Help me understand modern avionics

[radioguy01]

Hi all,

I'm in the very early phases of daydreaming about buying a plane, and of course already daydreaming of upgrading the avionics. And I'm already seeing the dollar signs go out the window.

That said, I'm having a little trouble understanding retrofit glass cockpits, like the Aspen Evolution 2500, or Dynon's Skyview. It appears that these units still need a GPS box to drive that portion of them.

So it looks like they are the PFD and MFD, but for the GPS function you have to hook it up to something like the Garmin 430. Is that correct? No "built in" GPS for $25,000?

And I see people with double stacked Garmin GPS's, is that for redundancy? Do both turn on and run while flying and you would just switch to the backup if the primary failed?

Also, how do all of these different devices talk to each other? Is there a standardized protocol?

Thank you

 

[cdahl]

I'm in the very early phases of daydreaming about buying a plane, and of course already daydreaming of upgrading the avionics. And I'm already seeing the dollar signs go out the window

Try to find your dream plane with all or most of the updated avionics already done.....let the previous owner take the finanical beating!!

 

[poadeleted20]

That said, I'm having a little trouble understanding retrofit glass cockpits, like the Aspen Evolution 2500, or Dynon's Skyview. It appears that these units still need a GPS box to drive that portion of them.

So it looks like they are the PFD and MFD, but for the GPS function you have to hook it up to something like the Garmin 430. Is that correct? No "built in" GPS for $25,000?

The systems about which you are asking are purely display systems, with no transmitters or receivers (comm or nav) included. Even the G1000 integrated flight deck has separate boxes behind the panel which provide those radio functions. The only hidden boxes that come with something like the Garmin G500 retrofittable display system are those which directly support the display itself, like the AHRS and ADC, video processors, etc. The retrofittable systems rely on external radios like a Garmin GNS/GTN GPS/nav/comm plus GTX transponder to provide those other functions.

And I see people with double stacked Garmin GPS's, is that for redundancy? Do both turn on and run while flying and you would just switch to the backup if the primary failed?

Pretty much so, just like "classic" instrument/radio packages. There may still be times when you're using both nav or comm radios simultaneously (like when flying an approach with cross-radial step-down fixes, or monitoring 121.5 as required by FDC NOTAM while talking to CTAF or ATC), but the second nav/comm/GPS is mostly for backup. Note that when you have something like a GNS/GTN, all your comm, nav, and GPS eggs rely on a single power supply basket, so one fried component can leave you deaf, dumb and blind for IFR operations. That's why single radio IFR is not very popular.

Also, how do all of these different devices talk to each other? Is there a standardized protocol?

Yes, but don't ask me to explain it.

As for why this all costs so much, that's driven by the staggering costs of certification (a process which takes years) spread over only a limited market.