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Discussion in 'Flight Following' started by John Collins, Jan 25, 2014.
What do the towers look like? Just normal radio towers?
Most are just on existing microwave towers used by AT&T. New ones at airports look like a simple tower with alternating white and red paint. The antennas are on the top and the equipment is in a fenced in area with a backup power system.
The loran shutdown was a political decision, not a financial decision. The Commandant must have had his fingers crossed when he signed the papers.
Enhanced loran is coming back....other nations are already using it and our government can't ignore the GPS backup consideration much longer.
Bob Gardner (CO of two loran stations)
Thanks for the complete directions, John. We hope to be out there in a few months, altho' that may be too late to make much of a contribution to your project.
John, just wondering, if the lat/long was in the wrong format in a user's screenshot, why not just do the conversion?
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I locate the tower using Google earth to confirm its location. It is my intention to use it for mapping. With the default format dd mm, I can't find the tower to confirm that it is correct. I found many errors in entry using this confirmation step as I enter the value and no tower is at that location. I also use the latitude to sort the location of the towers and to check for duplicates. So far, I have yet to find two towers with the same exact latitude when using it as the first sort in the format dd mm ss. I can convert from the format dd.mmm as it has the accuracy, but it is more work, so I have asked to have the latitude and longitude in the same format.
This is the tower at Glasgow, Montana.
When I saw the .kml suffix i thought, o poop, i can't use that file. but downloaded it anyway. WOW it opens with Google Earth no problem, exactly what I've been looking for! Thank you SO very much, Mr Collins!
You are welcome, if you have ForeFlight, you can also download the .kml file as a set of user waypoints. Up to 536 so far. still looking for more.
Any updates on exact tower locations now that all of them supposedly have been installed?
I did not know that. Of course FF also plots any towers you're receiving via any compatible ADS-B receiver and puts a tower icon there by whatever lat/long it's transmitting. With both layers turned on, you'd be able to see clearly if a particular tower wasn't in the kml file. But I don't know how you'd tell FF to plot all user waypoints simultaneously.
ForeFlight will plot the locations of user waypoints by turning on the user waypoint layer. I use the technique you describe to locate towers that are not in the database. I am up to 557 out of 634 the FAA claims. Thru a FOIA case, I expect to get all of the locations this year. FOIA has already ordered it, waiting on final adjudication.
Neat use of FOIA. Hopefully they don't decide you can't know because you're a "terrorist". Even though they all broadcast their location. LOL!
I still don't see where to turn on that whole "layer" at once but I'll take your word for it.
I've used your KML to find the closest tower and it's dead on. Complete with dead end dirt road to the site, and it's a tower site I didn't even know was tucked back in there on the ridge headed out toward my house.
See attached screenshot
Huh. I guess I never realized it was a selection in that menu. I've always used them by typing the name I gave them into the route. Have a bunch of mountain passes marked, stuff like that.
John, is there any way to determine which of the towers transmit CONUS radar?
There are four tiers of tower types. High, Medium, Low, and Surface. The High and Medium provide the CONUS NEXRAD product. On ForeFlight, you can display the towers if you have a compatible ADS-B In receiver. They are labeled High, Med, or Low. See the screenshot.
John, very cool! So the towers transmit their associated type in the messages and Foreflight displays it! Then it might be cool for the type to be added to your tower list? Tks v m for explaining!
Our government would rather spend bundles of money finding other technological means of dealing with the issue.
Thanks for all you've done on this subject.
As to a backup for ADS-B, as I understand it, the FAA's existing radar system is supposed to be the backup today, and probably for a long time. Originally, radar was supposed to go away, in order for the FAA to save money, but it can't since TCAS systems use it... which is also why we can't get rid of our Mode C transponders.
Is there an updated tower map? Everyone I see is still dated like 2014 or earlier.
I do not have Foreflight
Radar was never intended to go away, that is an urban pilot legend. Read the original NRPM and the final rule. Radar was always intended as the backup. 100% of the enroute secondary radars for above 18,000, and 100% of the primary radar systems were always to be kept. About 50% of the secondary radars were to be kept, but this number is likely to be higher. This is detailed in the final rule. Also, the final rule determined that staying with the existing radar system was the least costly option but it did not provide the accuracy available using ADS-B. TCAS depends on transponders, so they were always part of the plan as well.
Thanks for that information John.
As I see it, the FAA is helping to perpetuate the idea that Mode C transponders will go away. Maybe. Someday. Here is the FAA's FAQ on the subject:
"Will Mode C transponders be required indefinitely?
The FAA is considering additional changes in the national airspace system, such as for TCAS. These changes, may at some future date, reduce or eliminate the need for transponder equipage."
But, given what you say... that radar and our transponders are here to stay as the long-term backup solution, then it makes me think that a UAT solution for my airplanes is probably not a good choice, since maintenance on my older (still required for a long time) Mode C transponders will kill any advantage over simply getting a new 1090ES transponder right now.
An update. My KML file with the GBT tower locations is now up to date with the latest information I received via FOIA requesting the locations. Unfortunately, the FAA did not provide the data I requested to the nearest degree, minute, second of latitude and longitude, they provided only to the nearest hundredth of a degree and in many cases not that accurate. I added the 100 locations that were new to me using the FAA designated identifiers with an appended underscore so they would not conflict with airport waypoints in the database. So if the tower user waypoint ends in an underscore, for example EYW for Key West, I coded it as EYW_.
If you are able to use ForeFlight and display the actual position on one of the towers with the underscore and provide it to me, I will update the database and rename it to EYW- instead of EYW_. That way once it is reported, if you do an update of the KML from my link https://dl.dropboxusercontent.com/u/589 ... points.kml , you will be able to distinguish it as being accurate or the FAA rough value.
I have also attach a list of the GBT that are new to me and less precise. They are organized by state, so if you are in the area, please use it to help determine the ones I am still looking for improved data for.
So where did Foreflight get the data if not the govt?
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I would provide the data to ForeFlight, but it is mine and the vast majority of the data is based on pilot reports to me using features of ForeFlight. Of course it is the FAA's GBT that broadcasts the data and in the 100 cases where no-one was able to provide the locations, the FAA provided it via an FOIA request.
No I mean Foreflight already displays ADSB tower locations, if you can't get the info from the government how did they? (Evidently)
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The GBT ground stations broadcast their latitude and longitude continuously. Most EFB apps display the location of those being received on the map view, but ForeFlight also allows the latitude and longitude value of the stations being currently received to be displayed. It is thru the latter capability pilots took screenshots and sent to me and I recorded them in my database. I got about 550 through that means, but there were more and I requested the locations from the FAA via a FOIA. Since the towers transmit their positions, it is not a secrete, but without the FAA being forced to provide the data, they were unwilling to do so.
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Happy Thanksgiving to you,
Has anyone had positive contact with Ohio ADS-B towers OH011 (east of KOSU) or OH007 (east of Defiance Ohio KDFI)? I have been not seen these locations appear on ForeFlight during my flights in North Centeral Ohio and am curious if anyone else has seen these GBTs in operation. Many thanks to John Collins for his contributions to this project.
Does anyone know what happened to the Dropbox kml tower location file? The Dropbox link in this thread appears to be dead.
It is my dropbox and dropbox removed all public links. Here is a current link. https://www.dropbox.com/s/v350zbnxlelowr9/user_waypoints.kml?dl=0
Let me know if that does not work
Hi, John this is a neat work you did there. I gone through your complete posting and lot of useful information, Thanks for sharing this. I basically develop things as part of the ADS-B receivers and display. Wondering if there is a way to determine the Tier Category (High, Med, Low or Surface) of the tower which I am receiving. I do not see this information encoded directly in to the messages. I read the information from industry standards, couldn't understand it clearly though. Do you know anything about that? Also, the look-ahead ranges are nothing but coverage for the weather product? Appreciate your response.
If you make of a google earth *.klz file it will be able to be overlaid in the newer versions of foreflight.
Doesn't mode S end up displaying on the system?
I use ForeFlight to collect the raw data. It includes the tier information. I have not updated the database to include the tier, but it could be done. The tier information is part of the UAT broadcast information from the tower.
See appendix C of the Surveillance and Broadcast Services Description Document You can download a copy at