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Old 17th Mar 2014, 16:21   #5241 (permalink)
 
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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!
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Old 17th Mar 2014, 16:26   #5242 (permalink)
 
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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.
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Old 17th Mar 2014, 16:26   #5243 (permalink)
 
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Quote:
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.
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Old 17th Mar 2014, 16:28   #5244 (permalink)
 
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IGARI-VAMPI-GIVAL zig zag

These questions were raised by Golf-Mike-Mike and Token Bird about 3 hours ago:
Quote:
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.
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Old 17th Mar 2014, 16:29   #5245 (permalink)
 
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Quote:
Originally Posted by TylerMonkey View Post
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".
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Old 17th Mar 2014, 16:29   #5246 (permalink)
 
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Quote:
Originally Posted by ildarin View Post
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
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Old 17th Mar 2014, 16:31   #5247 (permalink)
 
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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.
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Old 17th Mar 2014, 16:32   #5248 (permalink)
 
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Quote:
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.)
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Old 17th Mar 2014, 16:33   #5249 (permalink)
 
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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
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Old 17th Mar 2014, 16:36   #5250 (permalink)
 
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Quote:
Originally Posted by G0ULI View Post
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.
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Old 17th Mar 2014, 16:37   #5251 (permalink)
 
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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.
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Old 17th Mar 2014, 16:41   #5252 (permalink)
 
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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.
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Old 17th Mar 2014, 16:48   #5253 (permalink)
 
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Quote:
Pontius Navigator:
If all the new low post Ppruners posts were added up, would they reach 100?
Perhaps quantity does not necessarily equate quality.
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Old 17th Mar 2014, 16:51   #5254 (permalink)
 
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One of the comments on that CNN thread was actually useful:
Quote:
Originally Posted by someone from the thread Mark from CA posted a link to
in 1972, a plane disappeared over Alaska carrying the then-current House Majority Leader, Hale Boggs, and another Congressman. Fifty years later, that plane still has not been found. Alaska covers 663,300 square miles. The total area of the Indian Ocean is in excess of 28 million square miles. There are reports that the total potential search area for the plane is some 2 million
square miles. That's about 3 times the size of the entire state of Alaska. Not so hard for a plane to just "completely disappear" in that large a potential
area when so much of it is remote
Puts the search team's challenge into some perspective.
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Old 17th Mar 2014, 16:51   #5255 (permalink)
 
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Hornbill88 - I did trawl back and find the reference to some Twitter feed which then led to the Reuters report, which spoke of sources who wished to remain anonymous. It indicated that the postulated track of IGARI-VAMPI-GIVAL, then possibly IGREX, was put together from military radar (presumably primary?)

Still not convinced it went west at all. Came across this which quotes another unnamed source as saying they now believe it is off the coast of Perth: Combing Ocean for Flight 370 Harder Than 2-Year French Hunt - Bloomberg

I actually think they may be looking in the right area now. Ocean depth there is such that it may take years to find, though.

This article is a couple of days old but I haven't come across anything else indicating they are favouring the southern arc over the northern arc.
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Old 17th Mar 2014, 16:58   #5256 (permalink)
 
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My problem with fe hoppy's analysis is: if a person is smart enuff to heist and enroute hide a t7 they arent going to be dumb enuff to die of lack of 02 or heat.

imo.
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Old 17th Mar 2014, 17:00   #5257 (permalink)
 
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If I may offer a small ATC insight to those who know little or nothing about ATC systems, and are fixated by concepts of Primary and Secondary radar, please have a look at the following link. This might give an insight into what actually goes on. The Civil ATC world does NOT run on radar: it runs on filed Flight Plans updated by radio communications, with radar providing supplementary information for conflict resolution or sequencing in the Terminal environment.

(Aircrew and ATC professionals are generally excused from reading the link )

Flight progress strip - Wikipedia, the free encyclopedia
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Old 17th Mar 2014, 17:00   #5258 (permalink)


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Indians also think Malaysia hiding

It seems the Indian side is also frustrated with Malaysian authorities for hiding information. They are also offended with them for postulating that the a/c could have landed in andaman. To the Indians this is preposterous, for the airfields there belong to the air force and navy ; and such theories underestimate the vigilance of the indians especially as these islands play a pivotal role in India's security .
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Old 17th Mar 2014, 17:01   #5259 (permalink)
 
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Quote:
Originally Posted by GarageYears View Post
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!
Thank you very much for that link it has answered my question have they got more accurate data from the regional beam, no they haven't because pings are handled by the global beam.


One of the comments also went along the path I did. Assuming a constant speed you can calculate the maximum distance between the rings of the hourly ping, and if it is less than this distance work out some other data. I suggested if the difference between max and actual was constant it would indicate a constant (but unknown track/hdg, in which case I favoured the southern route, suicide or dead and auto pilot on.

BTW perhaps we should all bookmark the link and use it to answer any future repeat questions,
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Old 17th Mar 2014, 17:01   #5260 (permalink)
 
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Authorities reportedly looking at flight engineer, plane altitude in missing Malaysia jetliner investigation | Fox News

"Authorities are also examining the possibility that the plane flew at an altitude of less than 5,000 feet to avoid radar coverage after it turned back from its planned route to Beijing, the Malaysian newspaper New Straits Times reports.

The newspaper said officials are reviewing the plane’s flight profile to determine whether it used “terrain masking” techniques during the time it disappeared from radar coverage.

"It's possible that the aircraft had hugged the terrain in some areas that are mountainous to avoid radar detection,” an official told the newspaper. “The person who had control over the aircraft has a solid knowledge of avionics and navigation…it passed low over Kelantan, that was true.”

Kelantan is a province in central Malaysia."


If this news is correct, it contradicts the hypoxic pilot theory, unless that happened after another climb out. Passengers must have been out or controlled because they would likely notice being at less than 5000'
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