ADSB Outtage Hypothetical

Sinistar

Sinistar

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Brad
So lets say just the "who is in who"s puck computation was failed or just not broadcasting any traffic via any ground based transmitters.

Now lets say the only planes flying are commercial airliners or GA planes. And lets say the only GA planes flying all have Garmin 345's configured and running properly. No other planes are up flying. Just a bunch of Garmin 345 planes and commercial planes.

Wouldnt every GA plane up flying see all the other nearby planes flying and often well beyond 50miles if they are up high enough?
 
You do realize two jet aircraft can close 15 miles in 1 minute? That is why no VFR in Class A airspace.
 
Clip4 said:
You do realize two jet aircraft can close 15 miles in 1 minute? That is why no VFR in Class A airspace.
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I do realize that....but what the heck does that have to do with the question? I never mentioned GA planes being right up there with them.

I'll refine the hypothetical. Assume the commercial guys are all up their normal flight levels on IFR plans and all ATC radars are working properly. Lets say half the Garmin 345 GA guys are on IFR plans and all the VFR Garmin 345 guys are honoring VFR cruising altitudes. I hope that helps.

This question isn't about trying to mix commercial and GA in the same airspace, etc. This is only about the "ability" to see other traffic with ADSB-In equipment even though the ground transmitters aren't outputting traffic data.

My understanding is that all of these aircraft will still see each other on their adsb-in equipment...Right? Wrong?
 
So all the 345s are transmitting “out” but the ground unit is t/u, is that what your asking? Will other airborne “in” units be able to see the non-repeated but nearby “out” units?
 
455 Bravo Uniform said:
So all the 345s are transmitting “out” but the ground unit is t/u, is that what your asking? Will other airborne “in” units be able to see the non-repeated but nearby “out” units?
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Exactly :)

In theory they should...right?
 
If you have a receiver that is capable of receiving 1090ES ADS-B Out, it will receive any traffic that is broadcasting ADS-B on 1090 MHz and in line of sight to your antenna. Reception range will vary and in most cases will be over 50 NM. Ground stations are not involved. The guy sitting next to you and talking on his cell phone can be heard distinctly by you without using a cell phone yourself. If the other end of the conversation is on his speaker or the other party is in the same room, you can hear him or her as well.
 
John Collins said:
If you have a receiver that is capable of receiving 1090ES ADS-B Out, it will receive any traffic that is broadcasting ADS-B on 1090 MHz and in line of sight to your antenna. Reception range will vary and in most cases will be over 50 NM. Ground stations are not involved. The guy sitting next to you and talking on his cell phone can be heard distinctly by you without using a cell phone yourself. If the other end of the conversation is on his speaker or the other party is in the same room, you can hear him or her as well.
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Thank you!!! Now it's starting to make sense!

Now what if I take away one more variable. What if there were no ATC radars of any kind running. In other words non of these transponders were being swept by a radar to trigger off a response....would everone still see each other? Do these adsb out transponders still send something periodically if not swept by radar?

Also, I would think the receiving antennae would be on the belly of the plane so it would best receive the adsb ground transmissions..is that right? If so does that position make it hard to directly receive squits from above?
 
I believe in your scenario everyone would see everyone. The GTX 345 is a dual-band unit, so it is speaking 1090 ES just like the airliners are.

Now, if you had a GDL 88 hooked up to a GTX 327, for example, instead of the 345s, then the GA planes and the airliners wouldn't see each other. Different frequencies, which normally require ADS-R (rebroadcast, ground-based) to get the data to the other guys.
 
Sinistar said:
So lets say just the "who is in who"s puck computation was failed or just not broadcasting any traffic via any ground based transmitters.

Wouldnt every GA plane up flying see all the other nearby planes flying and often well beyond 50miles if they are up high enough?
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No. 978 vs 1090 - not every platform translates.

National Security waivers - some agencies don’t have to comply with ADS-B.

ADS-B not required in all airspace.
 
flyingcheesehead said:
I believe in your scenario everyone would see everyone. The GTX 345 is a dual-band unit, so it is speaking 1090 ES just like the airliners are.

Now, if you had a GDL 88 hooked up to a GTX 327, for example, instead of the 345s, then the GA planes and the airliners wouldn't see each other. Different frequencies, which normally require ADS-R (rebroadcast, ground-based) to get the data to the other guys.
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Thanks, getting more clear!!!

But to ask my follow up again...if no ATC radars were working...no transponders being swept by radars...would all the commercial guys and all the 345 guys in my example still see each other? Do they squit out a position periodically even without being swept by radar...or does this entire thing depend on ATC radars being active and hitting the planes?
 
TCABM said:
No. 978 vs 1090 - not every platform translates.

National Security waivers - some agencies don’t have to comply with ADS-B.

ADS-B not required in all airspace.
Click to expand...
In my example all the GA planes have 345s so they would see each other. Unless someone is up above 18000 with an exemption I thought they all need mode s as well so I still think everyone would see everyone....except if there was no ATC radars...then it's unclear if mode s transponders squit in absence of a radar sweep????
 
Sinistar, this is I envision ADS-B will be like when implemented in Canada. Satellite based 1090ES ADS-B. The province of Quebec where I live is five times larger than France. Large portions of the territory have zero radar coverage.

Covering such a large, mostly inhabited wilderness would make no economic sense. So I believe we'll be eventually mandated to equip with 1090 ES based ADS-B out. I'll be able to pick up other 1090 ADS-B out equipped airplanes, but I won't see nordo airplanes, gliders, balloons, etc.

I am planning to install a Garmin GTX 335 in my airplane during winter 2019-2020. This will enable me to continue flying into my favorite spots in the U.S., plus I'll have the peace of mind that Aeron will provide my last known gps coordinates to the search party should my plane ever go down in the wilderness, something that's a lot more effective in helping find me than the old 121.5 ELT that's in my plane.
 
Pascal Forget said:
Sinistar, this is I envision ADS-B will be like when implemented in Canada. Satellite based 1090ES ADS-B. The province of Quebec where I live is five times larger than France. Large portions of the territory have zero radar coverage.

Covering such a large, mostly inhabited wilderness would make no economic sense. So I believe we'll be eventually mandated to equip with 1090 ES based ADS-B out. I'll be able to pick up other 1090 ADS-B out equipped airplanes, but I won't see nordo airplanes, gliders, balloons, etc.

I am planning to install a Garmin GTX 335 in my airplane during winter 2019-2020. This will enable me to continue flying into my favorite spots in the U.S., plus I'll have the peace of mind that Aeron will provide my last known gps coordinates to the search party should my plane ever go down in the wilderness, something that's a lot more effective in helping find me than the old 121.5 ELT that's in my plane.
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Thanks for your feedback...yeah Canada has huge areas of zero population.

So you bring up Satellite, I take it that means the signal sent of the transponder would need to reach the satellite? But just about everyone else needs the transponder antennae on the bottom of the plane to reach the ground receivers. That will be interesting.

And no one has yet answered my question (Sorry @Pascal Forget, just using your response for my other evil purpose)

Can ADS-B as it is designed today even work if a ATC radar does not first sweep the plane and initiate the transponder response?

Can ADS-B out devices send position data in the absences of ATC radar sweeping the plane?

I think I will start another thread for this specific question.
 
The A in ADS-B means automatic. You don't need ATC to make your transponder broadcast.

Antennae on the bottom are not a problem. Even though you think of satellites being overhead, in reality many are just above the horizon and most people with a bottom antenna have reported no problem using them to broadcast ADS-B signals to satellites.

So yes ADS-B out devices do send position data in the absences of ATC radar sweeping the plane.
 
Thanks! I started another thread which has a bit more specifics. Its all starting to make sense, especially ATC's role (if any).
 
When Skynet evolves it's going to use ADS-B to kill all the pilots and air travelers, first thing.
Then the self driving cars.
Then the rail systems.
Just you wait and see.
 
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