even known):-

[URL="http://www.business-standard.com/article/companies/dgca-looking-at-mandatory-psychometric-tests-for-pilots-in-india-114032500763_1.html"]

I believe the DMT (Defence Mechanism Test) has been used by the Swedish military; it is felt that this eliminates individuals who are not up to the task before money gets spent on training them. Other slightly authoritarian countries possibly also test in this way. Yet overall I think that most informed opinion would query the value of any similar tests for commercial pilots simply on the basis of their validity. Many false positives would almost certainly result; indeed it would perhaps be that results needed to err on that side. This would simply debar many otherwise suitable individuals from the profession for very questionable reasons, at any stage of their career. We all can see that making flight crew pass through airport security and have, say, a jar of aftershave or a leatherman removed from their bag would go nowhere near preventing a pilot bent on destroying his/her aircraft; psychological evaluations would be equally futile. How often would they be undertaken - after all, a person's mental state of health can be very changeable over time. I would argue that peer concern/CRM/good open company management culture is a far more effective defence against this sort of act. That said, no doubt certain commercial organisations would see a good business opportunity in providing such services, aviation being perceived as a cash cow, and may well start pushing for this as well as some more nervous regulators wishing to demonstrate their grasp of the situation.

A professional pilot, military or commercial, goes through much rigorous selection and evaluation to get their licence and they then have continuous assessment of their ability and competency for the rest of their careers. No other profession comes close to being regularly and repeatedly assessed in such a fashion. That as final arbiters of safety of their aircraft they are made to endure humiliating "security" checks is bad enough; there is no need for this further knee-jerk reaction to what may or may not have happened in this instance.

Latest charts are extremely interesting, but they don't quite add up to me.

I actually sat down and tried to derive Doppler offsets by hand.

* The range of values in the chart is not right for 1.6 GHz - they should be much larger.
* It looks like we're looking at absolute values, not raw frequency shifts. The peak at 18:25 UTC corresponds to the time when the aircraft was flying directly westwards, towards the satellite. At 00:11, it was flying away from the satellite. These two points should have opposite signs of Doppler shift.
* The difference between "predicted north track" and "predicted south track" is WAY too large to explain by nonzero satellite orbit inclination or eccentricity. Satellite has inclination of 1.7 degrees, apogee of 35816 km and perigee of 35769 km. That's maximum speed of ~175 knots perpendicular to Earth-satellite axis in the north-south direction, and something negligible like 4 knots along the axis. Perpendicular component enters with a factor of at most ~0.11. Its absolute contribution is largest at the end of the track, when the satellite is contributing 20 knots and the aircraft is flying away from the satellite at the speed of 230 knots (total speed 450 kts, projecting on the aircraft-satellite axis leaves 230.) During the period up to ~21:00, when the aircraft is still near the equator, the effect of satellite inclination should be very small. Anyone is welcome to repeat these calculations.

Ultimately, I don't think that the chart is comparing the south track towards south Indian Ocean against its mirror image. In fact, a good fit for the "north track" would be the route that goes to Straits of Malacca and then turns and heads for Beijing. That's the only way to arrive at a high Doppler shift early on, at 20:00 to 21:00 (because the aircraft is to the east of the satellite and moving northeast, while the satellite is moving south). They could also be comparing against a track that heads northeast initially and then hugs the 40 degree arc through Burma and Tibet.