brien23
Pattern Altitude
After 2020 why do I need a transponder. Since ADS-B is a stand alone system and radar will no longer be used in the ATC system why would you need a transponder.
ADS-B out
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Capt. Geoffrey Thorpe
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Light and Sporty Guy
If ATC were to quit using radar, turning off your ADS-B (or if it malfunctions) would make you totally invisible to the system. Radar is not going away, transponders are not going away.
brien23
Pattern Altitude
The whole idea of ADS-B is that it does not use radar. So why do I need to upgrade my transponder to ES.
brien23
Pattern Altitude
brien23
Pattern Altitude
The whole idea is to get rid of Radar and the cost of upkeep, after 2020 a lot of Radar will just go away. And why would you want to backup a system that is so perfect as the new ADS-B system. Don't you have complete faith in the FAA and ATC to provide us with a perfect system.
Because the second sentence is incorrect. Where did you read that?
Go read 14 CFR 91.251, 91.227 (d)(7) and 91.411(a)(3)
No where does 14 CFR 91.xxx eliminate the requirement for a transponder.
I repeat - provide your source, and it really needs to be a credible, irrefutable source. Every ADS-B unit I've seen either replaces the existing transponder with an integrated ADS-B and transponder, or has a sync capability to the existing transponder.
Quoting from the FAA's FAQ:
"For the most part, ADS-B Out will be required in the same airspace where transponders are required."
So, if you never fly anywhere that requires a transponder, you won't be required to have ADS-B.
brien23
Pattern Altitude
The question is not that it will still be required, the question is why?
brien23
Pattern Altitude
The key difference between the two solutions is that UAT has spare uplink bandwidth, whereas Mode S Extended Squitter only has the capacity for ADS-B position reporting. That means that a UAT radio can receive additional data streams, in addition to the traffic information. The FAA is providing a weather reporting function using the spare datalink bandwidth of the UAT radio, and the FAA is hoping that this “added value” feature will encourage GA operators to install ADS-B equipment sooner than they otherwise might.
Clark1961
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Already answered.
We could discuss further the potential benefit of having some redundancy in the systems, both in terms of position and separation. For those of us who have dealt with fairly frequent radar service outages the redundancy may be helpful. I'm sure the ADS-B system will have its share of glitches. Probably fewer on the mechanical side but more on the software side at least early on.
And then there is that whole thing about airspace surveillance...
brien23
Pattern Altitude
Do you understand the ADS-B system. If you have a transponder mode S with ES and input a GPS to it with frequent radar service outages where is the redundancy. UAT radio can receive additional data streams, in addition to the traffic information. As for 14 CFR 91.251, 91.227 (d)(7) and 91.411(a)(3) after 2020 look for one or the other not two, make your choice now their are pro and con for each.
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As already said, ADS-B out isn't required everywhere. So theoretically, I could fly IFR / VFR FF from a class D to another class D airport below 10K with my mode3 A/C transponder. In order to provide ATC service for that operation, the FAA will still have to keep our primary and SSR systems operational.
Clark1961
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Where is the redundancy? I think you don't understand that radar and ADS-B are two separate systems. Yes, after 2020 there will still be two systems. Try to calm down a bit and understand that radar is not going away.
brien23
Pattern Altitude
After 2020 you will only need one of the two systems one or the other. A lot of the old radar in the system will go away and not be replaced along with some VOR'S My point is if you want ADS-B in UAT and all the goodies with it why would you need a transponder based system mode S ES. If you go with the transponder system you can't get all the goodies that ADS-B in have. Most of the radar systems around are old and prone to fail do you think they are going to spend the money to replace them.The new updated system of ADS-B is what the FAA has bet everything on and their not going backward to Radar. Does anyone know if their is a overlay of Radar on the new ATC displays for ADS-B.
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brien23 said:
I'm not following. With whichever ADS-B out solution you have, you won't have full ADS-B In (traffic) data unless 1) you have the ADS-B Receiver Installed bits set on your out transmission telling the ground station you have a receiver onboard, and 2) you have an ADS-B In receiver, be it a portable or installed receiver. Also, if you have a UAT system installed, you will need a Mode A/C transponder to fly in transponder required airspace and to be seen by TCAS / TAS traffic systems.
Clark1961
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The radar systems aren't going away.
brien23
Pattern Altitude
Does anyone know if the new NextGen ATC displays have a Radar overlay on them.
brien23
Pattern Altitude
Mode S ES is on 1090mhz UAT ADS-B is on 978mhz not the same.
dans2992
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I realize that, but you can comply with the ADS-B mandate with either (below FL180).
The 1090 solution just requires a transponder upgrade. The UAT solution means you have to add additional equipment for UAT, _plus_ continue to maintain your Mode C/S transponder.
brien23
Pattern Altitude
After 2020 mode S ES you still have to certification every 2 years 14 CFR 91.413, and that is one solution. The other is UAT no transponder no 2 year cert. each is a separate solution after 2020 you only need one.
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brien23
Pattern Altitude
After 2020 all class A,B,C will be ADS-B out required Class D will have it but not required, and may have radar or may not.
BillTIZ
Final Approach
UAT does not negate the requirement for a transponder.
ADSB out does not negate the requirement for a transponder.
The requirements of 91.215 are not rescinded. If you fly in airspace requiring a transponder now, that does not change after 2020.
denverpilot
Tied Down
Incorrect. Where are you getting this stuff?
FAA has stated, in public, in writing, that radar systems are still required after 2020.
They have not "bet everything on ADS-B". They do market it HEAVILY under the brand name "NexGen" which really has no written definition and has changed numerous times since we first heard it as a marketing term not long after "Free Flight" which fell out of favor in the early 1990s for the much vaguer and less defined "NexGen".
Which specific new "ADS-B displays" are you referring to? Model number please. And contractor installing them. I suspect you'll find that display technology is being de-linked in general from any particular system and is being fed upstream by various systems.
One active system I am aware of that feeds into Denver Center's displays, as an example of de-coupling from Radar is the Wide Area Multilaterization system consisting of multiple tower sites in the Aspen valley which use a single central transmitter to broadcast a transponder interrogation and multiple receivers at different sites to triangulate where the aircraft responding are located by time-delays measured between the sites. That data is aggregated into "radar" data and fed to the ZDV controllers for that area, which otherwise is difficult to cover with primary radar and never had coverage until the WAM system was deployed.
It requires nothing but an on board transponder for aircraft location and identification via the standard transponder codes issued by ATC.
You've somewhere along the line picked up the idea that ADS-B replaces Radar. It does not.
Think airspace defense. Many of the FAA long range primary radar systems are jointly used by FAA and DoD. Bad airspace players aren't going to show up happily pinging away on ADS-B. And both organizations don't need to run separate systems, always. (They do run some separate systems but that's because for other types of radar they need more speed or different frequencies for various reasons. But they do share many common systems as well.)
And then there's the failure modes in aircraft of both transponders and ADS-B systems. Namely, electrical system failures for just a start. Knocking the dang antenna off the belly for another. Primary radar is still needed in certain locations and places and always will be.
Yes, the vast majority of the time FAA declutters the screen and operates off of secondary radar, transponders, and those aren't going away any time soon.
This.
ADS-B is NOT a replacement system.
It is an ADD-ON system.
It's also really TWO systems, each with individual failure modes and issues. The most basic of which are coverage and antenna blocking. Your antenna on your airplane may or may not hear a Mode-S aircraft even if you're equipped with both bands. And it may or may not be line of sight to a 978 MHz tower at any one particular time. Just like you may or may not today be in radar coverage.
All it takes is missing the one traffic announcement you needed to receive and you're going to have only one way to miss that aircraft -- see and avoid, or a controller separating you from the other aircraft.
Will it work some very high percentage of the time aloft? Yes. Does it have flaws that can make it not work even when everything in the system is operating at best possible behavior? Yes. It is NOT a panacea. It's tech. It has flaws.
It took YEARS for the general pilot community to understand the silly "hockey puck" problem -- and that behavior was fairly well documented. You must be a radar or ADS-B participating aircraft for the system to even send up traffic relative to your position. You can google search "ADS-B hockey puck" for more information.
Similar failures of other scenarios will take FOREVER to find and document. People who ARE participating aircraft HAVE documented occurrences where traffic was not displayed. To troubleshoot that, you need detailed logs from both ADS-B receivers on board and a confirmation that the local tower actually transmitted the data up.
And nobody owns all three pieces in one place, so until FAA publishes what was transmitted in a timestamped format, you can't tell if the failure was badly formatted data, an antenna blocked, a faulty receiver that isn't as sensitive as it should be, local RF interference at a particular location, group delay/phase/reflection problems caused by local terrain or other large features, etc etc etc.
Let alone the fact that the transmissions CAN be spoofed, because there isn't even a tiny bit of standard RF data network security built into the current spec... but as far as anyone knows, that hasn't become a widespread problem... yet.
There. You didn't use the search box and didn't research. So there's just a small summary of problems with ADS-B. The obvious ones. There's going to be real subtle ones that nobody thought of like any massive distributed RF data system has, that'll take a long time to figure out.
brien23
Pattern Altitude
I will ask again do the ATC center new displays for ADS-B have a Radar overlay on their screens. If they do not what good is the radar if they can't see it.
Checkout_my_Six
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our tower has no radar....just an ADS-B feed.
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Velocity173
What new displays have they gotten? The current system already has a mix of ADS-B and traditional primary and ATCRBS in them. Some have the ADS-B portion disabled but they won't need different displays in the future to see both.
brien23
Pattern Altitude
Do you have a link to show what ATC will be using in 2020 for displays. I do not assume they will still be using the same old displays they have now, or do you know something no one else knows.
brien23
Pattern Altitude
ATC display that is showing ADS-B real time and your going to overlay radar old information last sweep over it would be a unreadable mess just what good would radar overlay of ADS-B do, I guess common sense does not count for much.
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The system already supports ADS-B with traditional radar / ATCRBS. There would be no need to replace any scopes to support the 2020 mandate. I took a tour in Altanta approach and theirs is up. The ADS-B target just has a different icon than a Mode 3 A/C or S icon.
Some have disabled theirs due to reliability errors. It was also disabled for a period of time because controllers were using wrong separation standards for ADS-B vs non ADS-B targets. That has since been clarified by the FAA and they're back in business.
brien23
Pattern Altitude
I repeat - provide your source, and it really needs to be a credible, irrefutable source.
denverpilot
Tied Down
No, you're the one saying they're getting "new displays" -- you'd have to show the contract that's installing those.
Oh, you're asking how they'll tag targets seen by more than one system? That's been going on for decades. The ADS-B data includes an identifier and the radar data includes the transponder code.
Most "radar" data today is already interpolated into expected movement from one "sweep" to another on the long range slow radars, they're not usually looking at the raw data. Look for "coast" mode information when radar data is missing/lost.
Combining the new data with the old is no big deal. On faster approach control radars, its even easier. The displays are already a composite of various information, "smoothed" by computer.
All I need to know is how to do the ADS-B out only. I just want to be legal to the new reg, least expensive way. I have a King KT76 and a non-WAAS GPS. I would prefer UAT solution due to info concerns. And the name of an avionics place that can actually do it. No more than necessary for minimal compliance thank you.
denverpilot
Tied Down
Some guy made an excel spreadsheet of the options over on Reddit. It's already outdated.
Prices changed, NavWorx happened, etc. But it only has about what, six to eight vendors?
He also had to make it more complex because he wanted to meet the goal of "Wifi to an iPad" from his system, so he showed which combinations of gear would do that.
I haven't seen anything done better than that.
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Velocity173
Lol! Coming from the guy who has no source. Just a hunch that they're getting new displays to replace their old ones. It's not like many facilities are using the 1950s displays like I used anyway. FAA started phasing those out years ago. The problem you talk of with a sweep display (single sensor radar), is quickly becoming a thing of the past as well. Like Nate brought up, fusion and mosaic radar is taking over. You have like a one second refresh radar from multiple antennas. Yes, you CAN display ADS-B with traditional ATCRBS. From the .65:
4. ADS-B may be integrated as an additional surveillance source when operating in FUSION mode. The display of ADS-B targets is permitted and does not require radar reinforcement.
NOTE−
ADS-B surveillance must only be used when operating in FUSION.
Alaska has been using both for a long time:
http://www.ainonline.com/aviation-n...11-17/alaska-ads-b-returning-atc-radar-scopes
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BillTIZ
Final Approach
You will need a system with a WAAS GPS receiver.
If you go UAT for ADSB out, you still need to keep the KT76 and altitude encoder.
It looks like we will go with the Aperro unit. It replaces our KT, has a built in WAAS receiver and works with our encoder. Serves both transponder and ADSB out requirement in box. It is on 1090ES and not UAT. Saves panel space.
Your UAT out system will need to be able to read and replicate your transponder code for the UAT broadcast.
FAA has stated that pilots should only need to interact with one box for xpndr codes.