Things on my map that I don't understand

FlightAware ADS-B Flight Tracking
1

Let me first apologize if these questions are answered in a FAQ somewhere; I’ve been looking for several hours over a couple days and just am not finding it. I’d love to be directed to a FAQ with this stuff. These are all things I see on my map page and they puzzle me.

  1. In the FLIGHT column what is meant by “???”
  2. In the FLIGHT column what is meant by random numbers like “381” or “5888”?
  3. Why do the blue A/C icons seem to rarely show a white flight number block on mouse-over when the grey ones nearly always do?
  4. Why do the A/C icons sometimes show a complete data block beneath continuously and other times have no data shown without mouse-over, and then only the flight number and ICAO code not the full data?
  5. What does the number in the SEEN column mean?
  6. I’ve repeatedly seen reference to making adjustments through a + symbol in the upper right of the map. There is no such symbol on my map.
  7. What’s up with the Settings ] link on the map under the UTC clock?
  8. On the two clocks what is the purpose of the size-changing blue shading under the second hand?

Thanks for all your help!
Larry

2

Could you provide what map you are seeing these items on?

3

Here it is:

http://tinypic.com/m/j10gpj/2
Thanks

4

  1. In the FLIGHT column what is meant by “???”
    The Flight column is usually the tail number or the Flight Number. Tail numbers usually start with the country code for the USA which is “N”. Flight numbers is what a traveler usually sees on their ticket. It can either just be the Flight number or the Airline code + flight number (Like JBU490 in your screen capture for Jet Blue 490). Sometimes the plane transmits a Flight number and other times we get the information from a database. If you want more information on a plane you can look up the ICAO hex code (first column) on flightaware.com

  2. In the FLIGHT column what is meant by random numbers like “381” or “5888”?
    These are Flight numbers. It is the number a passenger will see on a ticket. You need an Airline + Flight number to identify the actual airplane. See #1 for more info.

  3. Why do the blue A/C icons seem to rarely show a white flight number block on mouse-over when the grey ones nearly always do?
    Blue are the old transponders with MLAT fix. They only transmit ICAO, altitude. They never transmit flight number. We know the position because of MLAT.
    The white row are the old transponders that we don’t have an MLAT fix on. They also never transmit flight numbers or other information.
    The green row with all the columns filled in are the new ADSB transponders.

  4. Why do the A/C icons sometimes show a complete data block beneath continuously and other times have no data shown without mouse-over, and then only the flight number and ICAO code not the full data?
    See #3 for information about the old and new transponders.

Planes with low message and high seen numbers are not tracking well. If the plane is an ADSB plane then it might take a few more seconds for the row to fill out.

  1. What does the number in the SEEN column mean?
    This is the number of seconds since your receiver has seen a message from that plane. Planes are suppose to transmit about a message a second or less. So if you see it start to climb higher than 0 then you are getting spotty messages. After 60 seconds of not being seen the plane is considered gone and will be removed from the list.

  2. I’ve repeatedly seen reference to making adjustments through a + symbol in the upper right of the map. There is no such symbol on my map.
    There are many version of dump1090. PiAware doesn’t have a + symbol.

  3. What’s up with the Settings ] link on the map under the UTC clock?
    The settings button doesn’t do anything at the moment. You can adjust settings through the command line.

  4. On the two clocks what is the purpose of the size-changing blue shading under the second hand?
    That looks like a graphic bug. It doesn’t happen on my system. Which browser and OS are you using to view the PiAware interface? Do you see the same thing on another browser?

5

Thanks David,

  1. I was thinking of the occasions when the FLIGHT column actually displays “???” as a couple do in the map pic. I am very familiar with tail numbers and flight numbers and ICAO numbers but I thought if any signal was received it would include one of those three. But maybe not since sometimes the “???” is there.

  2. How odd that the flight # would be there without the carrier info.

I’ll think about the other points and continue my responses later.

6

It is strange, but I guess depends on company policy or the pilot. This would be what is input in the FMS/front end of the transponder, so it is at the discretion of the pilot.

7

In Europe it is set correctly quite consistently - I think there is an ATC requirement here.
In the US it doesn’t seem to be reliable at all.

8

[quote=“david.baker”]1. In the FLIGHT column what is meant by “???”

The Flight column is usually the tail number or the Flight Number. Tail numbers usually start with the country code for the USA which is “N”. Flight numbers is what a traveler usually sees on their ticket. It can either just be the Flight number or the Airline code + flight number (Like JBU490 in your screen capture for Jet Blue 490). Sometimes the plane transmits a Flight number and other times we get the information from a database. If you want more information on a plane you can look up the ICAO hex code (first column) on flightaware.com
I was thinking of the occasions when the FLIGHT column actually displays “???” as a couple do in the map pic. I am very familiar with tail numbers and flight numbers and ICAO numbers but I thought if any signal was received it would include one of those three. But maybe not since sometimes the “???” is there.

  1. In the FLIGHT column what is meant by random numbers like “381” or “5888”?

These are Flight numbers. It is the number a passenger will see on a ticket. You need an Airline + Flight number to identify the actual airplane. See #1 for more info.
How odd that the flight # would be there without the carrier name info.

  1. Why do the blue A/C icons seem to rarely show a white flight number block on mouse-over when the grey ones nearly always do?

Blue are the old transponders with MLAT fix. They only transmit ICAO, altitude. They never transmit flight number. We know the position because of MLAT.
The white row are the old transponders that we don’t have an MLAT fix on. They also never transmit flight numbers or other information.
The green row with all the columns filled in are the new ADSB transponders.

Hmmmm… The blue a/c icons on my map usually have no data but other times have the tail number or Flight # (I’m currently watching two blue icons ACA364 and N45N), squalk, everything. Strange.

Is it true that the gray a/c icons always are tied to green lines in the chart and blue a/c icons always are tied to blue lines in the chart?

  1. Why do the A/C icons sometimes show a complete data block beneath continuously and other times have no data shown without mouse-over, and then only the flight number and ICAO code not the full data?

See #3 for information about the old and new transponders.

Actually I haven’t noticed any following data blocks on any a/c icons for a few weeks.

Planes with low message and high seen numbers are not tracking well. If the plane is an ADSB plane then it might take a few more seconds for the row to fill out.

  1. What does the number in the SEEN column mean?

This is the number of seconds since your receiver has seen a message from that plane. Planes are suppose to transmit about a message a second or less. So if you see it start to climb higher than 0 then you are getting spotty messages. After 60 seconds of not being seen the plane is considered gone and will be removed from the list.

  1. I’ve repeatedly seen reference to making adjustments through a + symbol in the upper right of the map. There is no such symbol on my map.

There are many version of dump1090. PiAware doesn’t have a + symbol.

So are those changes also made from the command line? Is there a list of those options somewhere?

  1. What’s up with the Settings ] link on the map under the UTC clock?

The settings button doesn’t do anything at the moment. You can adjust settings through the command line.
Is there a list of those options somewhere?

  1. On the two clocks what is the purpose of the size-changing blue shading under the second hand?

That looks like a graphic bug. It doesn’t happen on my system. Which browser and OS are you using to view the PiAware interface? Do you see the same thing on another browser?
[/quote]

Thanks, David

9

Hmmmm… The blue a/c icons on my map usually have no data but other times have the tail number or Flight # (I’m currently watching two blue icons ACA364 and N45N), squalk, everything. Strange.

These are related.

There are two mechanisms to get the ident:

1090ES ADS-B transponders periodically send identity messages that carry the ident. So for aircraft equipped with full ADS-B you usually get this directly. This is reliable (in the sense that it reflects whatever the transponder was programmed with, and we should hear an identity message regularly). So if you’re getting an ADS-B position you’ll usually also get an ident via this mechanism. You will sometimes also get aircraft that have partial ADS-B so they send the ident, but not positions.

Older transponders carry the ident in a transponder register that is not spontaneously sent. But it can be read out by secondary radar by an explicit Comm-B query. If secondary radar happens to query this and we overhear the reply, we can get the ident. But this is not guaranteed - it requires that there’s something doing the query on 1030MHz at a time when we can hear the reply, which is going to depend a lot on the radar and the timing of the query.

The Comm-B responses are also ambiguous. The radar knows what it is querying so it knows how to interpret the reply. But we don’t see the query at all, just the reply, and the replies can’t unambigously be recognized as that ident register. So it’s a best guess. Sometimes, we will overhear a Comm-B reply that seems to match the ident format, but actually it’s some other register that’s being sent that happens to look similar, so you get a garbage ident like ???.

Sometimes the transponders also just send a garbage ident (e.g. all zeros) if they’re not set up correctly, which can show up as ???.