Another ADS-B Question

[John Collins]

I thought the whole idea of NextGen was to move away from radar surveillance all to together.

Anyone know what the expected accuracy is of the required TSO'd WAAS GPS source for the average GA aircraft?

John, thanks for the email to check Out performance.

It does not look like there is enough interest in doing ADSB in a sensible way. It's a good idea but poor execution can kill even the best ideas. I think I will just go any GPS source into a Mode S-ES for now to get the ground to send traffic (ala Dynon's current solution) and do like everyone else and wait till just before 2020 to use a proper GPS source. If the FAA is going to make this hard, I'll just pass on playing.

Radar is still an integral portion of the system and is not going away. The radar is the backup when the GPS system is OOS or an aircraft has an equipment failure. It also provides protection against spoofing a position.

When the system is working, which should be a very high percentage of the time and the norm, aircraft will be able to be kept closer to each other with greater flow. When it fails, the reversion back to radar spacing will occur with the lower positional accuracy. The system will also provide coverage in some areas that now do not have radar coverage, for example over the Gulf of Mexico and in mountainous areas. It will also enable some applications such as enhanced self separation and spacing in route, IOW you can be given a clearance to follow a target that you can't see visually but know their position and your aircraft is equipped with the tools to alert on a closure rate with the traffic.

The accuracy requirements are based on the basic surveillance needs. Originally, they were going to require a higher accuracy and integrity because they would eventually be needed in certain applications. The FAA was talked out of these stringent requirements in the final rule, although if an aircraft is to participate in some of the applications, it will need to meet the accuracy requirements to play in that ballgame. The basic requirements are in the rule 91.227 and specify:

(c) ADS-B Out Performance Requirements for NACP, NACV, NIC, SDA, and SIL--

(1) For aircraft broadcasting ADS-B Out as required under Sec. 91.225 (a) and (b)--

(i) The aircraft's NACP must be less than 0.05 nautical miles;
(ii) The aircraft's NACV must be less than 10 meters per second;
(iii) The aircraft's NIC must be less than 0.2 nautical miles;
(iv) The aircraft's SDA must be 2; and
(v) The aircraft's SIL must be 3.

(2) Changes in NACP, NACV, SDA, and SIL must be broadcast within 10 seconds.

(3) Changes in NIC must be broadcast within 12 seconds.

NACp is position accuracy, NACv is velocity accuracy, NIC is navigational integrity limits. All these are dynamic parameters and continually broadcast by the aircraft.

SIL describes the Position Source and a value of 3 means that the position source is certified to have a probability of exceeding the NIC containment radius by no more than 1 in 10,000,000 on a flight hour or per sample basis. Normally this is a static value. A portable ADS-B Out system is not certified and is supposed to be 0 and ignored by a certified receiver.

The SDA describes the ADS-B Out unit and must not have an undetected fault causing false or misleading information at a rate any greater than 1 x 10^-7 per flight hour. Only certified equipment may satisfy this criteria. It is a characteristic of the equipment and is static.

If the ADS-B Out system is compliant with either RTCA DO260B (1090ES) or DO282B (UAT) but one of the parameters above specified above are not within tolerances allowed, ATC will not use the position for any surveillance.

 

[Jay Honeck]

The roll-out date is 5 years away. Just because it doesn't work perfectly today in your airplane in a wee little corner of Texas does not make it a big issue.

Of course it's not a big issue -- it's just a minor annoyance in an otherwise awesome new glass panel. But my daily experience illustrates what to expect, for those who are being fed the company line from the manufacturers.

Bottom line: Wait. There's no need to spend the money now, for traffic, because it is unreliable, as yet.

That said, having "free" on board weather is great. I sure don't miss the monthly XM bill!

 

[Jay Honeck]

BTW: Mac has a good article in EAA Sport Aviation this month about "What happens if you don't add ADS-B by 2020?".

The bottom line answer, for many of us, is "nothing". Basically, you won't be able to fly anywhere that you can't fly today if you don't have a Mode C transponder.

Thus, for many pilots, the ADS-B mandate is no big deal, and doing nothing is a good option.

 

[rvator51]

Today was another perfect example of how un-ready (and unreliable) ADS-B is..

Jay, is there a possibility that your ADS-B transmitter is putting out a weak signal? (Transmitter, cable or antenna) If you get too far away from an ADS-B tower, it loses your signal and stops transmitting traffic to you? That might explain what is going on.

Regards,
Tom

 

[Jay Honeck]

Jay, is there a possibility that your ADS-B transmitter is putting out a weak signal? (Transmitter, cable or antenna) If you get too far away from an ADS-B tower, it loses your signal and stops transmitting traffic to you? That might explain what is going on.

Regards,
Tom

Ultimately, when ATC or FSS has the ability to answer this query: "Are the ground stations in this sector receiving me?", we will know. Until then, we are left in the dark.

Unless someone has ADS-B testing equipment -- a rarity. I only know one shop with that box. I think they paid $6000 for it.

 

[John Collins]

Ultimately, when ATC or FSS has the ability to answer this query: "Are the ground stations in this sector receiving me?", we will know. Until then, we are left in the dark.

Unless someone has ADS-B testing equipment -- a rarity. I only know one shop with that box. I think they paid $6000 for it.

They should buy a Stratus. With ForeFlight it will tell them if their system is configured correctly and working.

 

[murphey]

Instead of spending a lot to replace a nav com with a WAAS Navigator, one can just buy a UAT transmitter with its own WAAS antenna. That way you keep everything you've got in your stack, and just add one thing behind the panel, plus antenna. The WAAS GPS antenna in this case is the source and it is in this case dedicated to the UAT transmitter.

One such offering is the Garmin GDL 88. Buy it with the WAAS option and add it behind the panel to your old Mode C transponder and you will have ADS-B out with everything that will be required in 2020.

Probably there will be other similar offerings from other manufacturers, but that is the one I know of.

Isn't this the same idea as the NavWorx w/WAAS? 4480 for Garmin, 3500 for NavWorx.

 

[Jay Honeck]

Just a data point: We picked up FOUR ADS-B transmitters on our local flight today.

That's one more than ever before down here. We had traffic displayed on our EFIS and on our Nexus 7 from the ramp throughout the flight. The ADS-B system is firming up, along the Texas coast.

 

[CTLSi]

The roll-out date is 5 years away. Just because it doesn't work perfectly today in your airplane in a wee little corner of Texas does not make it a big issue.

Five years and 200,000 aircraft needing it. Even if all the avionics shops in existence worked day and night for the next five years, they can't get them all installed.

There will be 100,000 in non compliance by then.

 

[John Collins]

Five years and 200,000 aircraft needing it. Even if all the avionics shops in existence worked day and night for the next five years, they can't get them all installed.

There will be 100,000 in non compliance by then.

I hear this type of alarm quoted all the time now a days. First, in the 2012 FAA data there were estimated to be 188,000 aircraft in the GA fleet that had an electrical system. This is before the recent re-registration effort which will result in substantially reducing these numbers. Of these 154,000 had mode C capability. There are tens of thousands of aircraft that currently have mode C capability that never venture into a towered airport, much less into one of the dreaded areas near a class C or B airport and don't climb to 10,000 MSL except on a dare to prove they can do it. There are many more that rarely need to fly into or near a class B or C area and will forgo the expense. Remember, one can still fly into the airspace mandated by the rule as long as one obtains ATC approval, just like you can today if you don't have a mode C capability or your transponder is on the fritz.

 

[murphey]

I hear this type of alarm quoted all the time now a days. First, in the 2012 FAA data there were estimated to be 188,000 aircraft in the GA fleet that had an electrical system. This is before the recent re-registration effort which will result in substantially reducing these numbers. Of these 154,000 had mode C capability. There are tens of thousands of aircraft that currently have mode C capability that never venture into a towered airport, much less into one of the dreaded areas near a class C or B airport and don't climb to 10,000 MSL except on a dare to prove they can do it. There are many more that rarely need to fly into or near a class B or C area and will forgo the expense. Remember, one can still fly into the airspace mandated by the rule as long as one obtains ATC approval, just like you can today if you don't have a mode C capability or your transponder is on the fritz.

Nevada, California, Utah, Colorado, New Mexico, Wyoming, South Dakota...pretty much anyone who lives/flys in these states will need ADS-B.

Climb on a dare to 10K MSL? Pretty much everyone who lives in these states cruise at 10K and higher as a rule.

Flatlander. The new pejorative.

 

[lolachampcar]

Mr. Cantwell of the FAA recently testified in front of a Senate committee that (1) the mandate will not slip, (2) there are 140K aircraft that need ADSB-Out, (3) 100 per day need to be done to make the deadline and only 100 per month are being done. He went on to say the FAA is doing its part and that industry needs to step up.

This tells me that either the FAA is going to ground a lot of planes come 2020 or they are stoned and incapable of adding two plus two. They obviously know there is zero chance of aircraft being updated in time.

 

[MooneyDriver78]

This tells me that either the FAA is going to ground a lot of planes come 2020 or they are stoned and incapable of adding two plus two. They obviously know there is zero chance of aircraft being updated in time.

The only planes that will be grounded will be older GA planes, FAA doesn't care about them, heck if they can ground jets in 2015 for not meeting noise standards, they can ground anybody. Those jets will have to install hushkits, costing hundreds of thousands. If you think they will care that ADS-B compliance is going to cost you several thousand, you're crazy.
For those of you not familiar with noise issue:
http://www.ainonline.com/aviation-n...faa-stage-2-noise-ban-rule-bars-older-jets-us

 

[timrb]

Nevada, California, Utah, Colorado, New Mexico, Wyoming, South Dakota...pretty much anyone who lives/flys in these states will need ADS-B.

Climb on a dare to 10K MSL? Pretty much everyone who lives in these states cruise at 10K and higher as a rule.

I don't know about the other states, but you can take California off your list. It's very easy to fly here without going over 10k feet. In fact, in 16 years of flying I have only done it once, and that was just to see how high I could go.

Tim

 

[dans2992]

Nevada, California, Utah, Colorado, New Mexico, Wyoming, South Dakota...pretty much anyone who lives/flys in these states will need ADS-B.

Climb on a dare to 10K MSL? Pretty much everyone who lives in these states cruise at 10K and higher as a rule.

Flatlander. The new pejorative.

You can add AZ to that list - especially if you fly IFR.

 

[CTLSi]

I don't know about the other states, but you can take California off your list. It's very easy to fly here without going over 10k feet. In fact, in 16 years of flying I have only done it once, and that was just to see how high I could go.

Tim

You can take CA off lots of lists for lots of reasons. But a third of the state is mountains. I know guys that live in Mammoth and they have never see sea level. I know guys that live in Truckee, likewise. Or around Lake Almanor. The coastal guys apparently think they are the only flyers that live in the state, sorta classic CA arrogance huh?

 

[Indiana_Pilot]

What kind of reception are you guys seeing in Indiana ? I have flown around 7,500' with the GDL39 on the dash and I receive no ground stations at all..This is South Eastern Indiana between KIND and KCVG.. I always see "degraded TIS-B" The only time I did see it work well was when I flew close to Indianapolis International AirSpace.. I do however see ads-b targets directly from other aircraft 50-100 NM miles away..

I am guessing it's because I don't have ads-b out and it's not activating the ground stations? I don't get why they don't just turn on transmissions all the time. (unless they are trying to give people a reason to equip their aircraft?)

 

[timrb]

You can take CA off lots of lists for lots of reasons. But a third of the state is mountains. I know guys that live in Mammoth and they have never see sea level. I know guys that live in Truckee, likewise. Or around Lake Almanor. The coastal guys apparently think they are the only flyers that live in the state, sorta classic CA arrogance huh?

Mammoth elevation: 7800 ft
Truckee elevation: 5817 ft
Lake Almanor elevation: 4505 ft

I have flown to mountain destinations and not had to go anywhere near 10k feet, but then I AM quite arrogant.

Tim

 

[bnt83]

Nevada, California, Utah, Colorado, New Mexico, Wyoming, South Dakota...pretty much anyone who lives/flys in these states will need ADS-B.

Climb on a dare to 10K MSL? Pretty much everyone who lives in these states cruise at 10K and higher as a rule.

Flatlander. The new pejorative.

I rarely get over 7500, no point to it.

Our rotary winged air ambulance drivers say they rarely cruise above 3k

 

[weirdjim]

I rarely get over 7500, no point to it.

Our rotary winged air ambulance drivers say they rarely cruise above 3k

In Nebraska you can roll a bowling ball from Lincoln to Scottsbluff without hitting much.



Jim

 

[bnt83]

In Nebraska you can roll a bowling ball from Lincoln to Scottsbluff without hitting much.



Jim

There are a couple reaaaaalllyy tall towers by Omaha with VERY bright lights. See and avoid

 

[dans2992]

What kind of reception are you guys seeing in Indiana ? I have flown around 7,500' with the GDL39 on the dash and I receive no ground stations at all..This is South Eastern Indiana between KIND and KCVG.. I always see "degraded TIS-B" The only time I did see it work well was when I flew close to Indianapolis International AirSpace.. I do however see ads-b targets directly from other aircraft 50-100 NM miles away..



I am guessing it's because I don't have ads-b out and it's not activating the ground stations? I don't get why they don't just turn on transmissions all the time. (unless they are trying to give people a reason to equip their aircraft?)

Yes, it's because you don't have ADSB out and yes, that is unfortunately the reason it's not broadcast all the time.

 

[gismo]

What kind of reception are you guys seeing in Indiana ? I have flown around 7,500' with the GDL39 on the dash and I receive no ground stations at all..This is South Eastern Indiana between KIND and KCVG.. I always see "degraded TIS-B" The only time I did see it work well was when I flew close to Indianapolis International AirSpace.. I do however see ads-b targets directly from other aircraft 50-100 NM miles away..

I am guessing it's because I don't have ads-b out and it's not activating the ground stations? I don't get why they don't just turn on transmissions all the time. (unless they are trying to give people a reason to equip their aircraft?)

You should be able to receive FIS-B (weather) but you'll only get traffic when you are inside the 22 nm "puck" surrounding another aircraft which is ADS-B out equipped and it's configured to receive traffic on 978MHz.

 

[MooneyDriver78]

Yes, it's because you don't have ADSB out and yes, that is unfortunately the reason it's not broadcast all the time.

I thought they did that to save bandwidth, also the reason why the have 978 with weather, with all the info they are transmitting, the 1090 band is going to be crowded, they wanted to save that for high flyers

 

[John Collins]

You should be able to receive FIS-B (weather) but you'll only get traffic when you are inside the 22 nm "puck" surrounding another aircraft which is ADS-B out equipped and it's configured to receive traffic on 978MHz.

15 NM radius. The GDL39 receives on both frequencies, so a TISB report on either frequency can be generated by the GBT, depending on what the client aircraft indicates it is capable of receiving. Except in a few areas around a major airport, I don't see much of this.

 

[Palmpilot]

...sorta classic CA arrogance huh?

Classic anti-California prejudice.