Homebuilt IFR Equipment

Has anyone successfully and legally documented their own equipment for IFR use?

The local airports have VOR/DME approaches. I do not have a TSO'd DME nor a TSO'd GPS. I do have a built-in GPS in my Grand Rapids Sport. Can I use this GPS as a DME? It does give me distance To/From and travel time to a VOR.

If I can how would I document it?

I seriously doubt that GPS distance could be legally used for a DME approach. If you shot the approach as a VOR/DME with DME inop minimums (if shown on the approach plate), then the GPS data would be helpful but nothing more. Actually, I'm not even sure you could legally shoot a VOR/DME if a DME unit is not installed.
John

I fly as /G in the T-34. What we are taught is that one still has to have the equipment to tune the approach requested (ie you can't fly an "NDB approach" using your GPS soley), but you may use a certified GPS to fix any point, airport, or navaide on any chart or approach plate as long as it comes from the data base... (you can't manually enter lat/longs in a certified GPS and use those points for IFR navigation).

The idea is that if you request an approach you are equipped for it, but use all the stuff you have available to fix your self on the approach the best you can...

IFR requires TSO's equipment...

For IFR you need an approved (TSO'd) equipment - or proof that the equipment meets all TSO requirements - which are quite technical regarding design and performance. Unless you literally built the equipment, you don't have access to the design info needed to document TSO compliance (manufacturers don't publish that info), and there is a LOT$ of equipment needed to do the testing.

An IFR GPS can substitute for DME, unless the approach plate says otherwise.

In order to fly an approach, you need the equipment in the title of the approach. If the approach says (only) NDB, you need an NDB. Many approaches also have GPS overlays, so they say 'NDB or GPS'.

The bottom line is that a non-approved GPS is excellent supplementary situational awareness for IFR, but can't be used legally as primary navigation for flying in IMC.

DGlaeser said:

For IFR you need an approved (TSO'd) equipment - or proof that the equipment meets all TSO requirements....

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This is not necessarily true. Not all equipment in the aircraft must be built under a TSO authorization, although in some cases it makes some sense to use "TSOed" equipment. There is an article published on the EAA website talking about this issue. I encourage all EAA members to click on the following link and read the article. (NOTE: the lastest edit of this article will post to the web site later today - October 29th)

http://members.eaa.org/home/homebuilders/faq/Equipping a Homebuilt for IFR operations.html#TopOfPage

Cheers!

Joe

Joe, thanks for the pointer to that article. I take issue with one part, though:

?Two-way radio communications system and navigational equipment appropriate to the ground facilities to be used.?

This statement tells us that our primary navigational equipment must be based on ground facilities (primarily VOR). As this is the case, a homebuilt with only a GPS installed would not be legal for IFR operations.

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I don't read that statement from the FAA to mean that primary navigational equipment must be based on ground facilities. It just says that if you're using ground facilities for navigation, you need to have the appropriate equipment to use them. Right?

-Rob

RV10Rob said:

I don't read that statement from the FAA to mean that primary navigational equipment must be based on ground facilities. It just says that if you're using ground facilities for navigation, you need to have the appropriate equipment to use them. Right?

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I have seen that exact point debated countless times on the Internet and in hangar discussions over the past few years, and it (the interpretation) seems to depend totally on where you place the accent, and how you parse the sentence. It's not an "experimental" versus "certified" debate either - the sentence applies to all IFR airplanes. I have even seen different FSDO interpretations, so I think it is still a bit unsettled. It can be argued that the GPS has a ground element essential to the operation of the system.....

My opinion? It was written before the days of GPS, and therefore, the writer assumed that all navigation systems were ground based, as they wee at the time. It is simply a case of technology outrunning the regulators, and as such, is obsolete - but until it is changed, it is still "the rule" (however you want to interpret it).

Paul

The EAA article really over-simplifies...

jnorris said:

This is not necessarily true. Not all equipment in the aircraft must be built under a TSO authorization, although in some cases it makes some sense to use "TSOed" equipment. There is an article published on the EAA website talking about this issue. I encourage all EAA members to click on the following link and read the article. (NOTE: the lastest edit of this article will post to the web site later today - October 29th)

http://members.eaa.org/home/homebuilders/faq/Equipping a Homebuilt for IFR operations.html#TopOfPage

Cheers!

Joe

Click to expand...

...compliance with the TSO requirements for GPS navigation equipment.

---- from the EAA article ---

As with transponders and other equipment discussed previously, GPS equipment must meet the performance requirements of the applicable TSO (in this case, C129), but there is no specific requirement for the equipment to be built under a TSO authorization. However, if the equipment is not built under a TSO authorization, it is up to the owner/operator to verify and document that the equipment performs within the required specifications. It is also the owner or operator's responsibility to document the necessary flight-test data showing that the installation performs within the required accuracy parameters.


No way will a flight test prove compliance. Just the items listed in the TSO that depend on software compliance alone would negate a flight test.

As the previous post said, I would encourage you to read the actual TSO and see if you could even come close to saying that your non-TSO GPS even came close.... just a few pages should do...

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/e560cd9c6acf8ba186256dc700717e0f/$FILE/C129a.pdf

And for IFR GPS equipment, the compliance to the specifications of this TSO is not optional - the FARs mandate it.

RV10Rob said:

Joe, thanks for the pointer to that article. I take issue with one part, though....

Click to expand...

Rob,

You didn't wait until my latest edit has posted to the web!! That verbiage has been deleted from the regulation all together (and thus that section has been deleted from the article). The new version of 91.205 says:

"Two-way radio communication and navigation equipment suitable for the route to be flown."

Note that the reference to "ground based" systems has been removed.

This is why I noted in my original post to wait until my updated article was posted to the web later today.

Cheers!

Joe

az_gila said:

No way will a flight test prove compliance. Just the items listed in the TSO that depend on software compliance alone would negate a flight test.

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Hi Gil,

Read the entire paragraph you quoted again. It doesn't say that a flight test would prove compliance with the TSO. It says the flight test would verify accuracy. The sentence before that states that it would be up to the owner/operator to document compliance with the appropriate standard. The two sentences are separate. In no way does it say that a flight test alone will prove compliance with TSO requirements.

Cheers!

Joe

jnorris said:

Hi Gil,

Read the entire paragraph you quoted again. It doesn't say that a flight test would prove compliance with the TSO. It says the flight test would verify accuracy. The sentence before that states that it would be up to the owner/operator to document compliance with the appropriate standard. The two sentences are separate. In no way does it say that a flight test alone will prove compliance with TSO requirements.

Cheers!

Joe

Click to expand...

Do I read this to say that I can legally fly my -9 with only the Garmin 496 installed, if I do some flight testing and document it?

(Not that I would, as I'm a VFR only kind of guy.)

Yes You Can - Maybe

I have a SL-60 and no DME. I fly VOR DME approaches. There is an FAA interpretation from that says certain GPS receivers can be used for the DME function. I am only concerned about my legality so I only know that mine is included you will have to check on yours.

It is an added complication to flying the approach because you must determine the exact point where the GPS reading you are using corresponds with the the required DME reading and keep it straight. If the approach guidance VOR is on the field it is fairly straight forward but if is not then you must use the sum of the distance to the runway numbers to each fix to determine step down points etc. I write these sums directly on the approach plates to avoid mental mathematics at the most stressful time during the IFR flight.

Bob Axsom

Bob Axsom said:

I write these sums directly on the approach plates to avoid mental mathematics at the most stressful time during the IFR flight.

Bob Axsom

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Very good advice! I do that as well if I am using the GPS as a sub. Live math is hard enought but to try it while under the IMC gun, could cost you!

OK...

jnorris said:

Hi Gil,

Read the entire paragraph you quoted again. It doesn't say that a flight test would prove compliance with the TSO. It says the flight test would verify accuracy. The sentence before that states that it would be up to the owner/operator to document compliance with the appropriate standard. The two sentences are separate. In no way does it say that a flight test alone will prove compliance with TSO requirements.

Cheers!

Joe

Click to expand...

...sorry for the mis-read...

But, that would make it even harder (just about impossible) for any regular home builder to "document compliance with the appropriate standard".

Why not just come out and say directly that a GPS system must be TSO'd for use under IFR? - if used as a primary navigation function, not a situational awareness function.

The whole article leads readers on and implies that you could do the documentation yourself. Again, I say read a few sections of the actual TSO C-129 I linked to previously and ask yourself "can I honestly document that my 496 (or any other non-TSO GPS system) meets the requirements"?.

The FAA has nicely limited the amount of equipment that must be TSO'd (or documented to the TSO requirements) for our Experimentals - it's easier to just buy that equipment, especially for something as important as IFR flight.

I still say the article is an over-simplification.

Hi Gil,

az_gila said:

...sorry for the mis-read...

Click to expand...

No problem. Been there, done that myself more than once!!

az_gila said:

But, that would make it even harder (just about impossible) for any regular home builder to "document compliance with the appropriate standard".

Click to expand...

Agreed. The article does not mean to imply that any of this would be easy, or even doable. But it would be legal if the person wanted to go through the effort.

az_gila said:

Why not just come out and say directly that a GPS system must be TSO'd for use under IFR? - if used as a primary navigation function, not a situational awareness function.

Click to expand...

Because if the article said that we'd have a bunch of people writing and calling, telling us that the article is not accurately stating what is legal and what is not! This happens all the time to us here at EAA HQ. There are a fair number of folks who read our publications and then go to great lengths to take issue with anything that is not absolutely accurate. This is not a bad thing, but trying to satisfy those folks leads us to situations like this discussion, where what is technically legal does not necessarily make a lot of sense. It really can be a "no win" situation sometimes when posting and publishing info. Everyone has their own opinion on what we should say and how we should say it. Bottom line: We do the best, most accurate job we can and deal with the feedback as it comes.

az_gila said:

Again, I say read a few sections of the actual TSO C-129 I linked to previously and ask yourself "can I honestly document that my 496 (or any other non-TSO GPS system) meets the requirements"?.

Click to expand...

I agree. I don't think anyone could do it, and I don't recommend anyone actually go to the effort of trying. In fact, I have some doubt that you could actually meet the requirements of the TSO with a 496. But if anyone really would like to try it, they're welcome to!

az_gila said:

The FAA has nicely limited the amount of equipment that must be TSO'd (or documented to the TSO requirements) for our Experimentals - it's easier to just buy that equipment, especially for something as important as IFR flight.

Click to expand...

Amen to that! I totally agree. And that's exactly the way 99.9% of the people do it. It's by far the most economical way to equip the aircraft. And that is mentioned in the article.

az_gila said:

I still say the article is an over-simplification.

Click to expand...

That may be the case, and you're certainly welcome to that opinion. But the article is technically accurate, as far as we are able to determine. I hope most find it to be informative and useful.

Cheers!

Joe

I'll second that!

Bob Axsom said:

I write these sums directly on the approach plates to avoid mental mathematics at the most stressful time during the IFR flight.

Click to expand...

Several years ago an acquaintance of mine flew a perfectly good A-36 into a hill while flying an ILS approach. The approach plate stated in large type "ADF REQUIRED" The Bonanza did not have an ADF installed. The pilot did have a Garmin 196 that was found in the wreckage. Since the only time you would need an ADF on this procedure was for the missed approach, my theory is that he setup the LOM, the first fix on the miss, in the 196. Add to this the lack of DME on the localizer and you have a potential for disaster. The airplane hit a hill 9 miles from the airport. My hunch is that he was reading the GPS distance as "DME" to the airport when it was to the LOM 5 miles east of the airport. That profile would put you into the terrain.

John Clark
RV8 N18U "Sunshine"
KSBA

Thanks for the reply...

jnorris said:

..... big snip .....

Agreed. The article does not mean to imply that any of this would be easy, or even doable. But it would be legal if the person wanted to go through the effort.

......

That may be the case, and you're certainly welcome to that opinion. But the article is technically accurate, as far as we are able to determine. I hope most find it to be informative and useful.

Cheers!

Joe

Click to expand...

...Joe.

I'll agree that the article is technically accurate, however I think you should have actually expanded what is needed to be done by your members to meet the "technical accuracy" suggested in the article.

I would say that this lack of conclusion and a lack of actual practical steps needed by a builder is the "over simplification" I refer to.

Legalities need to be followed with practicalities - Isn't that the real spirit of EAA Experimental aircraft building?

...but thanks for an interesting discussion...

Practical steps...

az_gila said:

what is needed to be done by your members to meet the "technical accuracy" suggested in the article.

Click to expand...

I would like to see that.

I have a RV-6 with a TSO'd IFR GPS in the panel, along with the required placement of CDI, annunciator lights, buttons, etc. The operating limitations contains the appropriate statement. However the builder didn't get around to doing any flight tests of the installation and placarded the GPS "not for IFR".

So, what do I need to do to legally use this equipment for enroute and terminal IFR? Verify all points in paragraphs 22 and 23 of FAA Advisory Circular 20-138A (installed performance ground and flight tests), and make a logbook entry, and remove the placard; or...?

--Paul

Garage Guy said:

So, what do I need to do to legally use this equipment for enroute and terminal IFR? Verify all points in paragraphs 22 and 23 of FAA Advisory Circular 20-138A (installed performance ground and flight tests), and make a logbook entry, and remove the placard; or...?

Click to expand...

Or, for enroute navigation, just go. I noticed an unusual trend with ATC a few weeks ago while flying 3 different IFR legs in my -8. My avionics are very basic, a KX-125 Nav/Com for basic enroute VOR navigation and a Garmin 296 for, umm... situational awareness. I file as /U, meaning Mode C transponder and no DME. Just a VOR; no GPS, no FMC, no nuthin', listed right there on the flight plan. However, once airborne and on my way, ATC kept giving me clearances to intersections and fixes down the road. Not to VORs, but to points along the airways and arrival routes. I guess controllers these days just assume that most IFR traffic has RNAV capability and either overlook or ignore the /U for aircraft equipment. I'm not about to do approaches with a 296, but if a controller gives me a shortcut to a downline enroute fix, I'm not gonna argue about it, I just go direct. Seems to make things easier for both of us.

Now, if the controllers would just pay attention to the "no SIDS, no STARS" note in the comments section and quit clearing me via the Leona 6 Departure or the Riice 2 Arrival...

Can be substituted

johngoodman said:

I seriously doubt that GPS distance could be legally used for a DME approach. If you shot the approach as a VOR/DME with DME inop minimums (if shown on the approach plate), then the GPS data would be helpful but nothing more. Actually, I'm not even sure you could legally shoot a VOR/DME if a DME unit is not installed.
John

Click to expand...

I seem to remember reading in the FARs or AIM that GPS can be substituted for DME and/or ADF (ADF I'm sure about). From a practical standpoint it is more accurate than either.

Also on the DME issue, regarding a departure proceedure negotiation with ATC at KVGT, in 2005:
Proceedure called for DME. I had been out of flying for 10 years, so I didn't really have any GPS experience. I didn't have a DME so I didn't think I could fly the departure. The controller asked if I had a GPS in the panel. The answer was yes, and a moment later I had my clearance.