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ADSB GPS for IFR flight

Veetail88

Well Known Member
Maybe this has been discussed here before, but I don't recall reading anything about it, but I'm wondering if the new WAAS GPS units being sold by Dynon and UAvionics and such for ADSB can be used for legal IFR navigation?

I'm guessing that the answer is no, because they are not a part of a "certified" GPS "navigator", but it seems to me that if they are accurate enough for ADSB that maybe they are for IFR. No? Again, probably a different certification standard but I'm just wondering.

I also understand that the moving map and control function of any of the EFIS systems (other than the certified Dynon and Garmin units) are also not certified for IFR use, but hey? Just curious.
 
ADS-B for IFR

If your ADS-B out solution is legal for VFR it is legal for IFR.
My RV-7A has Dynon's ADS-B In and Out and I plan to fly it IFR.
And I'm putting the uAvionics on my Piper Cherokee and it is an IFR platform.
Only ADS-B out units not legal for IFR are also not legal for VFR and they are the dash board (not installed) solutions, but I can't even think of one anymore.
There is no requirement for ADS-B In. And this is currently only a USA requirement.
 
I'm gonna jump out with NO straight out of the gate.

A WAAS position indicating unit is ONLY good for the ADS-B mandate.
ADS-B out only, such as 330ES, is perfectly legal in rules airspace with a compliant position source, like a 430W.

Your navigator must be IFR certified, and need not be WAAS.

Two uses of similar technology.
 
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I'm gonna jump out with NO straight out of the gate.

A WAAS position indicating unit is ONLY good for the ADS-B mandate.
ADS-B out only, such as 330ES, is perfectly legal in rules airspace with a compliant position source, like a 430W.

Your navigator must be IFR certified, and need not be WAAS.

Two uses of similar technology.

I always thought that the 430non-WAAS navigator was not certified or IFR flight, but the WAAS version is.

Either way, I suspect you’re correct about the WAAS GPS ADSB receivers not usable as a certified source receivers for IFR flight, but I would think if they meet standards to keep airplanes from crashing into each other that they should be accurate enough to fly IFR with. Coupled with an EFIS for display of course; at least in E/AB aircraft.
 
There’s a lot more that goes into IFR certification than just GPS position accuracy, particularly on error detection and correction, but there are other differences too. Also the non-WAAS 430/530 is IFR certified but limited to enroute nav and basic LNAV approaches. Also it can’t be used for sole source nav and there’s more restrictive alternate selection criteria than for a WAAS box.
 
In addition to the gps, the TSO has a lot of requirements on the database. For example, approaches must be in the database - the pilot may not enter lat-long by hand. None of the new GPS boxes designed for ADSB have a database containing approaches, so using one will require ?marrying it? to a database.
 
The non-WAAS GPS is IFR legal... Just not as a sole source, it requires a VOR or other nav source as well. Therefore, the 430 is legal as it has both sources in one unit.

I always thought that the 430non-WAAS navigator was not certified or IFR flight, but the WAAS version is.
 
We need to pay a little closer attention to terminology, because the devil is in the details of this terminology.

That little GPS device that feeds position to your EFIS and/or your ADSB-Out device is what is referred to as a GPS SENSOR.

The panel mount 430 or similar is referred to as a GPS NAVIGATOR.

There's a world of difference between a Sensor and a Navigator.

A Sensor provides position/rate/time information to other systems.

A Navigator often contains a Sensor, and uses its position/rate/time information in combination with a navigation database to produce a flight guidance solution to allow us to navigate between pre-defined points contained in the database.

The IFR question is really easy to answer... Since a SENSOR doesn't have an approved IFR database, it cannot be used for IFR navigation. If another device in the aircraft has an approved IFR navigation database and uses the SENSOR data, then it may be capable of IFR navigation - this is a common configuration in transport-category aircraft where the GPS sensor feeds its data to a Flight Management System. There is another current thread here on VAF discussing this topic, specific to GRT's plan to use its WAAS GPS Sensor along with a database in its EFIS to produce IFR navigation capability. It would do so on a demonstrated capability basis, not on the basis of having been certified as a TSO-compliant GPS navigator. There is some reasonable debate as to the legality of doing this and the probability of success doing this.

So, coming back to the original question... the answer is a simple NO - your ADSB position source, if it is solely a GPS sensor, is not capable of being used for IFR navigation. Unless you have an FMS or similar approved IFR navigation device to which that sensor feeds its data, again the answer is likely a simple no. If you want to use your EFIS as an IFR navigator using GPS sensor input, it's on you to demonstrate that your solution meets the minimum operational performance specs of the equivalent GPS navigator TSO, be that TSO 126 or TSO 145.
 
gps ifr

So for example
I installed Dynon's GPS sensor (antenna) that has WAAS and it feeds position to the transponder for ADS-B out and that is legal ADS-B out for IFR flights. But that senors (antenna's) position is also fed to the Dynon EFIS which does have maps, but is not TSOed so it is not legal for IFR /G. So I also installed a Garmin 430. It has a separate antenna and that unit makes flying IFR /G legal. I can also drive the Dynon EFIS with the Garmin 430 GPS position and that is legal IFR and I can use the approach plates in the Dynon EFIS for plates, but the 430 is doing to the work, not the Dynon sensor. Do they match yes. Could I practically use just Dynon yes, but not legal.

However, now I see Dynon is getting their HDX box legal to install into Production Planes like Beech V35. I wonder if that will make the GPS side of Dynon's system legal for IFR /G?
 
So for example
I installed Dynon's GPS sensor (antenna) that has WAAS and it feeds position to the transponder for ADS-B out and that is legal ADS-B out for IFR flights. But that senors (antenna's) position is also fed to the Dynon EFIS which does have maps, but is not TSOed so it is not legal for IFR /G. So I also installed a Garmin 430. It has a separate antenna and that unit makes flying IFR /G legal. I can also drive the Dynon EFIS with the Garmin 430 GPS position and that is legal IFR and I can use the approach plates in the Dynon EFIS for plates, but the 430 is doing to the work, not the Dynon sensor. Do they match yes. Could I practically use just Dynon yes, but not legal.

However, now I see Dynon is getting their HDX box legal to install into Production Planes like Beech V35. I wonder if that will make the GPS side of Dynon's system legal for IFR /G?
Again the answer is no. There is a whole lot more than having maps to be a GPS navigator. The difference in requirements and certification between a simple GPS position source and GPS navigator is huge ($$$$) and something no experimental company can afford.

:cool:
 
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Well thanks for all the information guys. I pretty much knew the question was a pretty complex and regulated one, but I hadn't seen anything about the particulars. Again, I can count on the brain trust here for information.

All that said, if I were to end up doing something really stupid and ending up in the soup, you can bet your backside I'll be using the "not certified" IFR capabilities in my AFS 4500 and GPS puck to save my bacon!

Thanks again!
 
The difference in requirements and certification between a simple GPS position source and GPS navigator is huge ($$$$) and something no experimental company can afford.

:cool:

Well Dynon can afford it or at least their owner can. Question is does he think it is a good investment or not?
 
So for example
However, now I see Dynon is getting their HDX box legal to install into Production Planes like Beech V35. I wonder if that will make the GPS side of Dynon's system legal for IFR /G?

The HDX is becoming legal to install in certificated aircraft. It is not certified as a NAVIGATOR but rather as an INDICATOR to replace ASI, ALT, VSI, DG etc. It's installed as a Primary Flight Display, not a navigator. They're two totally different things.
 
...All that said, if I were to end up doing something really stupid and ending up in the soup, you can bet your backside I'll be using the "not certified" IFR capabilities in my AFS 4500 and GPS puck to save my bacon!..

In that case ihat's an emergency so you're legally ok to use whatever means you have to get out of it as you see fit so use EVERYTHING including your iPad, iPhone, handheld GPS , use everything !
 
Another way to think about this is the ADSB WAAS sensor is just like your iPhone and the Map app. It shows where you are exactly.

The IFR, TSO'd Navigator is like having a super fancy Waze app or the Map directions app, but a lot more specific in that it's 4D (lat, long, altitude, speed and time) and compares that 4D with a certified database to provide IFR track/path guidance via specific course deviation indicators and annunciation capability (track, path, reduced signal, etc). The annunciation feedbacks provide QA and SA to the pilot (where are they, where are they going, how does that compare to the procedure). The database is a big deal as it has pilot selectable approaches that are validated and not easily susceptible to pilot data entry errors, etc. The VFR moving map with a course line drawn on it is no where near as assured / validated / standardized enough to provide performance assurance to navigate in the IFR system. If it were, well, it would probably be TSO'd.

The navigator "uses" position data to put a stake in the ground but then earns it's keep by going to work. Accurate position is required, but non WAAS is still accurate enough for high minimum, non-precision approaches, because the navigator is still working hard to provide all the quantified guidance in the proper format still. There are higher mins associated with a non WAAS navigator but it can be IFR.
 
Another way to think about this is the ADSB WAAS sensor is just like your iPhone and the Map app. It shows where you are exactly.

The IFR, TSO'd Navigator is like having a super fancy Waze app or the Map directions app, but a lot more specific in that it's 4D (lat, long, altitude, speed and time) and compares that 4D with a certified database to provide IFR track/path guidance via specific course deviation indicators and annunciation capability (track, path, reduced signal, etc). The annunciation feedbacks provide QA and SA to the pilot (where are they, where are they going, how does that compare to the procedure). The database is a big deal as it has pilot selectable approaches that are validated and not easily susceptible to pilot data entry errors, etc. The VFR moving map with a course line drawn on it is no where near as assured / validated / standardized enough to provide performance assurance to navigate in the IFR system. If it were, well, it would probably be TSO'd.

The navigator "uses" position data to put a stake in the ground but then earns it's keep by going to work. Accurate position is required, but non WAAS is still accurate enough for high minimum, non-precision approaches, because the navigator is still working hard to provide all the quantified guidance in the proper format still. There are higher mins associated with a non WAAS navigator but it can be IFR.

Good analogy !
 
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