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  • Bug with planes heading north

    When an aircraft has the heading 0 deg, it shows a question mark on the map, and the speed is zero. A plane heading north, flipping between 359 and 0 deg, keeps switching between an aircraft and a question mark.

  • #2
    I doubt there is much that can be done about that. When ADSB traffic without full squitter information is being sent, the system has to show the missing data as unknown. As a result, the default from receivers is '0' for each record.

    Theres no way of telling if the aircraft is not sending this, or going true magnetic north
    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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    • #3
      The problem is that aircraft with broken transponder are transmitting 0 as direction. So 0 = unknown direction. The problem with aircraft heading north not so big as most aircraft transmit 360 degrees when going north.

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      • #4
        But is the heading the only thing that is used to determine if an aircaft is transmitting valid data? If the heading is zero and the speed is non-zero for instance, then the plane must be going north. Only if every piece of data transmitted is zero should the transponder be out of order.

        The speed does get set to zero in the left menu when a plane goes north, but that must be the Flightradar24 software that does that, because the plane must still be transmitting the correct speed. I fail to see how this cannot be destinguished from a faulty transponder where every piece of data is missing.

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        • #5
          Got an example flight for this phenomenon?

          This is an example of a partial squitter transponder.

          http://www.flightradar24.com/2012-05-03/09:54/PST43

          notice the Speed and Track are 0 (unknown) but the location is not.

          I have also seen another that only sends the altitude every 3rd or 4th packet due to a fault.
          Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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          • #6
            I can't find one at the moment, but I watched a plane flying from Copenhagen to Gothenburg in Sweden, which was due north all the way, and it constantly flipped between 359 and 0 deg, resulting in question mark and the speed being set to zero too.

            They are not flying quite as close to north today, as they are taking off in the opposite direction from CPH airport.
            Last edited by Frank B; 2012-05-04, 07:52.

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            • #7
              Originally posted by Oblivian View Post
              Got an example flight for this phenomenon?

              This is an example of a partial squitter transponder.

              http://www.flightradar24.com/2012-05-03/09:54/PST43

              notice the Speed and Track are 0 (unknown) but the location is not.
              Yes, but that one is not flying north, so it is probably correctly marked.

              I will keep an eye out for a good example.

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              • #8
                Here is one now: http://www.flightradar24.com/DLH1YL

                This one even keeps the correct speed when it goes to heading zero.

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                • #9
                  Ah yes, its as I suspected. When track = 0' Then it is automatically considered 'unknown' (or ? as on map) as it relies on all the information to be populated. Which is why when it reads 1 it appears as known again
                  Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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                  • #10
                    Actually it does populate all data, it is just the software that interprets it wrongly. Zero doesn't mean unknown, it means north. I could understand it if other parameters went to zero, like the speed or altitude for instance, but when there is this ambiguity with the heading, then it should not be used alone to indicate a fault. It should be interpreted as north when all other data are present.
                    Last edited by Frank B; 2012-05-04, 08:28.

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                    • #11
                      you are right. Software/programming error
                      http://forum.flightradar24.com/threa...estion-Mark%29

                      solution: if track and speed = zero then "?"
                      Last edited by Charky; 2012-05-04, 08:46.
                      http://www.liveatc.net/search/?icao=LSGG

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                      • #12
                        We have about 100 feeders upload thousands rows of data every second. It's not possible for us to make a real time analyse of the data coming in. As 0 is mostly used by aircraft with transponder problems we show (?). There are also aircraft with direction 0 and speed =! 0. As I wrote, most aircraft uses 360 when they fly in northern direction so this is not a big issue.

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                        • #13

                          thank you for your answer Mike.
                          you dont need to make an analysis of every uploaded message.
                          You only need to put the correct condition into the code.
                          I try to explain it again.
                          track zero is a valid track. so shouldnt show up as error "?".
                          if speed = zero then plane is at the ground or the message which contains track and speed has not been received.
                          if a plane is flying at fl100 and track and speed = zero then its an error "?".
                          if a plane is flying at fl100 and track is zero and speed not = zero then the track is correct zero.
                          if a plane is flying at fl100 and track not zero and speed is zero then its an error "?"

                          In the old FR24 map it had been corrected for some month's but with the new map layout it was comming back.
                          have fun.
                          http://www.liveatc.net/search/?icao=LSGG

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                          • #14
                            I agree with Charky. It doesn't seem to be that much overhead to do a few simple tests for zero values.

                            It may be that most aircrafts use 360, but it is still a bug for those that don't. And I do actually think it is an issue, because it makes the whole project look substandard, when some data are not displayed correctly.
                            Last edited by Frank B; 2012-05-04, 12:36.

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                            • #15
                              We haven't changed anything in this code from last version of the map and as I wrote, it's not so easy as Charky writes.
                              There are aircraft flying on FL100 with correct speed, and 0 heading. There is no rule or easy way of knowing if 0 is error or north apart from estimating heading from previous positions. Maybe that is something we can look on in the future.

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