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-   -   Malaysian Airlines MH370 contact lost (https://www.pprune.org/rumours-news/535538-malaysian-airlines-mh370-contact-lost.html)

cribbagepeg 15th Mar 2014 20:03

satcom question
As most birds are "bent pipes" and generally connect the incoming RF signal to an onboard transmitter on a coresponding downlink frequency, any doppler shift present in the uplink one should be present in the downlink one. Now the trigonometry suggests a tiny or even undetectable doppler shift, but this would be larger at the extremes of a beam's footprint. Any thoughts?

aviator1970 15th Mar 2014 20:04

Whats the big deal about the non standard R/T terminology? seriously? routine usage of nonstandard words in locally acceptable language is a norm.... Namaste is used in Indian airspace by all airlines... as is bye or Khuda Hafiz in other areas.... whats the big deal?

rog747 15th Mar 2014 20:04

is this right - in simple terms for many

Satcom are maybe providing enough satellite fixes to establish where this aircraft went - BUT you need 3 satellite fixes on each ping given off for an accurate fix - seems they only have 2 on many of them - The ACARS was switched off to SEND data but the system stays on and still searches for satellites and thus gives off its location to satellites

Satellites picked up a signal from the B777 at 08.11 local time some 7 hours after the transponder was switched off but could not get an accurate 3 point SAT fix -
That is why now there are 2 corridor areas of search because the satellites only got partial position without the 3 fixes -
so they are looking up towards the Bay of Bengal and Kazakhstan and south west down towards the Indian ocean -
at this point 7 hours on in daylight, the fuel remaining would be very low.

(unless more fuel had been loaded on deliberately at KUL)


Return 2 Stand 15th Mar 2014 20:06

If it had been flying 7 hours between loss of contact and the ping on the arc, the southern arc would seem too close wouldn't it? Assuming it had been flying in a straight line it could easily have gone as far as Perth?? The far end of the Northern Arc makes more sense time wise?

overthewing 15th Mar 2014 20:06

There is no possible way the US hasn't requested the data for any unidentified planes being picked up on the surrounding countries radar systems
I'm sure that's true, but it depends on there actually being data to supply, I would think? Given what we've learned from all this, there seems to be patchy alertness and coverage in that part of the world. Anecdotal evidence is that Myanmar can be overflown without challenge.

rampstriker 15th Mar 2014 20:07

However, it is really sloppy software to generate superfluous pings. If there is not data to transmit, then there is no reason to waste battery power and bandwith to see which server could take your call if you had a payload to send, like a sign on request.
Not if you look at it from the standpoint of the vendor who is selling a subscription service to monitor engine data during cruise. They would want the connection to be robust and available without the customer having to configure anything if they did purchase the package. A check ping every 30 mins is not overkill in this case. The ping also includes the aircraft's digital unique identifier (like a MAC address), so the vendor could activate the service instantly from their server side.

But it sounds like very few folks were aware of the pinging--it was kinda hidden away in the software.

Edit: The pings originate from the Inmarsat satellite system ACARS server, not from the ACARS software on the plane and are sent hourly to check the Satcom connection.

DuneMile 15th Mar 2014 20:07

Yes, commercial line pilots use "Roger that". All the time. ATC and commercial pilots say it regularly.

AirDisaster.Com: Air Traffic Control Transcript: American 587
Aviation Safety Network > Accident investigation > CVR / FDR > Transcripts > ATC transcript Thai Airways Flight 261 -
Aviation Safety Network > Accident investigation > CVR / FDR > Transcripts > ATC transcript Swissair Flight 111 - 02 SEP 1998
Comms Transcript
Aviation Safety Network > Accident investigation > CVR / FDR > Transcripts > Singapore Airlines Flight 006 - 31 OCT 2000

FE Hoppy 15th Mar 2014 20:08

The range for the first ping after last radar contact can show which direction is most likely. The range of that arc will put the aircraft either closer or further away from the radar that had previously tracked them.

Rerun 57 15th Mar 2014 20:12

Which airfields, capable of taking a 777 are there in Turkmenistan etc?
Suppose the hijackers just want the aircraft?
How likely is it that the aircraft could make it to a former Russian Republic airfield and land without comment from locals? Where would it have been dark at points near maximum endurance?

Ramjet555 15th Mar 2014 20:13

Flight MH370 Disintergrated at FL350 at last Transponder report
It appears that most of the worlds journalists and managers of the search have failed to do any "air of reality"checks with this story. The searchers have failed to think logically with the exception of the Chinese Government and the Vietnamese Government who have done an incredible job and who both deserve an honourable mention for their accurate reporting.

The Transponder and Flight Data STOPPED indicating a catastrophic explosion. The WRECKAGE DEBRIS was repeatedly observed, photographed and provided to searchers. Boats arriving could not find it. Those Photographs did not LIE, they were not fabricated. They are REAL EVIDENCE.

Oil Rig Worker Michael McKay was the First and Only Eye Witness to the explosion and his "Bearing confirms that it was along the flight path near where the Transponder Stopped.

The Satelite "PINGING" by Imarasat shows it ENDED in the same area as where the Transponder Stopped.

The problem is, Imarsat information has got the TIME wrong, it was NOT AFTER the accident time but AT the accident time the last reported "PING" was heard.

There appears to be a miscalculation of time or , the FL MH370 flew in circles in the same area for 7.5 hours and then crashed in the same area.

Imarsat is not showing an accurate map. The map shown is misleading and fails to allow for known errors that if allowed for place the last signal in the same area.

The Primary radar is dubious, and does not show clear evidence to support any flight away from the last known position.

There is NO evidence to support a highjacking.

Any search manager should take a close look at that Imarsat informatio, demand to see video or stills of that primary radar BEFORE assuming the "Highjack" theory and or wasting many millions of dollars searching in any area OTHER THAN

an Underwater search in the Immediate area after the transponder stopped.

At around 500 Knots, the debris will have travelled about 5 miles forward of the last known position along the Planned Flight Path and it is there that the heavy wreckage will be found.

The floating Debris has moved at about 50 miles a day and some maritime science needs to be used to determine from wind and currents since the crash time as to where that debris might be now.

The world owes an apology to the Governments of China and Vietnam for their incredible work to date and for the arrogance of the west to ignore their vital evidence.

Dito for Michael McKay who is the Sole Witness to this mid-air explosion.

The US navy needs to take its own appraisal of the above information and start an

underwater search centered on 5 nm ahead of the last known Transponder position on the Flight Path Track.

Image of debris


Imarsat image of range of error

LadyL2013 15th Mar 2014 20:13

'why has no one come forward if it is terrorism'

Because look how much people are taking about it, speculating, how focused the world is on it. Terrorists love publicity and this is giving to them in bucket loads even if the actual people haven't announced themselves.

That is of course assume it is an act of terror. Personally I'm subscribing to the idea of 'we don't know and won't know until we have more evidence' side.

overthewing 15th Mar 2014 20:13

Planned and unplanned attempts but is turning the aircraft round and flying in the opposite direction for many hours until it ran out of fuel typical suicidal planning behaviour? I don't think it is.
I'm not sure there is such a thing as 'typical suicide planning behaviour'. From my own exposure to the subject, suicides can get themselves 'into position' and then take a long time to commit themselves to the final act. And I can imagine that letting the place run out of fuel and crash, in some ways might make it into an accident rather than suicide in a distorted mind.

Aireps 15th Mar 2014 20:16

Originally Posted by D.S. (Post 8378737)
The pilot of that Japanese plane is quoted as saying

“We managed to establish contact with MH370 just after 1:30 a.m. and asked them if they have transferred into Vietnamese airspace,” the pilot reportedly told New Straits Times. “The voice on the other side could have been either Captain Zaharie (Ahmad Shah, 53,) or Fariq (Abdul Hamid, 27), but I was sure it was the co-pilot."

The "Japanese plane" you're mentioning, may in fact have been MH88: Post 3875

Chances are that the MH88 pilot knew the MH370 (co-)pilot he was talking to.

Ramjet555 15th Mar 2014 20:18

It's nonsense.
The circle shows a line basically right through the last known position within a range of acceptable error.

According to Imarsat, it must have remained in the same area and ran out of fuel in same area, as the last transponder signal.

What we have is an incredible error in assume the TIME of the last "ping" to be 7.5 hours AFTER the transponder stopped.

No, that last ping from my read occurred about the same time as the last transponder report.

OleOle 15th Mar 2014 20:22

Techgeek – Re:17:11 out of range of POR

Point taken. But if at that time MH370 was too far west to be seen by POR, that fact in itself would proof that MH370 was going west as indicated by primary radar.

rigbyrigz 15th Mar 2014 20:25

OK, maybe the mod will allow a question for one of the experts to comment on or answer, on a point that seems important but so far overlooked (at least here).

We have transponder/comms cut off, with some doubt as to whether that was "deliberate" or the result of some electro-mechanical failure/s.

We have a somewhat suspect "alright good nite" hand-over AFTER that.

So MAYBE that is telling. But what about: ATC Vietnam hears hand-over transmission.

Does he also see or note that this a/c handing-over is from a FL he does not see because the transponder is off... would he note that and question that??
(as being alarming to get the hand-over in such circumstances)

MG23 15th Mar 2014 20:26

Originally Posted by Ramjet555 (Post 8378815)
The problem is, Imarsat information has got the TIME wrong, it was NOT AFTER the accident time but AT the accident time the last reported "PING" was heard.

I'm sure one of the first questions Inmarsat asked was 'is there any way these times could be incorrect?' (e.g. something in the system accidentally resending old messages).

techgeek 15th Mar 2014 20:28

Define ping
Warning - the following is a bit off topic for an aviation forum but it is relevant to this thread.

"The term "ping" doesn't refer to a particular mode of transmission but a particular type of transmission. That is, a ping refers to the content of the data packet. A ping is either some version of an ACK or a "keep alive" message.

Typically one node broadcasts a message to another node. The node receiving node either returns an ACK (acknowledgement) or a keep alive. Which it returns depends on design specifications. It is something said that when this roundtrip has been successfully completed it is called a "handshake". However, a handshake contains more data than ping because a handshake contains data regarding the network protocol"
A reasonable generalization but not really accurate. Protocols use very explicit language to define their operation (e.g. ISO 8208 CALL REQUEST, ISO 10747 KEEPALIVE). In this case the protocols are pre-determined and there are quite a few of them (AMSS, ISO 8208, IDRP, X.25, X.121)! These protocols are layered with one depending on another for proper operation.

It is important to understand the concept of layers in networking. Microsoft has a good link here if you want to learn more about network layers in general.

This pdf published by Boeing (slide 12) shows an architectural diagram of ACARS. Blocks denote "layers" stacked upon one another. There are 3 stacks depicted ("Communications Management Unit", "Datalink Service Processor" and "User Ground System"). You can think of data flowing up and down each stack and horizontally between them. Note the dashed line connecting "Satellite Data Unit" (in the airplane) and "AMSS GES" (satellite ground station). The satellite itself is not shown but you could think of it as represented by the dashed line. This is where the "ping" is occurring.

luoto 15th Mar 2014 20:28

Swedish media picking up reports from other media that some pax might have had flight training in Sweden. Might be picking at straws etc but Missing Malaysia Airlines jet: Investigation paying 'special attention' to Chinese Uighur passenger

Whiskey Mike Romeo 15th Mar 2014 20:28

At last HF is being mentioned
I have followed this thread from the beginning and have read all posts that have not been deleted before I got to them.

About an hour ago, while reading yet another post about illicit communication with ground accomplices via satellite phones or cellphones, I starting shouting at my screen "Has nobody heard of HF?".

Then I came across Mike Banahan at 1119z and then J R Barrett at 1756z and realised that I was not alone in my thoughts.

As pointed out, HF aeronautical radios and their associated antenna tuners have wide band capabilities and used discreetly may go unnoticed.

Why would hijackers or rogue pilots need to risk drawing attention to themselves by taking hand held VHF on board when there are already decent powerful VHF COM sets on board connected to external antennae? Why risk using a pipsqueak radio whose batteries might die at the crucial moment? All that is needed is to pre arrange a selection of VHF channels which have been researched as not being in use wherever the hijacker intended to travel.

What has not been mentioned by the previous posters suggesting HF is that nowadays huge chunks of HF spectrum can be recorded using SDR and played back at leisure, with particular attention to transmissions sticking out as unusual. Likewise VHF, if anyone is recording it in that way.

Just a thought on "Roger that". Might not a pilot being leaned on by a third party break with convention in order to draw attention from ATC but not from a hijacker? In this instance could that have been too subtle?

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