ADSB?

[Mike M]

OK, I'm confused again. I thought every aircraft in Alaska was outfitted with ADSB to prevent midair collisions?

http://www.foxnews.com/us/2015/02/01/small-plane-collides-with-aircraft-in-alaska/?intcmp=latestnews

[FlyingRon]

It's only good if it's turned on and people are paying attention to it. The CAPSTONE units don't have the assertiveness of TCAS in screaming at the pilots.

[Frank Giger]

I've always thought of ADSB as a precautionary tool in that it advises a pilot of aircraft that are in proximity of one's own - but only that. "Hey, there's an aircraft within three miles...two miles...one miles from you," letting one know to (and where to) look for it, much in the same way that a radio traffic call out at an uncontrolled airfield does.

ADSB will tell one where an aircraft is, but not where it's going. Even a track is historical and a predictive one would only be predictive.

Data and information are two different things, and as pilots we have to remind ourselves of it as we get more whiz-bangs.

A tachometer can tell us RPM's are dropping. The altimeter can tell us we're losing altitude. The throttle can tell us we haven't changed the setting. It's only by turning all of that data into information that gets us to pull the carb heat handle, as an example.

[Gunslinger37]

On Monday the FAA made a correction to the ADS-B rule that opens the door to non-TSO products that meet the requirements but have not been through the expensive TSO testing. This wording change is substantial. This might allow the manufacturers to make lower cost units, perhaps even hand-held ADS-B products, for the Experimental, LSA, even VFR GA low end aircraft. See more in the EAA News section.

[TedK]

On Monday the FAA made a correction to the ADS-B rule that opens the door to non-TSO products that meet the requirements but have not been through the expensive TSO testing. This wording change is substantial. This might allow the manufacturers to make lower cost units, perhaps even hand-held ADS-B products, for the Experimental, LSA, even VFR GA low end aircraft. See more in the EAA News section.


EAA News article:

https://www.eaa.org/en/eaa/eaa-news-and-aviation-news/2015-news/02-09-2015-faa-rule-correction-opens-door-for-lower-cost-ads-b

[steve]

The non-TSO'd equipment must still perform like TSO gear. Therefore it must be tested. Therefore the manufacturer might as well apply for the TSO. What lower cost units?
Until the FAA changes the rule to allow non-ADS-B Out equipped airplanes to fly under the Class B layers inside the 30 nm veil, it's game over for many pilots and airplane owners.

[Marc Zeitlin]

The non-TSO'd equipment must still perform like TSO gear. Therefore it must be tested. Therefore the manufacturer might as well apply for the TSO. What lower cost units?
Until the FAA changes the rule to allow non-ADS-B Out equipped airplanes to fly under the Class B layers inside the 30 nm veil, it's game over for many pilots and airplane owners.Disagree. There are already units that are low cost that do ADS-B out. Skyguard TWX sells a transceiver for $1500:

http://adsb.skyguardtwx.com

While they are in the process of applying for a TSO (so therefore believe that they've met the technical requirements), this unit works (I know folks that have them), puts you into the system in what would be a legal manner and while not exceedingly cheap, is not out of line for avionics. It's MUCH cheaper than the current batch of TSO's units, which start around $3K - $4K, and the sky's the limit.

I imagine that many of the other ADS-B IN unit MFG's will add ADS-B OUT to their systems, especially if they know that the Exp. market is looking for this and the FAA explicitly allows it.

I don't think the FAA needs to do anything more than they've just done (and it's not even obvious they needed to do that, since, assuming the TWX system gets its TSO approval, there'd be a TSO'd unit on the market for $1500) to ensure that the game is not over for many pilots and owners.

[cub builder]

Skyguard's web site says they will come out with a TSO kit once the TSO rules are complete. They don't claim to meet the TSO performance standard. However, I believe their equipment does meet the performance standard. Their TSO kit was to contain 1) an external mount antenna to replace the suction cup mounted ADS-B Out antenna, 2) the FAA TSO approved GPS puck (read high $$), and 3) a software patch that effectively sets a bit in the transmission stream to say it is a TSO approved unit. I'll bet their web site gets updated soon to reflect meeting the TSO standard.

With the FAA's correction to the rulemaking, if the unit itself meets the performance standard, it should be good to go for under $1000 for their ADS-B out only unit or <$1500 for an all in one unit.

Many manufacturers produce avionics for the E-AB and LSA markets and never bother to get a TSO. MicroAir, X-com, and Dynon are the first to come to mind.

Cub Builder

[Marc Zeitlin]

Skyguard's web site says they will come out with a TSO kit once the TSO rules are complete. They don't claim to meet the TSO performance standard.Yeah, they do. If you read their blog, they've submitted to the FAA twice now - the 2nd time in January. If they didn't believe that they met the standard, they wouldn't have submitted, because the paperwork is a PITA.


However, I believe their equipment does meet the performance standard. Their TSO kit was to contain 1) an external mount antenna to replace the suction cup mounted ADS-B Out antenna, 2) the FAA TSO approved GPS puck (read high $$), and 3) a software patch that effectively sets a bit in the transmission stream to say it is a TSO approved unit. I'll bet their web site gets updated soon to reflect meeting the TSO standard.Soon is relative :-). They say that it's in the FAA's hands now, and they expect a 2nd round of request for more info, so I'd bet it's many months before approval.


With the FAA's correction to the rulemaking, if the unit itself meets the performance standard, it should be good to go for under $1000 for their ADS-B out only unit or <$1500 for an all in one unit.I certainly hope you're correct.

[Frank Giger]

With the FAA's correction to the rulemaking, if the unit itself meets the performance standard, it should be good to go for under $1000 for their ADS-B out only unit or <$1500 for an all in one unit.

And this is the key to all TSO/non-TSO'd equipment.

What's the difference between a TSO and a non-TSO'd vertical card compass? Two hundred dollars (or more). They both work the same, give the same results, and are both accurate in the exact same ways. But only one of them is legal to install into certified aircraft, which must have all certified parts in them in order to stay certified.

If there's a production line that produces the same product in the same way for the same company, why do those in the TSO bin at the end of it cost more? To cover the certification costs and in a little bit because they can. If one owns a C172 it doesn't matter if they're giving away non-TSO ADSB units with hats at AirVenture, he can't install it on his aircraft. He's going to have to pay whatever the market has agreed to price TSO'd ADSB units at.

Since us homebuilders are a largely optional market for stuff, they put a certain percentage of production at a reduced price out for us (and some companies forgo certification entirely in order to speed up production process times). Skyguard is doing this. They could hold up production and sales as they await certification or they can sell now as non-TSO while their sample products wind through the government process.

Either way the FAA doesn't care. If one has a functioning ADSB-out unit that's been properly installed and working they won't know it's not non-TSO'd and will be pleased that it's there.

[L16 Pilot]

Kind of like "aircraft radios". When I had my Cherokee I spent a pile of $$$ trying to keep the (TSO'd) radios working. Now I fly with a $250 handheld that actually keeps working and not TSO'd by the way.

[cub builder]

Yeah, they do. If you read their blog, they've submitted to the FAA twice now - the 2nd time in January. If they didn't believe that they met the standard, they wouldn't have submitted, because the paperwork is a PITA.

From their web site one could deduce that it likely meets performance standards since they submitted for TSO Authorization. However, the TSO testing is with a different GPS puck and different antenna from what is being sold as a "portable" unit. I haven't read their blog as it is closed to those not registered.


Soon is relative :-). They say that it's in the FAA's hands now, and they expect a 2nd round of request for more info, so I'd bet it's many months before approval.

Again, that is for the TSO certification. Their units likely currently meet the TSO performance standard with their current GPS puck and "portable" antenna mounted internally in my wood and glass plane.


I certainly hope you're correct.

I bet my money on it several months ago when I bought one of their units. Once I see a statement on their web site stating that they meet the performance standards, I'll buy a second unit for my Exp SuperCub. Since meeting the performance standard makes it 2020 legal for the E-AB and LSA Aircraft, they may not necessarily even want to get the TSO certification unless their projected sales warrant it. Wish I could say that I foresaw this change in the FAA's interpretation of their rule, but I didn't. I decided I would like to have the weather and traffic data in flight now and would worry about 2020 in 2020. It's been my plan all along to continue using this unit as I don't spend much time in Class B or C airspace anyway.

-Cub Builder

[MEdwards]

People here are assuming the Skyguard unit meets the required TSO performance specifications. There's an easy way to find out. The FAA offers to send users a report showing whether their ADS-B Out transmissions met the specs on a particular flight. All you have to do is send an email asking for one. The email address is:

9-AWA-AFS-300-ADSB-AvionicsCheck@faa.gov

Supposedly, you need to include the N number, date, time, type of installed equipment (navigator and ADS-B solution), as well as departure or nearby airports. I have also heard people say all they gave was their N-number and they got the report back within hours.

[Gunslinger37]

You have touched upon one of the problems with a "portable" ADS-B that could be moved from aircraft-to-aircraft. If someone like Garmin were to make a ADS-B OUT version of their GDL 39, they would need a way for the Broadcast Message Elements to be entered into the device, so that the aircraft N number and base 16 hex code could be transmitted.

BTW did you see that NavWorx just announced a "fully compliant" ADS-B In/Out for $699. The same unit with TSO sells for $2500.

[cub builder]

You have touched upon one of the problems with a "portable" ADS-B that could be moved from aircraft-to-aircraft. If someone like Garmin were to make a ADS-B OUT version of their GDL 39, they would need a way for the Broadcast Message Elements to be entered into the device, so that the aircraft N number and base 16 hex code could be transmitted.

BTW did you see that NavWorx just announced a "fully compliant" ADS-B In/Out for $699. The same unit with TSO sells for $2500.

Imagine that? Navworx reacted to the FAAs change to the market to take advantage.

The portable ADS-B Out units have an app already installed in your GPS software so you can change the Broadcast Message Elements. When my iFly (or iFly software on my Droid) sees one of the many ADS-B out devices it can work with, it enables an app on the GPS that I can select to configure the ADS-B unit. I would assume most of the other GPS softwqaare packages have preloaded ADS-B out control apps in them.

Question on the ADS-B units for someone that knows more about this than me. Flying with ADS-B traffic, I see altitudes reported all over the place and usually incorrectly. My SkyGuard unit is broadcasting WAAS GPS derived altitude. The Navworx unit ties into an altitude encoder so reports pressure altitude. Aircraft broadcasting Mode-C are reporting pressure altitude, but that is picked up by Center's radar and apparently has a Barometric Pressure Correction applied before broadcasting traffic information out via the ADS-B tower. Due to the variable terrain in my part of the country, the corrected Mode C altitudes for the traffic that is rebroadcast from the ADS-B towers is also usually off by 200 - 400'. My observation is that the altitude reporting for traffic seems to be all over the map, usually with errors of 200 - 400'. So how does the ADS-B performance spec say the altitude is to be derived? If it is to be pressure altitude, then the Skyguard unit can't comply. Or does the performance spec even say? We know Skyguard has submitted their equipment for evaluation, so they apparently think they comply. Or perhaps the FAA assumes GPS altitude, pressure altitude and corrected pressure altitude are close enough even though they want to require WAAS III for position??? I'll be curious to see what you guys that like to delve into the regs can derive.

-Cub Builder

[TedK]

Question on the ADS-B units for someone that knows more about this than me. Flying with ADS-B traffic, I see altitudes reported all over the place and usually incorrectly. My SkyGuard unit is broadcasting WAAS GPS derived altitude. The Navworx unit ties into an altitude encoder so reports pressure altitude. Aircraft broadcasting Mode-C are reporting pressure altitude, but that is picked up by Center's radar and apparently has a Barometric Pressure Correction applied before broadcasting traffic information out via the ADS-B tower. Due to the variable terrain in my part of the country, the corrected Mode C altitudes for the traffic that is rebroadcast from the ADS-B towers is also usually off by 200 - 400'. My observation is that the altitude reporting for traffic seems to be all over the map, usually with errors of 200 - 400'. So how does the ADS-B performance spec say the altitude is to be derived? If it is to be pressure altitude, then the Skyguard unit can't comply. Or does the performance spec even say? We know Skyguard has submitted their equipment for evaluation, so they apparently think they comply. Or perhaps the FAA assumes GPS altitude, pressure altitude and corrected pressure altitude are close enough even though they want to require WAAS III for position??? I'll be curious to see what you guys that like to delve into the regs can derive.

-Cub Builder

ADS-B Out is required to be integrated to a Pressure Encoder, and it has to be the same Encoder that is feeding the Mode C transponder.

This requirement will hamstring portable ADS-B Out.

[Marc Zeitlin]

So how does the ADS-B performance spec say the altitude is to be derived?According to AC20-165, it's Baro pressure, although there's some mention of GPS derived altitude as well. It does say this:

Installation Guidance.(1) The barometric altitude used for the ADS-B broadcast must be from the samesource as the barometric altitude used for the ATC transponder Mode C reply, if analtitude-encoding transponder is installed in the aircraft.

Not sure what Skyguard will do about that.

HOWEVER, the AC alludes to, and the RTCA DO-282B seems to indicate that either the Baro or GPS "Height above Ellipsoid" altitudes may be acceptable, so maybe that's all that Skyguard needs to supply. See:

http://adsb.tc.faa.gov/WG5_Meetings/Meeting27/UAT-DO-282B-FRAC.pdf

But Navworx has a full solution (and at 1/2 the price, apparently - wheee!).

Progress, and fast!

[Marc Zeitlin]

ADS-B Out is required to be integrated to a Pressure Encoder, and it has to be the same Encoder that is feeding the Mode C transponder.

This requirement will hamstring portable ADS-B Out.Maybe - it says that IF you use pressure altitude, it must be the same as from the Mode C. But as I indicated above, at least a cursory reading of the DO-282B document seems to indicate that maybe the HAE from GPS is also acceptable. Don't know...

[TedK]

I couldn't do a cursory read of the 670 or so pages of the MOPS without my eyes rolling back in my head, but the advisory circular seems pretty clear that Baro Alt is required and should be the same source as used for Mode C.

Why would anyone go thru the trouble of integrating the ADS-B to Baro Alt if they didn't have to?

[Kyle Boatright]

You have touched upon one of the problems with a "portable" ADS-B that could be moved from aircraft-to-aircraft. If someone like Garmin were to make a ADS-B OUT version of their GDL 39, they would need a way for the Broadcast Message Elements to be entered into the device, so that the aircraft N number and base 16 hex code could be transmitted.



I realize it is part of the regulation, but the question is "Why?". There is no legitimate reason VFR aircraft need to be identified by N-number on whatever system(s) the FAA is running.

[TedK]

I realize it is part of the regulation, but the question is "Why?". There is no legitimate reason VFR aircraft need to be identified by N-number on whatever system(s) the FAA is running.

The UAT units have an anonymous mode. No reason to have an N number entered. The only thing that really seems to hamstring a portable UAT is the requirement to be integrated to an installed encoder that has passed its checks. And installed GPS and ADS-B antennas to give acceptable performance (yeah, thats the new requirement, have to meet the performance requirements)

I suppose you might be able to modify your encoders harness with some sort of a pigtail that was ready to plug into a portable ADS-B. You could drag the box from airplane to airplane, but each would have to have an already installed and ready encoder pigtail, GPS antenna and ADS-B antenna.

[cub builder]

I suppose you might be able to modify your encoders harness with some sort of a pigtail that was ready to plug into a portable ADS-B. You could drag the box from airplane to airplane, but each would have to have an already installed and ready encoder pigtail, GPS antenna and ADS-B antenna.

It's not clear to me that pressure altitude is required.

From Minimum Operational Performance Standards for UATs:



3.5.3 Altitude
Two sources of Altitude Data are defined in the ADS-B System. Barometric Pressure Altitude relative to a standard pressure of 1013.25 millibars (29.92 in.Hg.) shall be supplied to the ADS-B system. Altitude data, which is corrected for local barometric pressure, shall not be supplied to the ADS-B system. The ADS-B system and the ATC transponder (if installed) shall derive Pressure Altitude from the same sensor (e.g., air data computer or encoding altimeter). If a pressure altitude source with 26-foot or better resolution is available on the aircraft, that source shall be connected to the ADS-B Transmitting Subsystem. Geometric Altitude is derived from the height above the WGS-84 ellipsoid by the GPS/GNSS navigation receiver.

3.5.3.1 Altitude Reporting Source
An interface shall be provided that allows the flight crew to disable the reporting of Barometric Pressure Altitude by the ADS-B equipment.
Note that it says two sources are defined, not required. There is a bit set in the UAT transmission that tags the altitude source as either Pressure Altitude or GPS Altitude. Additionally, the requirement to connect to a pressure altitude is for a 26 foot or better resolution in pressure altitude. Mode-C only has 100 foot resolution.

Tons or reading in this document, and more than I'm willing (or able) to digest. Depending on interpretation, it could be interpreted as self conflicting.

Cub Builder

[CharleyB]

NavWorx has recently come out with a non-TSO ADS-B-out device for Experimental Aircraft. It is offered at a limited time price of $600. It is a remotely mounted box that will use currently installed transponders, has its own WAAS GPS, and will provide ADS-B-In info vial WiFi or a RS-232 cable. Basically a plug and play box.

It is my understanding that it will require testing and certification similar to what is now required for ordinary transponders to legally fly IFR. I also understand that the testing equipment is very expensive and few avionics shops now have the equipment. It is safe to say certification will be expensive and probably have to be done every two years.

For more details, see the following:

http://www.navworx.com/navworx_store/Experimental_Aircraft_Transceivers/ADS600_EXP.html

[cub builder]

Re: SkyGuard, do they or don't they meet the performance specs?

-----
From Skyguard:
We have been talking with the FAA on exactly what this new rule update
for experimental aircrafts means. Even our local FAA (ACO) office does
not yet have the details. As we interpret the new wording, it seems to
state that you can put a non-TSO'd ADS-B Transmitter/Transceiver in
an "experimental class" aircraft and you would be meeting the 2020
mandate. But we don't yet have an official answer on that from the FAA.
The big question is will this non-certified unit be required to have a
certified GPS position source? If not, then our units should comply
with the new ruling. If a certified GPS position source is still required,
then we will need to continue with the certification of our GPS source.
More updates as we learn them.
-----

Since I have one of their units in one of my E-AB aircraft, next time we get some decent weather to fly, I'll try emailing <9-AWA-AFS-300-ADSB-AvionicsCheck@faa.gov (http://www.faa.gov/contact_faa/?returnPage=%40%2FW%258J%5BJ%3E6Y%25COI%3C%21E%3BM %5DBXW%3DAYE5G0H%3E%5DQ%2A2%40%5D%2A%3EF%28%24%20% 0A&mailto=H%2A3%29%5CA%28%5F4%3F%5BD%3FX%5D9%3EPN1%3D HJVPR%5BQ0EDH9%5C%216%24N%2928G8%3E%3F%3F7H%3DL72D F0%20%20%0A&subject=M77I%2EH%2A%5E%3E6%5D%5CJO%28H%23TKYKD%3D% 224AYP%28F%24H%21HU%3B%2EUKVJO%5C%26%3E74A1K%22%2F %5BPHV%2AJ%23D0%0A5K%2AJ%20%5C%24M%3E%23E%5F%3A7O% 26L6%23N0%5DI%5B1FE%26A%0A)> and see what I get back. Will report back then...

-Cub Builder

[TedK]

i had hoped the recent ADS-B rule change might permit nonTSO'd ADS-Bs to be used in Certificated Aircraft (similar to nonTSO'd AOAs) and queried the FAA. Unfortunately, that is not the case per the response I got back from the FAA. Posted below.

Ted
---------------------------------------------------

Regarding your recent inquiry (below) concerning the technical amendment of 14 CFR part 91.225:

“Would this permit a non-TSO'd ADS-B that met the "performance requirements" of the applicable TSO to be installed in a Certificated Airplane operated under Part 91?”

The ADS-B rule contained in §91.225 (as amended) does not change any existing regulatory requirement for alteration of a type certificated aircraft. An ADS-B transmitter (TSO-C166b or TSO-C154c, as applicable) installed on a type certificated aircraft through either a supplemental type-certificate or field approval must have been manufactured under an FAA production approval (TSO authorization) as required by 14 CFR §21.9(a)(2) and marked accordingly per §45.15.

Thank you for the opportunity to clarify the technical amendment to §91.225.

Regards,

James Marks
Aviation Safety Inspector (AC/AV)
ADS-B Focus Team Lead
Flight Standards Service
Avionics Branch (AFS-360)
Office (202) 267-1707 (tel:(202)%20267-1707)

[cub builder]

Re: SkyGuard, do they or don't they meet the performance specs?
-----
Since I have one of their units in one of my E-AB aircraft, next time we get some decent weather to fly, I'll try emailing <9-AWA-AFS-300-ADSB-AvionicsCheck@faa.gov (http://www.faa.gov/contact_faa/?returnPage=%40%2FW%258J%5BJ%3E6Y%25COI%3C%21E%3BM %5DBXW%3DAYE5G0H%3E%5DQ%2A2%40%5D%2A%3EF%28%24%20% 0A&mailto=H%2A3%29%5CA%28%5F4%3F%5BD%3FX%5D9%3EPN1%3D HJVPR%5BQ0EDH9%5C%216%24N%2928G8%3E%3F%3F7H%3DL72D F0%20%20%0A&subject=M77I%2EH%2A%5E%3E6%5D%5CJO%28H%23TKYKD%3D% 224AYP%28F%24H%21HU%3B%2EUKVJO%5C%26%3E74A1K%22%2F %5BPHV%2AJ%23D0%0A5K%2AJ%20%5C%24M%3E%23E%5F%3A7O% 26L6%23N0%5DI%5B1FE%26A%0A)> and see what I get back. Will report back then...


I sent a request to the FAA this weekend following a flight requesting a report on the performance of my Skyguard TWX ADS-B unit. The reply said "The report indicates there are software issues so make sure all software is up to date."

In typical FAA Fashion, the report is loaded with acronyms and numbers that seemed somewhat meaningless. They also attached a second document explaining how to read the report. My interpretation was that the Skyguard unit fails because it has no barometric altitude reporting. That seems to answer the question as to whether a pressure altitude report is required in ADS-B out. I'll post the report as a links to this post.
ADS-B report on my Skyguard TWX (http://jeffsplanes.com/KR/2013-2/SkyguardTXW%20Test%20Flight.pdf)
FAA Guide to interpreting ADS-B Avionics Check (http://jeffsplanes.com/KR/2013-2/ADS-B%20Avionics%20Check%20Results%20Guide%20BII.pdf)

-Cub Builder

[TedK]

Interesting article at AOPA with FAA Attachment (http://www.aopa.org/News-and-Video/All-News/2015/March/11/FAA-urges-LSA-makers-to-move-on-ADS-B-and-AOA).

It seems rather bizarre to me that an avionics maker can list nearly any GA aircraft on their Approvel Model List without significant engineering to ensure that the airplanes on the AML are truly compatible with the Avionics without holding any discussion with the airplane OEM, and these airplanes can be used in commercial service. But in the case of an SLSA, the avionics maker has got to mother-may-I the SLSA OEM.

Seems bass akwards to me.

Ted