Question about IFR requirements

[Marc Zeitlin]

That still leaves him without a legal navigation source. The GNX375 is not approved for IFR use in certificated aircraft.

It most certainly is. See:

https://buy.garmin.com/en-US/US/p/577174

Last paragraph on the page says:

"With installation approval available for hundreds of Part 23 Class I/II aircraft models, adding a GNX 375 navigator to your cockpit is a straightforward, all-bases-covered proposition."

[FlyingRon]

It can be "installed" in certified planes. It's still not approved as the sole means of IFR nav.

[Marc Zeitlin]

It can be "installed" in certified planes. It's still not approved as the sole means of IFR nav.

How so?

14CFR Part 91.205(d)(2) USED to say:

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

but the current version says:

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

So the requirement for ADF/VOR or any other GROUND based navigational equipment doesn't exist - an approved enroute and approach GPS (which the 175 / 355 /375 family is) is adequate to be legal. Obviously, only GPS approaches can be flown, but there is no longer any requirement for other IFR navigational equipment. This version of 91.205 apparently went into effect on 8/30/2017.

Did you have some other regulation in mind?

[FlyingRon]

Because unlike VORs and ADFs, certificated planes need appropriate TSO approval for IFR use even for enroute and terminal (let alone approaches). The GNX does not have this. The FAA relented on the units like the GNX being used for the ADS-B requirement but not anything else. This is not a sole-means IFR navigator.

[martymayes]

Flight manual supplement says GNX 375 is approved for stand alone IFR navigation, specifically:

"Single engine piston aircraft under 6,000 lbs. maximum takeoff weight:
Required Equipment for IFR operations utilizing GPS navigation: Single GPS
175/GNC 355/GNX 375 Navigator"

All other aircraft require:
"second source of TSO-C146 approved GPS navigation or a separate source of VHF navigation"

That's good enough for me.

[geosnooker2000]

Sooo... Add a GNX375, and then anything else I want to really use that does not require telescopic glasses to see from 3 feet away (like a Garmin G3X)? I really don't understand how people can actually use something with that small of a display as far as map display.

[FlyingRon]

It's not intended to be used as such, it just gets a small display so it can fit into a "transponder-sized" piece of real estate. They expect you'll use it to drive something else.

[geosnooker2000]

Thank you for the explanation. It's not always easy getting info on stuff that seasoned pilots already know and take for granted that us newbes don't know! Cheers!

[martymayes]

Sooo... Add a GNX375, and then anything else I want to really use that does not require telescopic glasses to see from 3 feet away (like a Garmin G3X)? I really don't understand how people can actually use something with that small of a display as far as map display.

I fly a plane with an 375 and since I'm one of the few pilots that does not use an ipad when flying lightplanes, I use the screen. Seems to work okay for me and that's with tri-focal correction. I can't imagine a younger fella having to struggle due to screen size.

[geosnooker2000]

Well... I'm 52, so...