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ADSB Position taken 1st before Radar by ATC

mbert

Active Member
This week I heard an interesting briefing from some of the Dallas Air traffic controllers where they said the ADSB output is their primary aircraft location ?on the scope? when aircraft are ADSB-out equipped; then radar is used for position of the aircraft. I thought this was really interesting as they said eventually radar systems will be turned off just like navaids currently are on the chopping block. So ultimately low traffic radars will be shutdown as ADSB-out becomes more prevalent. I found this interesting because with many of the UAT sniffer set ups it needs to be in a radar environment to display certain pieces of data (squawk, Pressure altitude, etc).

They also had not heard of the anonymous mode option where a random set of characters is displayed instead of tail number when squawking VFR. So I?m not really sure how that is displayed on their screens...they suggested just calling up when in radar and asking what was showing up on the controllers screen.
 
I fly a non engine-driven electrical system Luscombe that cannot support ADS-B due to the "always on" requirement. This aircraft and similar non-electrical aircraft have an ADS-B exemption for areas below rule airspace and within the legacy Mode C veil. So we can traverse VFR corridors under Class B w/o equipping. I guess eliminating radar means that these aircraft will be more than just anonymous. They will be invisible. I wonder if Jeff Bezos will refund my Amazon Prime membership if one of his cappacino-delivering drones takes me.down.
 
I fly a non engine-driven electrical system Luscombe that cannot support ADS-B due to the "always on" requirement. This aircraft and similar non-electrical aircraft have an ADS-B exemption

https://www.ecfr.gov/cgi-bin/text-i...66e318c1f474d81b&node=se14.2.91_1225&rgn=div8
"(e) The requirements of paragraph (b) of this section do not apply to any aircraft that was not originally certificated with an electrical system, or that has not subsequently been certified with such a system installed, including balloons and gliders"

My interpretation (IANAL) is that this applies as long as you don't have an STC for an electrical system (for example for a starter, lights, or a radio.) There is no exemption for having an electrical system but not having a charger for your electrical system on-board. I'm not entirely sure where the line is drawn but I suspect it is around the time you install a battery and wiring. But again IANAL.
 
When the use of the term ?electrical system? came into play when transponders were mandated, the NPRM defined it as an aircraft with a generator capable of supplying power to the aircraft and for recharging the battery. The same definition applies as the term is used with respect to ADS-B.
 
The original rule for Mode C exempted ?any aircraft which was not originally certificated with an engine-driven electrical system or which has not subsequently been certified with such a system installed...?

The ADS-b requirement dropped the ?engine driven? part of the rule, but the FAA has since ruled that the same aircraft are exempt.

We had a wind driven generator on our L-4, and a call to the FSDO confirmed it was still exempt since it was not engine driven.
 
... the ADSB output is their primary aircraft location ?on the scope? when aircraft are ADSB-out equipped.
That's interesting because several months ago my Mode-C failed while I was within a Class C. I asked the controller if he couldn't just use my ADS-B for my altitude and he said, "No". So maybe they can use ADS-B for lat/lon but not altitude?
 
That's interesting because several months ago my Mode-C failed while I was within a Class C. I asked the controller if he couldn't just use my ADS-B for my altitude and he said, "No". So maybe they can use ADS-B for lat/lon but not altitude?

Or maybe different ATC facilities have different timetables for adopting the new technology?
 
Or maybe different ATC facilities have different timetables for adopting the new technology?
Very true. I do know that the radar room at AVL has the new "Fusion" system, which supposedly displays ADS-B as well at radar from nearby areas (Greer, ZATL). I suspect the problem is that GPS altitude can be several hundred feet different than pressure altitude and they don't have an automatic system yet to correct for that. I've been meaning to go up there for a tutorial, but haven't done so yet. I've been flying with ADS-B (out) for nearly two years now and freely admit that I don't understand all I know about this subject (wink).
 
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I suspect the problem is that GPS altitude can be several hundred feet different than pressure altitude and they don't have an automatic system yet to correct for that.
).

??? ADSB is supposed to output pressure altitude.
Like the OP, I don?t understand how any ?sniffer? system will work if radar is disccontinued.
 
??? ADSB is supposed to output pressure altitude.
Like I said, there's a lot about ADS-B that I still don't understand. So I had to look it up. Apparently, ADS-B broadcasts both pressure altitude (from your transponder/encoder) and geometric altitude (from your WAAS GPS). This is what the FAA says about it: Frequently Asked Questions (FAQs)
ADS-B reports two kinds of altitudes: barometric and geometric. Barometric or pressure altitude is the one pilots know best – this is the altitude that is displayed on the altimeter in the aircraft. Geometric altitude is calculated by GPS (Global Positioning Satellites) as the height of the aircraft above the earth ellipsoid. These two altitudes are not the same, but having both allows for applications that require one or the other as an altitude source and provides a means of verifying correct pressure altitude reporting from aircraft.
I have no idea if ATC has the option of viewing GPS altitude on their screens.
 
FAA RADAR Shutdown

...I guess eliminating radar means that these aircraft will be more than just anonymous. They will be invisible.

Not so fast. From what I've read Congress has mandated that FAA, DoD, etc. will vacate the 1300-1350 mhz. and the bandwidth will be auctioned off to pay for replacement sensors to fill that "L-Band" gap. The program is called SENSR, and you can find more about it on the FAA webpage: "https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=22634"

Doug Lomheim
RV-9A 13B/FWF
RV-3A restored / flown / sold
 
Not so fast. From what I've read Congress has mandated that FAA, DoD, etc. will vacate the 1300-1350 mhz. and the bandwidth will be auctioned off to pay for replacement sensors to fill that "L-Band" gap. The program is called SENSR, and you can find more about it on the FAA webpage: "https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=22634"

Doug Lomheim
RV-9A 13B/FWF
RV-3A restored / flown / sold
Although capable of operating around 1330Mhz, most DOD "L-Band" radars operate around 1270Mhz so this would not affect them.

:cool:
 
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Someone here brought up an interesting subject; if radar is eventually turned off, then someone without ADSB can penetrate the class without them knowing they are there? You know someone will do it.
True or not
 
Someone here brought up an interesting subject; if radar is eventually turned off, then someone without ADSB can penetrate the class without them knowing they are there? You know someone will do it.
True or not
I can't believe this misinformation is still being repeated.

There are two different RADAR systems in the US. The one looking for terrorist and foreign militaries (long range search RADAR's) are funded/owned by the DOD and it is being upgraded as we speak. The DOD shares this RADAR data with the FAA (Center radar data) and US Law Enforcement. There has never been any talk about eliminating or even reducing it.

The other one (short range approach RADAR's) are funded/owned by the FAA and can easily be replaced with ADS-B data.

:cool:
 
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