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Malaysia Airlines Flight Goes Missing En Route to China - Flight MH370

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  • Originally posted by TNHunter View Post
    ADS-B is NOT a transponder function. It is separate avionics. It has it's own GPS receivers and formulates it's own data packet extensions. It is broadcast as an extension to the Mode S transponder making it a Mode ES transponder. Mode S does not broadcast a position within it's data packet. Baro altitude is part of the data packet as well as ICAO codes, Flight numbers and much more. ADS-B does NOT use GPS altitude, it uses BARO altitude or Mode C information.
    So switching off the transponder also switches off the broadcast of ADS-B but not necessarily the ADS-B itself? Is it possible for a pilot to change the transponder ID so it looks like another plane?

    Comment


    • Originally posted by mcjensen View Post
      I will add to what I said before:
      Lets be real folks, there was no fire, no smoke, no flames, no mechanical failure, no catastrophic failure...this was an abduction..
      Yes... it's got to be Aliens! Where's Scully and Mulder when you need them ?

      A list of conspiracy theories would not be complete without the obligatory alien abduction narrative. Alexandra Bruce, of Forbidden Knowledge TV, has used flight mapping website Flightradar as an example of extra-terrestrial involvement in the disappearance of MH370.

      Pointing to a video by “intrepid citizen reporter” YouTube user DAHBOO7, Bruce claims radar readings in the clip “captured signals from what for now, can only be termed a UFO”.

      The video recreates the plane’s final moments and shows a “mystery object” flying at an accelerated speed which is in fact marked as the Korean Airlines Flight 672.

      Others however have needed less convincing on the alien-as perpetrator forefront.

      http://www.independent.co.uk/news/wo...r-9200242.html
      www.ADS-B.ca

      Comment


      • Originally posted by 1090 MHz View Post
        Yes... it's got to be Aliens! Where's Scully and Mulder when you need them ?
        No need, I found it:

        sunday-sport-mh370.jpg

        "Problem solved!"

        Comment


        • Originally posted by TNHunter View Post
          Interesting read. Well within fuel range.

          http://www.wnd.com/2014/03/top-gener...r-missing-jet/
          Sounds realistic... what about the passengers then? Any chances for them to survive? Scared even to think about it...

          Comment


          • Originally posted by smay69 View Post
            Is it possible for a pilot to change the transponder ID so it looks like another plane?
            Yes it can be changed,

            ICAO 24-bit address

            Mode S equipment on aircraft are assigned a unique ICAO 24-bit address or (informally) Mode-S "hex code" upon national registration and this address becomes a part of the aircraft's Certificate of Registration. Normally, the address is never changed, however, the transponders are reprogrammable and, occasionally, are moved from one aircraft to another (presumably for operational or cost purposes), either by maintenance or by changing the appropriate entry in the aircraft's

            Flight management system http://en.wikipedia.org/wiki/Flight_management_system
            www.ADS-B.ca

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            • Originally posted by Cambridge
              breakingnews on bbc tv in uk is that australia says it detected the pings from mh370 and is searching towards south pole , no im not joking that vague info but thats what was said..so again tomnod.com we need new images for new suspect area
              Funny there's not a word about this "revelation" on any Australian media site that I've looked at and they are on the case 24/7. Nothing that I can find on the BBC website either.

              Comment


              • Originally posted by smay69 View Post
                So switching off the transponder also switches off the broadcast of ADS-B but not necessarily the ADS-B itself?
                ADS-B is a specification, not a thing. The device on a plane that would implement the "ADS-B out" specification is the transponder.

                Is it possible for a pilot to change the transponder ID so it looks like another plane?
                Not without specialist tools. Under the "never say never" rule this might possibly be done while the plane is in flight, but isn't very probable.

                Comment


                • Originally posted by SpaxmoidJAm View Post
                  No if the inmarsat system time stamps its data and there is a handshake before data starts(a known set of comands to establish the link) and you know how long that command takes to process or there is a deliberate wait time before a reply is given (i.e. plane receives command processes but wait 200ms from receiving the command to sending its reply) you can deduce distance from the satilite by the two way travel time.
                  An easier way to deduce all of this is instead of try to calculate blind from just the pings and a lot of assumptions (cpu delays etc), is to crunch data from other 777-200's with the exact same system installed flying all around the areas of interest and profile their pings while you have a very accurate measurement of their actual position. Then compare with the last pings you have (in terms of power and timings) and see what that corresponds to in the real world...There are a lot of Malaysian 777-200s leaving KL every day in all directions...there is already a TON of retroactive data for this (in fact there is for the plane that is currently missing too)...actually doing it this way with enough data may allow you to not only predict distance from the satellite but estimate heading and speed as well since timings will be slightly different for an object moving away. Is it a single ping packet every half hour or a series?
                  Last edited by smay69; 2014-03-19, 23:28.

                  Comment


                  • Originally posted by airnrail View Post
                    Funny there's not a word about this "revelation" on any Australian media site that I've looked at and they are on the case 24/7. Nothing that I can find on the BBC website either.
                    Same here. Nothing on US TV, and no sign of it on the BBC news web site.

                    Comment


                    • Originally posted by SpaxmoidJAm View Post
                      No if the inmarsat system time stamps its data and there is a handshake before data starts(a known set of comands to establish the link) and you know how long that command takes to process or there is a deliberate wait time before a reply is given (i.e. plane receives command processes but wait 200ms from receiving the command to sending its reply) you can deduce distance from the satilite by the two way travel time.
                      Yeah, I suppose if you forget about timestamps on the aircraft side, which I think was overcomplicating it, position could be estimated with decent accuracy based on latency for the round trip 'ping' response, minus known delays inside equipment (this part testable in a lab).

                      Edit:

                      smay69 your post further validates it.

                      flyingduck: I thought about using amplitude, but seeing as that could be affected by weather, and because it's a 2 way communication, it seemed better to use latency. Still could be amplitude though, and it would be useful for validating your calculations.
                      Last edited by xlynx; 2014-03-19, 23:31.

                      Comment


                      • Originally posted by SpaxmoidJAm View Post
                        No if the inmarsat system time stamps its data and there is a handshake before data starts(a known set of comands to establish the link) and you know how long that command takes to process or there is a deliberate wait time before a reply is given (i.e. plane receives command processes but wait 200ms from receiving the command to sending its reply) you can deduce distance from the satilite by the two way travel time.
                        Correct!

                        I think the confusion is arising because the "ping" used in the context of the missing MH flight is being confused by the UNIX/Windows/DOS Networking ping command (ie, ping 192.168.1.1). Below is link that explains just that:

                        http://theaviationist.com/2014/03/16...ars-explained/

                        "Ping

                        A Ping is a quite common term for IT Networking. It refers to a utility used to test the reachability of a host on an IP network and measure the round-trip time (RTT) of the packets even if it is more frequently associated to the data messages themselves, or “pings”.

                        Similarly to what happens on a Local Area Network, satellites send pings (once a hour) to their receiving peers that respond to it thus signaling their network presence. Hence, these pings are no more than simple probes used to check the reachability of SATCOM systems aboard the planes.

                        Based on details recently disclosed, the last response to a satellite ping, was sent by the SATCOM aboard MH370 at 08.11AM Malaysia time, some 7 hours past the loss of contact with the Boeing 777.

                        From the analysis of the time between request and responce it is possible to work out the distance of the plane which is a circumference of certain radius from the satellite based on which, two possible routes were drawn by the investigators."

                        Comment


                        • Originally posted by cretanrunner View Post
                          Thanks for reminding me what I said. Let's just forget this conversation shall we? Maybe you are a troll, maybe not. I was having a conversation with someone else about Goodfellow's theory, and you dived in on one specific detail. Troll-like behaviour possibly, but never mind.

                          Now, why don't you elaborate on what you believe?

                          You seem to be saying that because the Yanks and Aussies seem to be concentrating on a particular area, that must be where the plane went. You may well be right, and I don't have any info that says either way. But what about the claim, (maybe rubbish again), that the plane headed west to the Malacca Strait and was logged there by radar?

                          What is the latest consensus about an actual flight path? Do we know, or are we all just speculating? If it did go west to the Malacca Strait, the Aus/US search area looks wrong. If the westerly flight path never happened, then do we have info, (rather than assumptions), about a flight path towards WMKN, then onward to west of Australia?

                          I'm not pretending I know any of these answers. But if someone does it would be helpful to know. Hopefully the authorities have better data than what is being thrown around here.

                          Presumably, you are thinking that they had a problem, (fire), that knocked out comms. They tried to get to WMKN, but having set that course on autopilot, were overcome by fumes or whatever, and the plane just flew on till it ran out of fuel. Could well be.

                          The other thing that is so vague is whether or not the comms were switched off deliberately or not.
                          I am saying that the best way to know what can be known from the data that the NTSB / Australian have is to observe the search actions of the Australian search. They have moved the search from an area from around the Cocos Islands to an area south and west of Australia (centered on a latitude of about S42 degrees). And it is within this area that the aircraft most probably crashed - that is the plane most probably did not fly north.

                          The Australians have drawn a four sided figure which defines the search are. The Inmarsat radial dimension of the figure can be used to estimate the precision and accuracy of that data. And the length along the circumference represents the uncertainty in the endurance and track of the aircraft.

                          The Australians have been requested by the Malaysians to perform this search and I do not believe that they, the US and New Zealand are prepared to be jerked around and send their planes out in the middle of the Indian Ocean on no good basis. So, I believe, they will have talked to the technical people at Inmarsat, MAS, the Thais and the Malaysian Defense Dept. So they probably have the best data and have done the best analysis (or even the only analysis) of the data.

                          Other less ephemeral data that they would have access to would be the general capabilities of the PRC's, India's, Pakistan's and the US's (in Afghanistan) air defense radar systems.

                          Plainly the NTSB/ Australians do not give credence to some of the statements made by the Malaysian administration, much if which is inconsistent and has been negated. For instance, MAS negated the administration's statements regarding the ACARS data.

                          I think that the NTSB / Australians believe that the plane turned back to Malaysia but, for reasons unknown, failed to land there and flew on a track that was the extension of the return track to Malaysia. Hence they are searching where they are.

                          Comment


                          • Originally posted by TNHunter View Post
                            ADS-B is NOT a transponder function. It is separate avionics. It has it's own GPS receivers and formulates it's own data packet extensions. It is broadcast as an extension to the Mode S transponder making it a Mode ES transponder. Mode S does not broadcast a position within it's data packet. Baro altitude is part of the data packet as well as ICAO codes, Flight numbers and much more. ADS-B does NOT use GPS altitude, it uses BARO altitude or Mode C information.
                            Thanks! that answers #2. It's fully plausible the radar transponder, ADS-B and ACARS equipment all offlined at 1:21.


                            Originally posted by MIT EE View Post
                            From the analysis of the time between request and responce it is possible to work out the distance of the plane which is a circumference of certain radius from the satellite based on which, two possible routes were drawn by the investigators."
                            Thanks! That's the answer to my question #4 then.



                            Now, my only real remaining question is #1, reworded:

                            Is there any evidence ACARS was switched off and did not fail? Was MH370's ACARS equipment built to send a disconnect signal to indicate a graceful shutdown?

                            This seems a crucial question, because the original suspicions were based on a faulty assumption about ACARS offline time and the likely incorrect belief this occurred before the last comms and transponder offline. There's still the reprogrammed flight computer, but is that a strong enough case to focus on possible hijacking rather than equipment failure?
                            Last edited by xlynx; 2014-03-20, 00:12. Reason: "re" not "pre"

                            Comment


                            • Originally posted by Speed Daemon View Post
                              ADS-B is a specification, not a thing. The device on a plane that would implement the "ADS-B out" specification is the transponder.


                              Not without specialist tools. Under the "never say never" rule this might possibly be done while the plane is in flight, but isn't very probable.
                              Speed Daemon is correct. It would take a technician with the avionics on the bench to change the ICAO address. The ICAO code is like a VIN code assigned to a car. It is supposed to be assigned to a airframe. The issue with ABS-B is it requires receivers and they have an effective line of sight range of about 250nm (when the aircraft is at higher altitudes). At this time there are no space based ADS-B receivers. Also, ADS-B is being set to a world wide standard but has not yet been implemented world wide. NORMALLY if the 1090 Mose S transponder is turned off the 1090 ADS-B (Mode ES) stops being transmitted. If there is a 1090 ATCRBS or Mode S being transmitted (no 1090 ADS-B) there could be a UAT ADS-B broadcast that is separate. Some avionics packages are linked (ADS-B data packet Mode S 4096 code is matched) and some that are not linked. The Garmin GDL-88 has a mini interrogator that sniffs the 1090 4096 beacon and matches it if received or sets its 4096 beacon code in the UAT data packet to 1200 if no 1090 code is detected. We have to work around that issue at times.

                              Comment


                              • Here's the search area Exadios described:

                                capture_001_20032014_111457.jpg

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