What else besides Garmin for WAAS IFR GPS ?

[BobTurner]

Originally Posted by az_gila

Question for Dynon....

The above statements seem to say that use of a Dynon unit to provide Altitude Encoding may not be legal for IFR flight if a TSO is truly needed...

Gil,

FAR 91.217 says the altimeter must meet TSO standards OR pass the usual biennial transponder test. (b) OR (c) in the regs. I do believe our Canadian friends don't have this choice.

[az_gila]

Originally Posted by BobTurner

Gil,

FAR 91.217 says the altimeter must meet TSO standards OR pass the usual biennial transponder test. (b) OR (c) in the regs. I do believe our Canadian friends don't have this choice.

But isn't the altitude encoding data also a part of the IFR navigation boxes and the previous text talks about the "system" being TSO?

[az_gila]

Originally Posted by dynonsupport

Gil,
Not sure what the above has to do with altitude encoding in a transponder.

Dynon has a statement of compliance for altitude encoding. Note that ADS-B REQUIRES the same altitude encoder to be used for the transponder and ADS-B OUT data.

......

91.217(b) says that as long as your encoder is the same data as your altimeter (not a blind encoder) that's all you need. No TSO's or other data needed.

ADS-B transmits both pressure and geometric (GPS) altitude. The GPS altitude must come from a compliant device, the pressure must come from the same place as the transponder.

Same as above reply.

Isn't the altitude data part of an IFR system? I'm referencing IFR requirements from your earlier post, not the panel display of altitude or ADS-B....

[dynonsupport]

Gil,
I think a lot of things are being mixed up when it comes to altitude, and I'm not 100% sure which reg you are quoting for "IFR altitude".

1) There is pressure altitude for the transponder, from you static system.

2) There is indicated altitude for the pilot, which is #1 corrected for baro.

3) There is geometric altitude from the GPS, use for ADS-B and for IFR approaches.

A GPS NEVER encodes altitude for the transponder. That's illegal. It must be pressure altitude off a static port, not geometric altitude from a GPS.

#1 and #2 are tested with the bi-annual check required by 91.411. No mention of a TSO there, just the check.

#3 requires a device meeting the TSO.

[az_gila]

Originally Posted by dynonsupport

Gil,
I think a lot of things are being mixed up when it comes to altitude, and I'm not 100% sure which reg you are quoting for "IFR altitude".

1) There is pressure altitude for the transponder, from you static system.

2) There is indicated altitude for the pilot, which is #1 corrected for baro.

3) There is geometric altitude from the GPS, use for ADS-B and for IFR approaches.

A GPS NEVER encodes altitude for the transponder. That's illegal. It must be pressure altitude off a static port, not geometric altitude from a GPS.

#1 and #2 are tested with the bi-annual check required by 91.411. No mention of a TSO there, just the check.

#3 requires a device meeting the TSO.

I might be mistaken (it happens a lot.......) but isn't the altitude data that is fed into the GPS IFR navigators part of the failure detection system for GPS accuracy?

The 430 IM talks about the baro altitude data input being part of RAIM calculations.

That sounds like a part of an IFR system and should be a TSO source per your earlier posting on TSO and IFR systems.

[dynonsupport]

The Garmin GNS non-W install manuals don't say anything about the requirements for the altitude source, just that one is used for RAIM (which is not required) and non-precision VNAV. It's clearly meant to be hooked to your altitude encoder. If the FAA will let you use an altimeter for primary reference in IFR and for your transponder encoding, I see nothing that says it can't be used as a reference here.

Remember, TSO'd devices are TSO'd when installed as described. In an experimental, they're hooked to a non-certified electrical system, but that doesn't de-certify them because the manual doesn't say "hook to a certified electrical system" it says "here are the power requirements." In this case, it just says how to hook it up, not what needs to be on the other end.

The GNS-W (WASS) products don't do RAIM. RAIM died when we switched to augmented GPS. The 430W does use altitude for "Advisory VNAV" - which if you ignore, you will use your altimeter for, which has the same source...

[az_gila]

Originally Posted by dynonsupport

The Garmin GNS non-W install manuals don't say anything about the requirements for the altitude source, just that one is used for RAIM (which is not required) and non-precision VNAV. It's clearly meant to be hooked to your altitude encoder. If the FAA will let you use an altimeter for primary reference in IFR and for your transponder encoding, I see nothing that says it can't be used as a reference here.

Remember, TSO'd devices are TSO'd when installed as described. In an experimental, they're hooked to a non-certified electrical system, but that doesn't de-certify them because the manual doesn't say "hook to a certified electrical system" it says "here are the power requirements." In this case, it just says how to hook it up, not what needs to be on the other end.

The GNS-W (WASS) products don't do RAIM. RAIM died when we switched to augmented GPS. The 430W does use altitude for "Advisory VNAV" - which if you ignore, you will use your altimeter for, which has the same source...

Thanks for the clarification...