Malaysian Airlines MH370 contact lost

[geneman]

To the precision of the ping arc:

GSM base stations have to know the timing delay between cell phone and base station. This timing delay is determined by "pinging" them. The precision of this measurement gives the distance between phone and base station with an accuracy far better than 550 meters.

That is an example for what precision is possible with everyday consumer electronics. I don't know the exact specs for inmarsat, but taking into account unfavorable geometry, I would expect a precision in the range of better than 5 km.

Given that the satellite is at an altitude of about 36,000 kilometres, a 5km precision would be about +/- 0.014% of the distance, which would be truly remarkable.

[formationdriver]

MODS quit

Reading the last 70-odd pages of posts I suspect the PPRuNe moderators have been magically transported onboard # 370.
Come back.
Please.

[Towhee]

.
So let me get this straight. Because the Captain is wearing a shirt declaring "Democracy is Dead" in protest of the overall UMNO/BN approach to government (and the obvious treatment of Ibrahim), and is a supporter of Ibrahim he is now more strongly considered to be some kind of hijacking suspect? What century are we in?

The pilot's viewpoints on politics and support of PKR are nothing special. There's quite a sizable contingent of people in MY with the same opinions and support for the opposition has been growing for years.

Secondly, Anwar Ibrahim is *not* jailed. The accuracy of modern media and "journalism" these days is just flat out appalling. It's no longer about being precise or accurate - it's completely driven by eyeballs.

Terrorists have won, haven't they? Time to burn some witches.

:


It's outrageous to impugn the pilot based on his political support for an opposition candidate. Opposition, factionalism, dissent is the essence of democracy.

Unsurprisingly, these scurrilous allegations seem to be promulgated by the Daily Mail.

The DM is an aggressively right wing tabloid that mixes infotainment with ultra.conservative diatribe. It has a Nazi supporting lineage. Its US readership consists of white trailer trash and devotees of Faux news.

Malaysia is still a quasi authoritarian nation with limited press freedoms. It lacks a completely independent judiciary. It's had one party rule for way too long.

Reputable publications have covered the Ibrahim saga for years, so it surely doesn't take this tragedy to advertise the deplorable situation.

[VH_BIL]

This is a fairly nice layman's description of 'ACARS pings' that have been wildly misunderstood on this thread...

Understanding ?satellite pings? ? Tim Farrar - The Malaysian Insider

For those still reading - this gives an overview of ACARS:
https://www.sita.aero/file/1569/Aircom_new_generation_services.pdf‎

There are some AEEC standards documents in that document that contain the protocol definitions of ACARS.

From the document: "the AeeC Characteristic 741 for the satellite Data Unit specifies the use of an X.25 based protocol, which Inmarsat originally intended to be used for packet data communications across the AMss network. this complies with the protocol specified in the ICAO AMss standard described later in this document."

So it uses X.25 - there's some DTE address fields there.

It seems the ACARS "SATCOM" data stream in this aircraft was based on the Inmarsat Swift64 service and these terminals use an ISN which is a "12 character Inmarsat Serial Number" - so there's the layer 1 ID.

Although I haven't found those standard definition documents for this service, it seems like these 'pings' would be addressed directly to a terminal address (i.e. unicast to the specific ISN) rather than some random broadcast/multicast across the whole beam/coverage area (pointless thing to do).

X.25 can do the same thing - and the AeeC can do the same on top of that - apparently (according to AEEC 620 standard for ACARS) it uses a 7 letter IATA address (from the aircraft registration mark).

So there are three different addresses at three different layers that would be able to identify the signalling terminal.

As an aside, especially when talking about mobile/cellular phone systems, just because you know something about one system does not mean every system works similarly - (this thread contains mounds of rubbish on this topic).

Remember that there are 2G, 2.5G, 2.75G, 3G, 4G, LTE systems using Analogue, TDMA, CDMA, W-CDMA, FDD, TDD, etc all on different bands, with different design trade-offs and varied methods of implementation and completely different performance characteristics (and I haven't even mentioned the Chinese varieties like TD-SCDMA).

BTW - in the beginning "ping" was a UN*X utility designed to send ICMP packets for IP networks - named after the Sonar 'ping'.

[OleOle]

Possible motive

slats11

Good assessment of possible motives. What's missing is
- something spontaneous
- something not going according to plan
- a change in plan.

[G0ULI]

The Earth is Unimaginably Vast

For those who are frustrated at the apparent inability of modern technology to find a large passenger jet even after days of searching it may help to consider the following.

The total surface of the earth covers around 510 million square kilometres.
Water covers 361 million square kilometres and land 149 million square kilometres.

Assuming that a 777 jet (or wreckage) covered an area of 50 by 50 metres (a large over estimate), then that still only represents 1/400th of a square kilometre.

Given that the theoretical range of the jet covered nearly a third of the earth's surface (call it 150 million square kilometres), investigators are looking for a single point measuring at best 50 metres by 50 metres in all of that area. So 150 million square kilometres times 400 = 1 point in 1,600,000,000 possibilities at best. That is assuming the aircraft or wreckage are visible from the air. If it is under water or has made a smaller impact crater on land, the odds become even greater against locating anything.

Obviously the investigators are doing everything in their power to try and reduce the odds by calculating the most likely flight path, but the search is going to take a long time.

Yes, we can fly around the world by jet in under two days, or in 90 minutes with a spacecraft in low earth orbit. But the earth is still unimaginarily huge, despite the wide angle shots from ISS and the blue pebble photo taken from the moon (also with a wide angle lens).

[Wirbelsturm]

Regarding dispersal missed out that the idea was they were a gel to slow down the release and dispersal.

I don't disagree. As a former SAR captain I have found the dye to be fantastic however it has a lifespan. The trade off between liquid dispersal and the slow release of a gel limiting the size of the visible area is one for the scientists.


I would guess that if the search area was located in the wrong area then the intervening time between dispersing passive aids and looking for them would defeat both liquids and gels.


Self detaching ELT's and SARSAT beacons are not very common on commercial airliners as they are, generally, not out of contact for as long as this scenario therefore the area of search is normally smaller and more located.

[OleOle]

Given that the satellite is at an altitude of about 36,000 kilometres, a 5km precision would be about +/- 0.014% of the distance, which would be truly remarkable.

Relative precision doesn't matter. If you can measure 1 microsecond precisely then you can also measure 250001 microseconds with the exact same absolute precision.

[GarageYears]

A very GOOD explanation of the INMARSAT system

For those who seem to be struggling with the SATCOM/INMARSAT operation the following gives a very good overview:

TMF Associates MSS blog » Understanding ?satellite pings??

Hopefully this will put-to-bed the repeated questions regarding this!

[rigbyrigz]

JUST to summarize what I gleaned from Richard Quest's painstaking questioning on-air of the test pilot:

ACARS can be "degraded" from the screen, by selecting VHF OFF or SATCOM OFF or DATALINK OFF.

That would allow a 1:07 reporting (ON) and no 1:37 report (OFF).

But unless the CB is pulled or cut, the outside antenna receiver would remain active. The Satellite "ACARS handshake attempt" faint-ping would find the antenna (and the a/c) and make the report of pings we have seen and heard so much about until 8:11 AM.

[Dont Hang Up]

It seems to me that if a passenger aircraft is flying on established routes and at established flight levels with its transponder deactivated, provided it does not trespass into secure airspace, it will be ignored by military radar and invisible to ATC. This is rather worrying if I am correct.

You are wrong if you are assuming military have only primary and civil have only secondary and they never speak to each other.

Military will almost always have both. They may not all have the latest Mode S & ADS-B, but certainly Mode A/C plus military IFF modes. So they will see any civil transponder that is switched on. If an aircraft on a recognised civil route is not transponding they will notice. Indeed it is one the key incursion methods they should be looking for.

Civil controller will often have both also.

And in many states it is not uncommon for mil and civil controllers to be sitting in the same room. Or even for mil personnel to be offering the civl ATC service.

[Hornbill88]

IGARI-VAMPI-GIVAL zig zag

These questions were raised by Golf-Mike-Mike and Token Bird about 3 hours ago:

Quote:
Except (I understand) they have primary radar "confirmation" of a north-easterly course after the westbound one (ie IGARI - VAMPI - GIVAL ....) That was what I was trying to figure out. I recall reading that days ago but was unsure as to where that info had come from, and if it was primary radar, was it later confirmed by the Inmarsat ping data. Since they have only released info about the final ping it's not possible to tell.

I'm going to trawl back through this thread and see if I can find the reference regarding the theory they flew IGARI-VAMPI-GIVAL.

The authority is Reuters report at 8.11am GMT on Friday 14th March: "Military radar-tracking evidence suggests a Malaysia Airlines jetliner missing for nearly a week was deliberately flown across the Malay peninsula towards the Andaman Islands, sources familiar with the investigation told Reuters on Friday.
Two sources said an unidentified aircraft that investigators believe was Flight MH370 was following a route between navigational waypoints - indicating it was being flown by someone with aviation training - when it was last plotted on military radar off the country's northwest coast."

I'd quite like to hear a journalist ask for confirmation of that in the next press conf to bring the "sources" out into the open.

[cockpitvisit]

Originally Posted by TylerMonkey

The oil rig sighting ..... I have never seen a time quoted yet when he saw this.

Here is the email from the oil rig worker that is being quoted everywhere.

It doesn't specify the time - just says "the timing was right".

[oldoberon]

Originally Posted by ildarin

Of course, enough dye to be useful in the open ocean would weigh enough to prevent the airplane from taking off.

THAT, I admit, would certainly prevent future accidents...

is that comment based on knowledge of the size and weight of a gel or solid block or just straight forward dismissive guess work/comment.

I googled various bits and wouldn't be surprised if the idea came from shark repellant dyes

reads this patent explanation seems they are getting a good time distance coverage from a bout 29 SMALL blocks of dye attached to a the diver
So upgrade them to the weight of a pax and what could you get, plus make the contents wax covered so they get dissolved at staged time periods.

Patent US4080677 - Portable diver distress signalling device - Google Patents

[bigglesbrother]

Thank goodness for FE Hoppy and his common sense: his posts are well reasoned amid a myriad of posts which do little to provide an explanation for the disappearance of MH370.

As a sometime Laker DC-10 pilot and later as a pilot for many years of Gulfstreams fitted with upmarket avionics I can claim some familiarity, albeit getting very dated, with the MH370 night transit scenario.
Having followed the huge number of pprune versions of events for MH370 we had some non pprune chat three days ago amongst fellow aviators & produced this analysis ...... nothing seems to have changed since then.


1 Aircraft now appears to have kept flying until fuel exhaustion – about 6-7 hrs.

2 On autopilot – or it would probably have crashed earlier.

3 All major comms and auto electronic readouts disabled: BUT it seems that auto R-R engines monitor satellite report pinging cannot be deselected manually.

4 One of the crew is the culprit? Aircraft depressurised and all except hijacker pass out & die due to lack of oxygen. Eventually he goes too through cold or running out of his own oxygen supply.

5 Hijacked, but did hijackers have enough technical knowledge to disable all major systems yet keep flying?

6 Aircraft in the sea somewhere.

7 USA knows far more than it has disclosed.

All above are our best guesses on current hugely varied info.

[geneman]

For those who seem to be struggling with the SATCOM/INMARSAT operation the following gives a very good overview:
TMF Associates MSS blog » Understanding ?satellite pings??
Hopefully this will put-to-bed the repeated questions regarding this!

Thanks for the tip. I checked this website and found the following conclusions, although I obviously can't vouch for their accuracy:

"Key point 8: The position of the aircraft is being estimated based on the signal timing/power measured at the satellite. Its not based on the data content of any message and is not highly accurate.
... it is unlikely that the measurements are more accurate than within say 100 miles." (Emphasis mine.)

[Livesinafield]

If the PSR last had it tracking towards the Andaman islands then i would say the "northwestern corridor" as they call it is much more likely than the Indian ocean theory

[cockpitvisit]

Originally Posted by G0ULI

But the earth is still unimaginarily huge, despite the wide angle shots from ISS and the blue pebble photo taken from the moon (also with a wide angle lens).

Exactly. You can fit over 600,000 of such airplanes around the equator.

It is like searching for a small ant on a square mile of mostly rugged terrain.

[Howard_500]

Putting the PPRuNe-journalists infinite loop to a good use

I have been reading this topic with great interest for more than a hundred pages now.

As some mentioned earlier, the MH370 event has brought here a lot of curious, non-pilot people (including myself), and among them, journalists, who relay information they read here, information which is in turn relayed here by news readers.

My question is : wouldn't it be better for everyone, if the prime users of this forum, namely aviation professionals, took advantage of this "infinite loop" to influence the press in doing some more serious work ?

Example : i have read a lot of you complaining about the inaccuracy or uselessness of some press conference questions. Maybe you could make a short list of precise, logical questions for the journalists to ask, that would clarify some points and reduce the amount of confusion.
At least to obtain, for the whole world reading all this, some bits of certainties re this unprecendented disappearance.

Because, as this whole story begins to resemble George Boolos's "hardest logic puzzle in the world", the main fact remains that 239 people are still missing.

[NiclasB]

Scenario at end of fuel exhaustion

Apologies if this question has been posted already. Have read most but not all previous posts.

Assuming the "incapacitated crew, flying on AP at FL 2XX until fuel exhaustion" scenario, could some with technical knowledge on the T7 supply the details of how the scenario would unfold at the "...until fuel exhaustion" end?

1) Would both engines shut down at approximately the same time, i.e. do they have a common fuel source, or could one run, say 15 minutes longer?
2) At which point does the AP disconnect, immediately as the first engine shuts down or does it stay connected in some degraded mode?
3) What is the likely profile during descent? Nose-dive to (beyond?) VNE or are there any protections to prevent over-speed? Fly as close to VMD as possible? Follow-up: How much time would the crew have in oxygen-rich air, e.g. below FL100, to recover? I'm guessing not much.
4) Given the above scenario, is the high or low vertical speed impact the most probable outcome?

I would assume a high vertical speed impact on the last questions, which would translate to a small debris field, correct? That would make the search effort harder, especially over the ocean or un-populated high terrain.

Still hoping for a non-foul play reason for the missing plane...

PS. Many thanks to all that have contributed with technical and/or operational input to this thread! As a GA pilot with basic ATPL knowledge, some posts give very good chances for self-education. Other...eh, less so.