Feedback on ADS-B tower locations

Discussion in 'Flight Following' started by John Collins, Jan 25, 2014.

  1. John Collins

    John Collins Pattern Altitude

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    I have been collecting the locations of ADS-B GBT (Ground Based Transceiver) locations. I tried to get this information from the FAA, but they declined. So I have been crowd sourcing the information from pilots who have the ForeFlight App and a Stratus ADS-B receiver. They are able to display the latitude and longitude of all GBT locations being received at the time and have provided me with screen shots that I enter into my ForeFlight iPad as user waypoints. Other applications and ADS-B receivers are capable of providing this information, but so far, only ForeFlight provides an actual position of the stations. Pretty much all of the applications provide a graphic presentation as does ForeFlight, but this doesn't lend itself to determining the locations, so I have only used ForeFlight for this purpose.

    As of this post, I have collected the locations of 459 GBT stations. All of these are now saved in a file that I am now sharing with others. The file can be downloaded and if you click on it, it will open Google earth and show the locations. Also, the file can be downloaded to ForeFlight as a collection of user waypoints. Since I don't yet have all the roughly 800 planned stations, it is helpful for those who have ForeFlight to know which ones I have already been provided and to identify new stations that can be added to the collection. Previously, the pilot had to periodically do a screen shot of the station locations and email that to me. I then had to determine if any were new or not and add just the new ones. This should make it easy for a pilot to see a new station that isn't included and send it to me.

    If you wish to send me screenshots from ForeFlight, please send them to my email at john.collins52@yahoo.com. Also, please please please please change the ForeFlight setting for displaying latitude/longitude from the default setting of DD.dd to DD MM SS, otherwise I won't be able to plot them.

    The instructions for downloading the file https://dl.dropboxusercontent.com/u/58910037/user_waypoints.kml to ForeFlight are found at http://www.foreflight.com/support/user-waypoints

    The name of the waypoints is of my own invention, except for Alaska where I used the FAA names. For the names in the CONUS, I used the following conventions:

    1) If the GBT was not located at an airport, I used the two character state identifier followed by a sequential three digit number, so NC001 is the first one I recorded in North Carolina and NC005 is the fifth one I recorded. Florida was an exception because ForeFlight treated FL as Flight Level, so I used FLA followed by a two digit number.

    2) If the GBT was located at an airport, I used the ICAO code for the airport eliminating the leading K and adding a two digit number starting at 00. The reason I did this was that some of the larger airports have two to four GBT locations and I needed to use a user waypoint identifier that would not conflict with the ICAO identifier. If the airport was of the three character variety, I used the airport ID with a letter A appended to the name for the same reason, to distinguish it from the airport.


    Even if you don't have ForeFlight, you can view the locations using Google earth by downloading the file and clicking on the download. Here is a screenshot from my computer for the locations I have collected.

    My 458 GBT locations as of 1-25-2014.jpg
     
    Last edited: Jan 25, 2014
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  2. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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  3. John Collins

    John Collins Pattern Altitude

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    Did you download them to ForeFlight?
     
  4. Jaybird180

    Jaybird180 Final Approach

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    Forgive my obtusivity, (smile), but what is the practical application of this information.
    Also, please theorize on the justification the FAA didn't disclose.
     
  5. CT Arrow

    CT Arrow Line Up and Wait

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    Last edited: Feb 13, 2014
  6. John Collins

    John Collins Pattern Altitude

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    If you have Google earth installed, all you need to do is click on the file and Google earth will open with the locations as named stick points.
     
  7. John Collins

    John Collins Pattern Altitude

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    The answer I got was that it was sensitive data. The fact that each GBT broadcasts its exact position and that I could collect this information freely didn't seem to make a difference. I obtained a list of the locations for the Alaska from a public FAA document that must not have gotten the message.

    There are two primary uses of the data. Knowing where the GBT stations are located, one can determine before or in flight where services can be expected. I have used this capability to determine in advance of a flight that services would be available on the ground at my destination. In this particular case, the tower was located on a mountain top with line of sight to the airport. In other cases, the airport has a tower located on the property. The second use is that one can determine if a route can be expected to have services at the planned altitude. This is more meaningful in the mountains where coverage is not as complete, particularly at lower altitudes.

    A secondary reason is that most iPad applications (ForeFlight, WingX, Garmin Pilot, and others) display graphically the GBT locations that are being received. If one that should be received but isn't, knowing where it should be can aid the pilot in troubleshooting his own installation or antenna location or provide a pilot report that a station is OOS.

    Since I am collecting this data to provide a complete set, it helps those pilots who are crowd sourcing this data to determine if the GBT has already been reported or is worth capturing the data. They send me the screen shots and I update the file.

    Not every pilot will find this data useful and will not bother with it. I am providing the data free of charge and without restrictions. Anyone not interested can ignore the post and not download the file, no harm done. Most of the tower locations are already charted on the sectional as obstacles and included in obstacle databases. They just don't indicate the use of the tower. It is like everything else, some will be interested in this data, others will not. In my case, seeing the location and frequency of NDB stations on the sectional is of no use to me, my ADF was removed from my airplane 14 years ago.
     
  8. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    No, not yet - I've been using the built-in display on ForeFlight in flight, I may use these pre-flight.
     
  9. aterpster

    aterpster Pattern Altitude

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    The FAA used to make available to the public the location of all ARTCC radars, whether ARSR, or beacon interrogator. Then, about three years ago those data were removed from the FAA's public data systems.

    My group made an inquiry. We were told those locations had suddenly been deemed too sensitive for the public to know. Further, we were advised that a FOIA request would almost certainly be denied based on national security reasons.

    So, I made the FOIA request and it was granted without reservation. Shortly after that the FAA once again posted the names and locations on a different public website.

    "Government inaction" is two words, not three. :rolleyes:
     
  10. dell30rb

    dell30rb Final Approach

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    Thanks John, cool project. I think I know of one or two locally that might not be on your map. I'll be sure to grab a screenshot next time and send it to you.

    Does anyone know the approximate range of an ADS-B station? Curious if I will get service in the Bahamas at 5-7000 feet or so. Probably 100NM from the nearest ADS-B station.
     
  11. John Collins

    John Collins Pattern Altitude

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    If a tower was on the coast and at an elevation of 50 feet, you would need to be over 9000 MSL to receive the signal by line of sight. There are three tiers of towers, with low power, medium power and high power. The medium power ones are intended to support up to 14000 MSL and the High ones up to 24000 MSL. So if you are at 9000 + feet you might be able to receive either a medium or high tier tower. Your antenna location would also matter as it might be blocked by your fuselage. Best results would be from a bottom mounted external antenna.
     
  12. akpilot907

    akpilot907 Pre-takeoff checklist

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    That's really neat... although they have no help to me... It's neat to see where they are... might take a drive out to the nearest one and take a lookie!
     
  13. jhlindsay

    jhlindsay Filing Flight Plan

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    John: Can you tell me where FL05 is in relationship the nearest airport? Thanks much, Giz
     
  14. jhlindsay

    jhlindsay Filing Flight Plan

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    John: Sorry, I meant FLA05. Thanks again, Giz
     
  15. ARFlyer

    ARFlyer En-Route

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    Thanks for the file and information. I've been wanting to make Line-of-Sight maps for myself.

    I can now correlated the locations to FCC tower records.
     
  16. John Collins

    John Collins Pattern Altitude

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    2014-06-24 07.07.00.png
     
  17. John Collins

    John Collins Pattern Altitude

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    I still need some help on the GBT locations in south Florida down to the keys.
     
  18. John Collins

    John Collins Pattern Altitude

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    Anybody in Montana, I could use help in the area, there are several new locations that I don't have recorded as of yet.
     
  19. Dr. O

    Dr. O Pattern Altitude

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    Pardon me while I have a tantrum:
    So the government could not AFFORD to keep a dozen Loran towers running, but we can afford 450+ and growing towers for this. (primal scream)
     
  20. John Collins

    John Collins Pattern Altitude

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    Over 634. Can I hear you now? :rolleyes2:
     
  21. AuntPeggy

    AuntPeggy Final Approach

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    I went to a Garmin seminar a week or so ago where they were talking about ADS-B. Among the things we learned is that ADS-B is being installed on existing cell phone towers and looks a lot like a cell phone transmitter/receiver. So, the cost to the government in installing ADS-B is significantly less than any previous installation, such as LORAN or VORs. They are probably just renting a slot on someone else's tower.
     
  22. John Collins

    John Collins Pattern Altitude

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    True. Also the contract with ITT Exelis is for a fixed amount and regardless of whether they had to add a tower as they often did at airports or use an existing cell tower is irrelevant to the taxpayer as it is the contractors expense.
     
  23. Pedals2Paddles

    Pedals2Paddles Cleared for Takeoff

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    Thanks for this! I've been looking for this information for my area and viola. There's a ground tower at my field and all around me. Yay.
     
  24. CTLSi

    CTLSi Ejection Handle Pulled

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  25. John Collins

    John Collins Pattern Altitude

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    Anyone can find the coverage maps, but they are very crude and don't tell the pilot if they can expect to receive one, particularly if they are at an airport. IMHO they should be charted on the sectionals.
     
  26. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    The page CTLSi linked to has a excel spreadsheet list of stations and what airports they are at. Not Lat/Lon mind you but it tells you roughly where it is.
     
  27. John Collins

    John Collins Pattern Altitude

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    Very roughly. I requested the latitude and longitudes from the FAA but was denied due to the data being sensitive. I have supported an open issue at the ACF to include these locations on the sectionals. For the most part, they already are on the sectionals as obstacles, but they are not identified. There is an exception, on the Helicopter charts in the Gulf Coast area, they are marked on those charts. I have collected the precise locations of over 500 of the GBT, but am still about a 150 short, mostly in the Montana, Idaho, Utah areas. I download them to my ForeFlight as user waypoints and can see what is near my position or at least what should be easily received. The application also displays the towers it is receiving and if I have a user waypoint at the same location of the tower, I know I already have it in my list. If there is just a tower, I know it is new to me and I record the Latitude and Longitude (which is broadcast by the tower) via a screen shot.

    My list is also downloadable as a KML file and if you click on it, it will show the locations on Google Earth.
     
  28. Sierra Victor

    Sierra Victor Pre-Flight

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    Thank you very much for this!!
    I am having a GDL 88 installed at this very moment and have exhaustively searched for a map of GBTs to get a sense of what and where services are available. The map that Garmin provides is very ambiguous and the map on the NextGen site is now outdated. It shows only one station in ID and none in UT, whereas yours shows that has changed.
    I understand the pushback from pilots regarding cost of equipment but the ADS-B system is an enormous leap forward in the modernization of GA!! Ten years from now we'll take it for granted.
     
  29. John Collins

    John Collins Pattern Altitude

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    If you have a Stratus and ForeFlight, I would appreciate it if you discover any new GBT locations and I will add them.
     
  30. Sierra Victor

    Sierra Victor Pre-Flight

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    I have Foreflight but no Stratus. Any way to get GBT locations on a 750?
    Also, I'm confused about reception. Can you explain the broadcast range and do you know which tower is capable of which strength/distance of signal? For example, in southern ID where there are only a couple of towers, what would you expect for reception coverage?
    Also, on average, how many towers are you seeing added per month and do you think they intend to provide relatively thorough coverage in the Rockies?
     
  31. John Collins

    John Collins Pattern Altitude

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    My understanding is that the initial contract installations are all completed. You need line of sight in order to receive the GBT, so a mountain will interfere if it is between you and the GBT. at 9000 MSL, line of sight to the natural horizon is about 100 NM and at about 4500 feet, the horizon is about 70 NM away.
     
  32. denverpilot

    denverpilot Taxi to Parking

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    Isn't it nifty that you can easily get the home address of every pilot in the country , even against the Congressional mandate to stop that...

    But knowing where an antenna, box, and telephone pole is, is "too sensitive"?

    ROFL.
     
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  33. CTLSi

    CTLSi Ejection Handle Pulled

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    I have Dynon Skyviews, Mode S Transponder, ADS-B and a Garmin 796/WAAS. I have ADS-B in and out, and TIS-B.

    I get ADS=B weather and data everywhere I fly, even down the middle of Nevada.

    You may not get it in North Dakota, but you will get it virtually everywhere else...esp all over the East coast, South, and California.
     
  34. Badger

    Badger Pattern Altitude

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    There is one at W19, a very small private grass strip with 3 planes based there that rarely fly:however 15 miles away at class C KMSN, they don't have one, so no info while on the ground. Makes no sense to me. Probably money behind the location decesions.

    Sent from my SCH-R970 using Tapatalk
     
  35. John Collins

    John Collins Pattern Altitude

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    To make matters worse, the GBT broadcasts its position in the clear.
     
  36. Marauder

    Marauder Cleared for Takeoff

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    I suspect that the majority of the secrecy is over the security as they move to the NexGen environment. If the network becomes compromised by a malicious act, the air traffic system would be at risk if it is the backbone of the new system. I wouldn't be surprised to see additional security placed on them in the future.

    When GPS rolled out, it was not intended for civilian usage. The signals could be scrambled by the military at will. There was less risk of someone intentionally taking out the 24 satellites but I do remember security concerns about greater access.

    John -- by now you are probably on some NSA/TSA/FBI or Homeland Security list. ;)
     
  37. John Collins

    John Collins Pattern Altitude

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    I seriously doubt they could sustain a FOI request. The same was done regarding the radar sites, they used to available publicly, then the government said they were sensitive and no longer provided them. NBAA forced them to provide them once again with a FOI.
     
  38. Marauder

    Marauder Cleared for Takeoff

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    I suspect like BARR and other FOIA requests, it will go through the usual due process and a list will be provided. The concern may be as simple as the nature of these antenna (public access is easier).

    Is your quest to just map them or to understand the service volumes they would provide?
     
  39. CTLSi

    CTLSi Ejection Handle Pulled

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    There is nothing secret about ADS-B...in fact it's a mandate. Wow the paranoia lately...must be Obama...
     
  40. John Collins

    John Collins Pattern Altitude

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    What I would like to do is to map them, both on the sectional charts and on my ForeFlight. I am at the 75+% point having accomplished the later. I use them to plan flights and in some cases choose where I land. I eventually plan on being able to determine which stations are working and providing services and report outages.