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  #241  
Old 01-10-2017, 09:24 PM
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dpansier dpansier is offline
 
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When the Radar sites are decommissioned, what safeguards are built into the system to prevent someone from transmitting a signal on 978 MHZ with the proper protocol and fake Lat / Lon / altitude?
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  #242  
Old 01-10-2017, 09:56 PM
Kyle Boatright Kyle Boatright is online now
 
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Quote:
Originally Posted by dpansier View Post
When the Radar sites are decommissioned, what safeguards are built into the system to prevent someone from transmitting a signal on 978 MHZ with the proper protocol and fake Lat / Lon / altitude?
Nothing. There's nothing to prevent that now. It would just confuse things. That's one of the vulnerabilities of ADSB - no effort was made to prevent spoofing.

As for Radar, 9/11 pretty much put to bed the idea of completely eliminating it.
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  #243  
Old 01-10-2017, 11:01 PM
BobTurner BobTurner is offline
 
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Originally Posted by dtw_rv6 View Post
What happens to transponders on that day? Without radar, there will be nothing to interrogate them.... How will we set a squawk code, and even further, why would we need to?
Don't worry, Big Brother I mean the FAA has thought about this. The backup to an ADSB failure will be TCAS (transponder based collision avoidance) which the airlines already have. So we'll be required to have transponders even after radar goes away, so airliners can see us in an ADSB failure. GA? The FAA doesn't really care.
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  #244  
Old 01-10-2017, 11:45 PM
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az_gila az_gila is offline
 
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Originally Posted by MartySantic View Post
I was under the impression that the initiation of an ADS-B out transmission packet required a ping from ATC. As opposed to an asynchronous mode where the ADS-B out transmission is made at an interval. Yes/No??
The 1090 ES (Extended Squitter) transponders will "squit" without an ATC radar contact.

If you?ve ever flown with a Mode S transponder, you?ve already done your fair share of ?squittering.? By definition, the word ?squitter? refers to a periodic burst or broadcast of aircraft-tracking data that is transmitted periodically by a Mode S transponder without interrogation from controller?s radar. Mode S ( which stands for mode ?select?) technology was first developed in the mid-1970s as a way of using existing ground-based secondary surveillance radar (or SSR) to track onboard transponders more precisely and more efficiently ? while reducing the number of interrogations required to identify and follow aircraft on the controller?s radar scope.

Good operation description from Garmin here -

http://www.garmin.com/us/intheair/ads-b/squit/
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  #245  
Old 01-11-2017, 07:35 AM
dtw_rv6 dtw_rv6 is offline
 
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Does mode S interrogate my Mode C transponder? Sounds like older transponders aren't visible to TCAS.
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  #246  
Old 01-11-2017, 07:47 AM
David-aviator David-aviator is offline
 
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Quote:
Originally Posted by Kyle Boatright View Post
Nothing. There's nothing to prevent that now. It would just confuse things. That's one of the vulnerabilities of ADSB - no effort was made to prevent spoofing.

As for Radar, 9/11 pretty much put to bed the idea of completely eliminating it.
One of my brothers, retired Navy electronics specialist, worked on FAA radar systems through his employer after transition to civilian life. He said the system was very complex in that newer radar computers were layered on top of old. At the time he said original computers, based on first iMac platform, were still being used 20 years after introduction.

The system certainly was prone to failure, not often reported to public. I was working a trip from Boston one morning when advised by NY Center to proceed to a VOR in New Jersey and hold indefinitely. Ok. what's going on? Answer, we just lost all radar.

I called dispatch and advised and they responded land at PHL. I responded, descent through 35,000' of uncontrolled airspace? Not a good idea. How 'bout we just proceed west at 350 until we get to Cleveland airspace and reestablish radar contact. About then NY called and said they got it working, cleared as filed.

There will be ADS-B failures also. My guess radar will be around a long time, old as it is, as a back up.

The cost of all this might have gone long way to whole new radar system, we will never know.
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  #247  
Old 01-11-2017, 11:49 AM
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GalinHdz GalinHdz is offline
 
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Quote:
Originally Posted by dpansier View Post
When the Radar sites are decommissioned, what safeguards are built into the system to prevent someone from transmitting a signal on 978 MHZ with the proper protocol and fake Lat / Lon / altitude?
FWIW: The long range center radars (although maintained by the FAA they are owned and funded by the DOD) are not, have not nor has anybody even talked about them being decommissioned. Think NORAD and air defense. Now short range approach radars (maintained, owned and funded by the FAA) are a different animal.
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Last edited by GalinHdz : 01-11-2017 at 03:01 PM.
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  #248  
Old 01-11-2017, 01:08 PM
Jordan1976 Jordan1976 is offline
 
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Quote:
Originally Posted by dpansier View Post
When the Radar sites are decommissioned, what safeguards are built into the system to prevent someone from transmitting a signal on 978 MHZ with the proper protocol and fake Lat / Lon / altitude?
Multilateration can be used to both back up certain ADS-B system failures, as well as provide detection of signals which originate from a different physical location than the payload indicates. Multiple ground stations or a ground station and a satellite can be used for multilateration.
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  #249  
Old 01-11-2017, 06:03 PM
Swoda Swoda is offline
 
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Default FAA NAVWORX FOIA REQUEST

Answer from the FAA on a FOIA request submitted on NAVWORX NPRM seeking the documents the FAA used to decide to issue an AD.

I had no part in the FOIA request, just passing it on.

https://drive.google.com/file/d/0B0F...pwYmFXQ2s/view
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  #250  
Old 01-11-2017, 06:50 PM
DennisRhodes DennisRhodes is online now
 
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My that was pretty much a waste of server space!!! About the only bit of knowledge there, and I already knew this, was that the FAA looks at all threads on the Vansairforce site. Remember the S in ADS B stands for surveillance.
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