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GFC500 Update


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Ok - so this is a serious limitation beyond the GFC500 - its really about the G5.  We need to know what is the failure mode of the G5 if there is a GPS failure.  Yes I think it is a good idea they are using GPS filtering in to their attitude algorithm for increased accuracy.  Why not - filtering (as in data assimilation) becomes ever more accurate the more data sources one uses.  So why not use GPS also if available?  But what is the G5's failure mode if the GPS source becomes unavailable.

Which is it:

a) The attitude reverts to AHARS only - which should be good for a good amount of time.

b) The G5 displays inop and you get zero attitude.

If it is b, then that is unacceptable and I am shocked that the FAA would allow that through certification.  But I am doubting it is b.

Then also the GFC500 autopilot which relies on the G5 would be whacked too.

However, if it is a) then this is an acceptable failure mode.  Then I would expect the GFC500 should still work, meaning straight and level, and perhaps track bearings?  At least wings level?  what do you get?  

As many of you know I have been craving and waiting for the GFC500/G5 but this would be a deal breaker.

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One of the main differences I see from going G5 rather than Aspen Max is that with the G5 I won’t have to put another GPS antenna on the top of my plane. 

I would assume Garmin has thought through the ‘what if’. 

Good question, let’s see. 

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1 minute ago, gsxrpilot said:

But it can't connect to an autopilot without the KA310... which doesn't exist yet.

Does anyone know of anyone who has installed a KI300, or are they just in stock, approved and for sale in status only on Sarasota's website? If anyone knows, Peter might. PTK, how is your installation going? I was concerned the electronic components used might have reached end of life by the mfrg. prior to delivery.

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2 hours ago, aviatoreb said:

Ok - so this is a serious limitation beyond the GFC500 - its really about the G5.  We need to know what is the failure mode of the G5 if there is a GPS failure.  Yes I think it is a good idea they are using GPS filtering in to their attitude algorithm for increased accuracy.  Why not - filtering (as in data assimilation) becomes ever more accurate the more data sources one uses.  So why not use GPS also if available?  But what is the G5's failure mode if the GPS source becomes unavailable.

Which is it:

a) The attitude reverts to AHARS only - which should be good for a good amount of time.

b) The G5 displays inop and you get zero attitude.

If it is b, then that is unacceptable and I am shocked that the FAA would allow that through certification.  But I am doubting it is b.

Then also the GFC500 autopilot which relies on the G5 would be whacked too.

However, if it is a) then this is an acceptable failure mode.  Then I would expect the GFC500 should still work, meaning straight and level, and perhaps track bearings?  At least wings level?  what do you get?  

As many of you know I have been craving and waiting for the GFC500/G5 but this would be a deal breaker.

I suspect based on the materials Garmin provided, the failure mode is similar to what happens to my Aspen GPSS when acceptable Nav signal is lost. It defaults to heading mode and the plane remains wing level. With an STEC 60 analog autopilot, I know the turn coordinator is still playing a role in maintaining wings level. I suspect the AHRS in the G5 will do the same.

Here is a video of the Aspen going into default mode. The issue on this flight was a faulty PFD/MFD throw over switch.

 

 

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4 minutes ago, Marauder said:

I suspect based on the materials Garmin provided, the failure mode is similar to what happens to my Aspen GPSS when acceptable Nav signal is lost. It defaults to heading mode and the plane remains wing level. With an STEC 60 analog autopilot, I know the turn coordinator is still playing a role in maintaining wings level. I suspect the AHRS in the G5 will do the same.

Here is a video of the Aspen going into default mode. The issue on this flight was a faulty PFD/MFD throw over switch.

 

 

According to a recent Garmin post on Beechtalk, Heading, Pitch, Alt and Vertical Speed modes all still work on the GFC 500 with a GPS failure. As far as the G5 without GPS, the unit uses pitot-static inputs to assist the attitude solution.

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22 minutes ago, gsxrpilot said:

But it can't connect to an autopilot without the KA310... which doesn't exist yet.

The BK representative on Beechtalk said that they are working with Aspen to make it an approved attitude device. That makes sense since word on the street is that the KA-310 is a re-packaged Aspen EA100. It would be nice if the AeroCruze 230 displays annunciations on the Aspens like the STEC 55 and TruTrak do.

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4 hours ago, aviatoreb said:

Ok - so this is a serious limitation beyond the GFC500 - its really about the G5.  We need to know what is the failure mode of the G5 if there is a GPS failure.  Yes I think it is a good idea they are using GPS filtering in to their attitude algorithm for increased accuracy.  Why not - filtering (as in data assimilation) becomes ever more accurate the more data sources one uses.  So why not use GPS also if available?  But what is the G5's failure mode if the GPS source becomes unavailable.

Which is it:

a) The attitude reverts to AHARS only - which should be good for a good amount of time.

b) The G5 displays inop and you get zero attitude.

If it is b, then that is unacceptable and I am shocked that the FAA would allow that through certification.  But I am doubting it is b.

Then also the GFC500 autopilot which relies on the G5 would be whacked too.

However, if it is a) then this is an acceptable failure mode.  Then I would expect the GFC500 should still work, meaning straight and level, and perhaps track bearings?  At least wings level?  what do you get?  

As many of you know I have been craving and waiting for the GFC500/G5 but this would be a deal breaker.

GPS supplies no attitude information, so I don't know how losing GPS would affect the attitude-display capability of a G5 at all.

The G5 has internal AHRS, which generally include the MEMS gyros and accelerometers, plus the pitot and static inputs.   So it has everything it needs for the basic PFD display without any input from GPS, and GPS wouldn't add any information for the attitude display, anyway.

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29 minutes ago, EricJ said:

GPS supplies no attitude information, so I don't know how losing GPS would affect the attitude-display capability of a G5 at all.

The G5 has internal AHRS, which generally include the MEMS gyros and accelerometers, plus the pitot and static inputs.   So it has everything it needs for the basic PFD display without any input from GPS, and GPS wouldn't add any information for the attitude display, anyway.

I don't know if they do so - but one COULD make a system whereby inferred computed attitude could be "filtered in" to the measured attitude from the AHARS for an even more accurate system.  This is one does in "data fusion".  I don't know if they do that.  I am just saying what one could do.  Even an inferior data source like modeled inferred attitude from GPS only computations filtered (think of a sort of averaged in) into the better AHARS source makes an even better measurement.  If this is what they are doing I would hope their code is to revert back to AHARS only.

Given the system won't track a radio source without GPS active is what makes me suspect they are doing some kind of data fusion to GPS measurements.

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Just now, aviatoreb said:

I don't know if they do so - but one COULD make a system whereby inferred computed attitude could be "filtered in" to the measured attitude from the AHARS for an even more accurate system.  This is one does in "data fusion".  I don't know if they do that.  I am just saying what one could do.  Even an inferior data source like modeled inferred attitude from GPS only computations filtered (think of a sort of averaged in) into the better AHARS source makes an even better measurement.  If this is what they are doing I would hope their code is to revert back to AHARS only.

Given the system won't track a radio source without GPS active is what makes me suspect they are doing some kind of data fusion to GPS measurements.

I'm familiar with sensor fusion, but you can't fuse a sensor input that's not there.   GPS provides position only with no attitude information.   Velocity is inferred from the change in position, which still doesn't have any attitude information.   Is your slow descent nose up clean, or nose down and dirty?   Are you slipping or coordinated?  Only the AHRS can provide that info in the G5.

I think many of these systems do perform some sensor fusion, but I don't know how much or how successfully.   It seems like that's all kept pretty proprietary, anyway, and some of it seems to not be done too well, like the Aspen red-x-ing nearly everything when the pitot information goes bad.

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12 minutes ago, aviatoreb said:

I don't know if they do so - but one COULD make a system whereby inferred computed attitude could be "filtered in" to the measured attitude from the AHARS for an even more accurate system.  This is one does in "data fusion".  I don't know if they do that.  I am just saying what one could do.  Even an inferior data source like modeled inferred attitude from GPS only computations filtered (think of a sort of averaged in) into the better AHARS source makes an even better measurement.  If this is what they are doing I would hope their code is to revert back to AHARS only.

Given the system won't track a radio source without GPS active is what makes me suspect they are doing some kind of data fusion to GPS measurements.

That's exactly what they are doing.. GPS aided first, Pitot-Static aided next, finally raw data if it loses both of those.

https://www.beechtalk.com/forums/viewtopic.php?f=21&t=131594&start=75

 

 

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8 minutes ago, EricJ said:

I'm familiar with sensor fusion, but you can't fuse a sensor input that's not there.   GPS provides position only with no attitude information.   Velocity is inferred from the change in position, which still doesn't have any attitude information.   Is your slow descent nose up clean, or nose down and dirty?   Are you slipping or coordinated?  Only the AHRS can provide that info in the G5.

I think many of these systems do perform some sensor fusion, but I don't know how much or how successfully.   It seems like that's all kept pretty proprietary, anyway, and some of it seems to not be done too well, like the Aspen red-x-ing nearly everything when the pitot information goes bad.

One can model attitude (meaning an equation best guess as to likely attitude) based on time varying observations of ground track and altitude measured from GPS, under assumptions such as coordinated flight.  Such computed attitude is inferior to a good directly measured attitude but fuse the two together intelligently and you get a new observation that is better than either separately.

In fact, in principle one can data fuse a bunch of crappy measurements to infer an over all high quality measurement.  The magic of Bayesian statistics based data fusion.

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11 minutes ago, Steve W said:

That's exactly what they are doing.. GPS aided first, Pitot-Static aided next, finally raw data if it loses both of those.

https://www.beechtalk.com/forums/viewtopic.php?f=21&t=131594&start=75

 

 

Aha!  I like these guys - they designed the device the G5 just how I would design it if I were the group design leader.

Data fusion is legit and falls under the wing of the sort of thing I do for a day job.

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Aha!  I like these guys - they designed the device the G5 just how I would design it if I were the group design leader.
Data fusion is legit and falls under the wing of the sort of thing I do for a day job.


All well and good but I find it disturbing that the devices attitude info standalone isn’t as good as a mechanical gyro, and thus requires this additional validation to work/be certified....


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Wait a minute... :)

Do electronic AIs suffer from the same goofy problems the mechanical AIs do?

They probably get a different set of goofy problems...

My mechanical AI loves to demonstrate acceleration and deceleration challenges while in the T/O run... and under braking... same in the air, but less obvious...

How disturbing is it when your mechanical gyros showed their accel/decel issues...?

You do Remember the IR Training where they explained all the shortcomings of every mechanical instrument in the panel and all the electrical systems in the plane...?

my mechanical AI could be improved by adding GPS inputs and other aides... just nobody bothered to do it...

Then again... somebody improved the TnB by reorienting the jumpy gyro and making it a TC...

Now Somebody is updating a clock and making it double as an AOAi, AI, and volt meter.... but may require some calibration...

 

What is missing...

The improvements are rather small, yet greatly appreciated...

Big G doesn’t want to have the open discussion with what they improved, why they improved it, and how it all works... at MS...

That is a tech sales guy’s job. Directed by a VP of sales...

 

wait again... Trek is their tech guy delivering the words of the sales VP.... he does it at BT... for a reason...

He used to visit MS... last brief visit here was in October...

 

My AI is one of those BK, vac powered, mechanical devices, that wears over time, and has an unknown maintenance and OH future... and requires my engine to be running, an accessory case mounted vacuum pump, and when that fails I have this giant electro mechanical device in the tail that generates another source of vacuum...

How great is that?

Maybe you guys have a more generous memory regarding your mechanical gauges... :)

Best regards,

-a-

 

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Wait a minute... 
Do electronic AIs suffer from the same goofy problems the mechanical AIs do?
They probably get a different set of goofy problems...
My mechanical AI loves to demonstrate acceleration and deceleration challenges while in the T/O run... and under braking... same in the air, but less obvious...
How disturbing is it when your mechanical gyros showed their accel/decel issues...?
You do Remember the IR Training where they explained all the shortcomings of every mechanical instrument in the panel and all the electrical systems in the plane...?
my mechanical AI could be improved by adding GPS inputs and other aides... just nobody bothered to it...
Then again... somebody improved the TnB by reorienting the gyro and making it a TC...
Now Somebody is updating a clock and making it double as an AOAi, AI, and volt meter.... but may require some calibration...
 
What is missing...
The improvements are rather small, yet greatly appreciated...
Big G doesn’t want to have the open discussion with what they improved, why they improved it, and how it all works... at MS...
That is a tech sales guy’s job. Directed by a VP of sales...
 
wait again... Trek is their tech guy delivering the words of the sales VP.... he does it at BT... for a reason...
He used to visit MS... last brief visit here was in October...
 
My AI is one of those BK, vac powered, mechanical devices, that wears over time, and has an unknown maintenance and OH future...
 
Maybe you guys have a more generous memory regarding your mechanical gauges... 
Best regards,
-a-
 


Perhaps but my king kfc150/ki256 combo won’t disconnect on an ILS because of GPS interference...


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gs,  ( I added some more above during the editing process...)

 

I expect my KAP to disconnect when one of its servo motors slips a clutch or has some simple wear challenge...

My AI is one of those BK, vac powered, mechanical devices, that wears over time, and has an unknown maintenance and OH future... and requires my engine to be running, an accessory case mounted vacuum pump, and when that fails I have this giant electro mechanical device in the tail that generates another source of vacuum... delivered by a hose that has been known to send chemicals up towards the instruments...  (MS pics of large PVC hose going from the tail to the instruments up front... older Os have a nice rubber hose for vacuum delivery...

How great is that?

:)

-a-

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gs,  ( I added some more above during the editing process...)
 
I expect my KAP to disconnect when one of its servo motors slips a clutch or has some simple wear challenge...

My AI is one of those BK, vac powered, mechanical devices, that wears over time, and has an unknown maintenance and OH future... and requires my engine to be running, an accessory case mounted vacuum pump, and when that fails I have this giant electro mechanical device in the tail that generates another source of vacuum...

How great is that?

-a-



It’s not great which is why I’m evaluating replacements and plan to ditch vacuum pumps. Having your AI rely that heavily on an easily jammed constellation of satellites isn’t a step forward imho. I don’t see why they can’t come up with a device that can be certified without that input, based on my knowledge of electronics and physics.


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46 minutes ago, gsengle said:

 


All well and good but I find it disturbing that the devices attitude info standalone isn’t as good as a mechanical gyro, and thus requires this additional validation to work/be certified....


Sent from my iPhone using Tapatalk

 

Who said it’s not as good as a stand alone mechanical?  It may we’ll be better than a stand alone mechanical as a stand alone ahars and better yet still when filtering in gps info.  Could be... I don’t know the specs.  But guessing on what could be done and also what today’s faa expects - I would guess this is the case.

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For Long Body Mooney owner who is not in immediate need of an autopilot and insists on Garmin I'd wait for the GFC600 - much better autopilot. I bet that ends up on the list down the road. If a Bonanza gets it why not eventually a Bravo or Ovation?

http://www.aviationconsumer.com/issues/49_9/avionicsreport/Garmins-New-Autopilots-Flawless-Performers_7111-1.html

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