What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Attitude indicator/ADAHRS, how many do you need for IFR..

Walt

Walt

Well Known Member
After reading the chilling account of the Lancair accident in this months Sport Aviation I though I would throw out what I think is sufficent redundancy for real IFR. A single back up is not good enough as you still don't have a tie breaker so 3 always visible attitude indicators is the only real way to know which way is up.

Even though my G3X has 2 ADAHRS one could fail and not flag itself so its possible that you would continue to operate on a failed unit (like the poor Lancair soul did) without knowing there's a problem, so I'm not sure the dual ADAHRS buys you anything in that situation.

The Sandia Quattro 340 below is a very nice unit as the attitude indicator does not rely on either air data (which is normally present) or GPS to function reliably so it's a truly independent instrument with its own battery back up as well. (the Sandia was already slated for the spot it occupies before the G5 was announced)

The G5 in addition to performing back up functions adds some really nice features to the G3X system so I'm really enjoying it.

So between the G3X, G5 and Sandia I think I got my attitude covered :D

IMG_7672-1200.jpg
 
Last edited:
Walt - I agree you do need a tie breaker if you stick your head in the clouds. Without it you very well could loose control while trying to figure out which display is the good one. My solution to the problem is dual Skyview screens and Adahars, a Dynon D1, and a Flightstream 210 feeding an Ipad mini. The flightstream was selected to make the Garmin 430W a little easier to use as well as the additional benefit of an independent adahars source feeding the Ipad synthetic vision. The D1 gives me an additional independent adahars source as well as its own display. I am aware that my solution provides only GPS based altitude and airspeed for the redundant equipment. I don't do 200 and 1/2 approaches anymore because no one is paying me, so I just wait a bit until the weather suits my needs. I am contemplating however changing out the D1 for a G5 one of these days as I do like that unit better.

I was surprised at your use of the Sandia unit. At $3,500 that's quite an expensive backup for the capability I would think. Wouldn't another G5 installed stand alone and not connected to the network accomplish the same thing or even perhaps a Dynon D2? I'm not critiquing your install just trying to understand your thoughts on the subject.
 
Walt,
are you forgetting your partial panel training? Just refer to your DG or compass. If youre also turning, trust the AI that agrees with the turn.
 
partial panel and insidious horizon failure

Walt, lots of ways to look at it. Sandia is expensive and certified. GRT mini has an AHRS and one third the cost.
Also, some autopilots like Trio have AHRS. If the wings are level.... and the attitude indicator goes offline... the plane doesn't care. More and more though... the EFIS is driving the servos also. That could be a problem in a cloud if it begins an uncommanded roll. But, as mentioned... there are simpler partial panel ways to determine if you are level.
 
Perhaps I made the incorrect assumption that everyone has already received and read their copy of EAA Sport Aviation. For those that have not the scenario went something like this:

Well equipped Lancair IV turboprop with 3000 hr IFR rated pilot.
Takeoff with 1000 ft ceiling, cleared to 12K, almost immediately after TO controller noticed aircraft off course, controller calls and pilot acknowledges and turns back on course. About 1.5 min later aircraft is off course again and this time when controller calls he gets no response. Aircraft climbs to 6K feet in a right turn then enters a diving right turn and crashes. Entire flight is 5 minutes.

The aircraft was equipped with back up attitude, airspeed, alt in the center of the panel.

Investigation revealed that the magnetometer failed and was giving the PFD (certified glass panel equipment) bogus info which caused the PFD to display erroneous information, but the pilot did not recognize the failure of the PFD because it still appeared to be working normally with no indication of failure.

So how many folks think they could recognize then analyze this situation with their current glass panel and not end up in the same situation?
 
Last edited:
Walt said:
So how many folks think they could recognize then analyze this situation with their current glass panel and not end up in the same situation?
Click to expand...

That's the reason I have two magnetometers and two AHRS attached to my pfd and mfd. they alert if they don't match. I have a third EFIS from a different manufacturer that tells me which one is correct.

I suspect there is a small possibility that I could end up with three different indications.
 
Walt said:
After reading the chilling account of the Lancair accident in this months Sport Aviation I though I would throw out what I think is sufficent redundancy for real IFR. A single back up is not good enough as you still don't have a tie breaker so 3 always visible attitude indicators is the only real way to know which way is up.

Even though my G3X has 2 ADAHRS one could fail and not flag itself so its possible that you would continue to operate on a failed unit (like the poor Lancair soul did) without knowing there's a problem, so I'm not sure the dual ADAHRS buys you anything in that situation.

The Sandia Quattro 340 below is a very nice unit as the attitude indicator does not rely on either air data (which is normally present) or GPS to function reliably so it's a truly independent instrument with its own battery back up as well.

So between the G3X, G5 and Sandia I think I got my attitude covered :D
Click to expand...

Walt,

Thanks for sharing your thinking on this. There is plenty of good backup going on in your RV.

We wanted to point out some advantages of your dual ADAHRS G3X system which others may not be aware.

  1. The G3X system performs attitude miscompare monitoring when two or more ADAHRS units are installed, so a MISCOMP alert on your PFD is a warning that the system has automatically detected that there is significant disagreement between the ADAHRS units.

    Increased fault tolerance and miscompare monitoring are the primary advantages of having dual ADAHRS. Even if you are not monitoring the output of the second ADAHRS, the system is and will let you know if you should perform a manual comparison against the backup instrument to determine which ADAHRS to use on the primary PFD (and by the autopilot).

  2. For a dual display, dual ADAHRS system such as yours, a reversion switch can come in handy on the MFD. With a simple flip of a switch you can display both ADAHRS solutions side-by-side making it easy to compare the G5 attitude with ADAHRS1 and ADAHRS2. The default ADAHRS source selection for PFD1 and MFD1 is ADAHRS1 using the AUTO selection, but you can flip the reversion switch and manually select ADAHRS2 to the MFD before you launch into IFR so that it is immediately displayed when the reversion switch is flipped, or just leave the ADAHRS source selection to AUTO and manually select either ADAHRS1 or ADAHRS2 to either display if you so choose. After selecting the backup ADAHRS for the second display, you can take it out of reversion and use it as a MFD knowing that it is ready to be used as an additional attitude display if you need it.
Thanks,
Steve
 
Jrskygod said:
I was surprised at your use of the Sandia unit. At $3,500 that's quite an expensive backup for the capability I would think. Wouldn't another G5 installed stand alone and not connected to the network accomplish the same thing or even perhaps a Dynon D2? I'm not critiquing your install just trying to understand your thoughts on the subject.
Click to expand...

I really like the display on the Sandia, it fit in the space/3.25" hole I had and the fact that it non GPS based as well as not dependent on the air data for attitude info. Expensive, yes (street price $3295) but definitely a quality unit. This was slated for that spot even before the G5 was announced, when the G5 came out well I just had to find another spot for it!

Graham D said:
Walt,
are you forgetting your partial panel training? Just refer to your DG or compass. If youre also turning, trust the AI that agrees with the turn.
Click to expand...

I think in this scenario the "DG" or HSI is this case would match the turn of the attitude indicator.

rleffler said:
That's the reason I have two magnetometers and two AHRS attached to my pfd and mfd. they alert if they don't match. I have a third EFIS from a different manufacturer that tells me which one is correct.

I suspect there is a small possibility that I could end up with three different indications.
Click to expand...

Sounds like a good solution but I guess the question here is how quickly could you sort out a similar scenario if it occurred?
 
Last edited:
g3xpert said:
Walt,

Thanks for sharing your thinking on this. There is plenty of good backup going on in your RV.

We wanted to point out some advantages of your dual ADAHRS G3X system which others may not be aware.

  1. The G3X system performs attitude miscompare monitoring when two or more ADAHRS units are installed, so a MISCOMP alert on your PFD is a warning that the system has automatically detected that there is significant disagreement between the ADAHRS units.

    Increased fault tolerance and miscompare monitoring are the primary advantages of having dual ADAHRS. Even if you are not monitoring the output of the second ADAHRS, the system is and will let you know if you should perform a manual comparison against the backup instrument to determine which ADAHRS to use on the primary PFD (and by the autopilot).

  2. For a dual display, dual ADAHRS system such as yours, a reversion switch can come in handy on the MFD. With a simple flip of a switch you can display both ADAHRS solutions side-by-side making it easy to compare the G5 attitude with ADAHRS1 and ADAHRS2. The default ADAHRS source selection for PFD1 and MFD1 is ADAHRS1 using the AUTO selection, but you can flip the reversion switch and manually select ADAHRS2 to the MFD before you launch into IFR so that it is immediately displayed when the reversion switch is flipped, or just leave the ADAHRS source selection to AUTO and manually select either ADAHRS1 or ADAHRS2 to either display if you so choose. After selecting the backup ADAHRS for the second display, you can take it out of reversion and use it as a MFD knowing that it is ready to be used as an additional attitude display if you need it.
Thanks,
Steve
Click to expand...

Great info Steve as usual, thanks for sharing!

I do have the reversion switch just to the right of the MFD but never thought to switch the MFD to default to ADAHRS 2 so it's immediately available when you throw the switch. In the past I have just left it in auto.

Another question for you, if the magnetometer soft failed like it did in the Lancair accident aircraft how would you know? With only a single magnetometer there's nothing to compare it to.
 
I love it

I spent many hundreds of hours teaching the various adoptees how to use synthetic vision and AHRS as the chief pilot for Chelton. No one had ever flown IFR this way before. NASA envisioned the technique... and put the idea in the public domain. It was many years before anyone wrote the code and invented the processors to actually do it. Also, why it is not patented by any one manufacturer.
I observed many things. One odd one was the brains reliance on backup analog gauges in the peripheral vision. Only covering the instruments could break the natural tendency to attend to them. (without consciously knowing it BTW)
Another observation is the subtle shift away from what we always taught as the "scan". With a modern PFD... most data is in your central field of view. Our scan skills are eroding. As alluded to in your comments, and indicated directly... in the Lancair crash, a failing instrument may not be recognized.
So, to answer your first posted question... I would suggest that it may be less important to have many alternate boxes to show which way is up... and more important to discipline yourself to constantly scan for discrepancies.
And the Sandia is top rate hardware. Have been to the factory. Know the inventors... and am really impressed. No GPS needed... but for that matter the GRT does not rely on the GPS solution for roll and pitch, nor does the Trio autopilot head. The Garmin folks rested behind the scenes while Chelton obtained the first AML certification for glass. Some tax dollars applied through Capstone phase two helped.... Garmin then jumped both into the fixed wing and helo markets and pushed the envelope into photo realism on the Synthetic Vision. And good for them! Costs went down, performance went up by leaps and bounds and the end user... you and me get actual market competition. Now that... is the AMERICAN way. Cheers and safe flight in IMC Walt. It is a cool time to be in the avionics business.
 
Last edited:
G5 - G3x Single ADAHRS

Is the G5 coupled to the G3X ADAHRS in a single ADHRS installation.... or does the built-in G5 attitude and heading come form the G5 itself... and is this good for a manual crosscheck?
 
g3xpert said:
For a dual display, dual ADAHRS system such as yours, a reversion switch can come in handy on the MFD. With a simple flip of a switch you can display both ADAHRS solutions side-by-side making it easy to compare the G5 attitude with ADAHRS1 and ADAHRS2. The default ADAHRS source selection for PFD1 and MFD1 is ADAHRS1 using the AUTO selection, but you can flip the reversion switch and manually select ADAHRS2 to the MFD before you launch into IFR so that it is immediately displayed when the reversion switch is flipped, or just leave the ADAHRS source selection to AUTO and manually select either ADAHRS1 or ADAHRS2 to either display if you so choose. After selecting the backup ADAHRS for the second display, you can take it out of reversion and use it as a MFD knowing that it is ready to be used as an additional attitude display if you need it.

Thanks,
Steve
Click to expand...

And there is also a touch button that can be enabled on the MFD to switch from PFD to MFD with the touch of that button. No physical switch required to make it think it is a PFD so you can force what ADAHRS is being used.

I have and use them both (PFD/MFD touch button and reversion switch) for different ways to run the screens depending on who is in the right seat or what I want to do with that second screen.

I really is handy to be able to have the G5 with its own ADAHRS, PFD on ADAHRS1 and MFD running as a PFD on ADAHRS2. Super easy to compare them all in that setup.
 
sibriggs said:
Is the G5 coupled to the G3X ADAHRS in a single ADHRS installation.... or does the built-in G5 attitude and heading come form the G5 itself... and is this good for a manual crosscheck?
Click to expand...

The G5 displays its own ADAHRS data. The heading comes from the G3X system. If that is not available it shows Ground TRK.

The G5 can provide ADAHRS data to the G3X screens in the event that all actual G3X ADAHRS(s) fail.

The G5 makes a great tie breaker for a dual ADAHRS G3X system and provides several types of redundancy to the system as a bonus.
 
Thanks, I took this quote form the G5 news release and if confirms that?

" In the unlikely event of a G3X ADAHRS failure, the G5 doubles as a redundant ADAHRS source, which can supply the appropriate air data, attitude and heading information to G3X displays. "

With a G5 why would one need dual ADAHRS?
 
Walt said:
I really like the display on the Sandia, it fit in the space/3.25" hole I had and the fact that it non GPS based as well as not dependent on the air data for attitude info.
Click to expand...

It is my understanding that the G5 also has the ability to run without air data or it can also run without GPS available. The understanding is that the attitude aiding works best when those are available but it can run without them....

Here is the blurb from the manual:

"The G5 will also use GPS and airspeed data to provide the most accurate attitude
information. If none of these additional sources of information are available, attitude
calculations will still be valid but accuracy may be slightly affected."
 
sibriggs said:
Thanks, I took this quote form the G5 news release and if confirms that?

" In the unlikely event of a G3X ADAHRS failure, the G5 doubles as a redundant ADAHRS source, which can supply the appropriate air data, attitude and heading information to G3X displays. "

With a G5 why would one need dual ADAHRS?
Click to expand...

For the exact reason Walt is mentioning in the original post. As a tie breaker.

Also, the miscompare monitoring feature Steve mentioned above does not apply to the G5 and the G3X system with one ADAHRS. The G3X system only performs miscompare monitoring on actual G3X ADAHRS units like the GSU73 and GSU25 and you need at least 2 of them for that to function.
 
flightlogic said:
I observed many things. One odd one was the brains reliance on backup analog gauges in the peripheral vision. Only covering the instruments could break the natural tendency to attend to them. (without consciously knowing it BTW).
Click to expand...

My own experience mirrors this. I used steam as backups for my glass and the steam was placed such that it was easily within an old style scan.

1) I had a "hard time" transitioning to glass
2) I still do not like the tapes for ASI and Alt as much as the round dials.
3) When my glass failed in IFR, I had little trouble moving back to the steam gages.

I think the three together are a direct indication that I am still using the steam in peripheral vision. I have not gone to the effort to cover them up yet.
 
Walt said:
Great info Steve as usual, thanks for sharing!

I do have the reversion switch just to the right of the MFD but never thought to switch the MFD to default to ADAHRS 2 so it's immediately available when you throw the switch. In the past I have just left it in auto.

Another question for you, if the magnetometer soft failed like it did in the Lancair accident aircraft how would you know? With only a single magnetometer there's nothing to compare it to.
Click to expand...

Hello Walt,

First, the G5 uses GPS and air data (in that order), when available, to improve the accuracy of the attitude data, but doesn't use heading at all, so it can't be affected by a bad magnetometer. As indicated in the manual, the G5 will provide attitude information even in the absence of GPS and air data.

This is just another way that the G5 was made dissimilar to the other ADAHRS units in a G3X system.

The 3 axis magnetic field data from a single GMU22 magnetometer is provided to each of the ADAHRS in a G3X system, and each ADAHRS performs an independent heading determination based on this data.

As anyone knows who has installed a G3X system with the magnetometer in a less than ideal location, the system quite readily recognizes and flags the presence of a magnetic anomaly (magnetic field that can't be produced by the earth), and when this happens the GSU25 ADAHRS units which use magnetometer data go into no-mag mode operation and cease using the magnetometer data in the attitude solution.

Due to the sophistication of the invalid magnetic field detection algorithms, it is very unlikely that bad mag data could affect the attitude solution. Again, since the G5 flight instrument never uses magnetometer data in the attitude solution, this is just one additional safeguard in your G5 equipped system.

As a side note, we have had a few customers ask us to stop displaying the mag anomaly message on the information page because they feel the heading is operating just fine and there is no need for the mag anomaly notification. While we appreciate that this can seem like a nuisance message, it not only provides indication that the magnetometer installation could be improved, but is also showing that the primary GSU25 ADAHRS units distrust the calculated heading and are operating without one of the 3 methods used in aiding the attitude solution.

Thanks,
Steve
 
Last edited:
Backup for ADAHRS

I've flown needle ball and airspeed in actual on more than one occation when I had a gyro failure in the past, so, I feel that a G3X and G5 with a single ADAHRS and an ipad is plenty of backup for me. I rather have another engine than more technology in the cockpit as backup. Engine failure risk is much higher than Garmin technology failijng. :)
 
So the G5, Skyview and the G3X use air data (pitot and static) for the attitude display but will still display reasonably accurate attitude if air data is not available. But what happens to the attitude display if the air data is available but is not accurate - for instance blocked static or blocked/leaking pitot line.

Some time ago I did an approach in heavy rain and the pitch display on my Skyview intermittently rapidly oscillated + - (unusable) which I believe was due to water intermittently blocking the static port. Fortunately I also had a MGL Mini Extreme which does not use air data for attitude and it was rock solid.

I now have the single Skyview, the Xtreme, Trio and also the Sandia as our regulator in Australia wants TSO for IFR.

FIN
9A
 
My initial post on this issue was re enforced by flight logic. The lancair accident may have been different from an adequate scan. Just watching a computer screen isn't good enough. I agree with Walt that his linked HSI may have agreed with his failed AH but I know when I am on departure on a black night or in IMC in a turbine with Glass, I am always cross checking alt and heading with the back up gauges or even the neglected compass that no one seems to look at these days. There is no need for all this triple redundancy ****, just old fashion airmanship. If youre flying in a straight line, chances are your wings are level
 
I firmly believe that a set of simple analog gauges that is not tied to the electrical system is far better redundancy for IFR flying. Right before I built my panel, I was set on two different/brand EIFS for redundancy and then I read a report of a plane with full electrical panel to crash in an IFR due to electrical melt down. My panel design changed to have a set of analog gauges and I am much happier this way.
 
Finley Atherton said:
So the G5, Skyview and the G3X use air data (pitot and static) for the attitude display but will still display reasonably accurate attitude if air data is not available. But what happens to the attitude display if the air data is available but is not accurate - for instance blocked static or blocked/leaking pitot line.

Some time ago I did an approach in heavy rain and the pitch display on my Skyview intermittently rapidly oscillated + - (unusable) which I believe was due to water intermittently blocking the static port. Fortunately I also had a MGL Mini Extreme which does not use air data for attitude and it was rock solid.

I now have the single Skyview, the Xtreme, Trio and also the Sandia as our regulator in Australia wants TSO for IFR.

FIN
9A
Click to expand...

Hello Fin,

Good question and this was taken into account when developing the Garmin G5 Flight Instrument. While it is true that under some circumstances the G5 will use air data to improve the precision of the attitude solution, it will not use air data whatsoever (to improve the precision of the attitude solution) unless GPS data is not available for this purpose.

This is another aspect of the G5 that distinguishes it from most other ADAHRS units. As long as the G5 is receiving data from either its internal GPS or several types of external GPS units (G3X/GNS/GTN/GPS20A), the G5 attitude solution is insulated from the impacts of blocked pitot and static ports.

Thanks,
Steve
 
Last edited:
g3xpert said:
Hello Fin,

Good question and this was taken into account when developing the Garmin G5 Flight Instrument. While it is true that under some circumstances the G5 will use air data to improve the precision of the attitude solution, it will not use air data whatsoever unless GPS data is not available for this purpose.
Click to expand...

I am confused by this. If the G5 does not use air data then is the speed displayed air speed or ground speed and is the altitude Baro or GPS? :confused:
 
GalinHdz said:
I am confused by this. If the G5 does not use air data then is the speed displayed air speed or ground speed and is the altitude Baro or GPS? :confused:
Click to expand...

Re-read the whole sentence. If GPS is available then air data is not used to compute attitude.
 
g3 Expert said:
This is another aspect of the G5 that distinguishes it from most other ADAHRS units. As long as the G5 is receiving data from either its internal GPS or several types of external GPS units (G3X/GNS/GTN/GPS20A), the G5 attitude solution is insulated from the impacts of blocked pitot and static ports.
Click to expand...
How well does it fare when it doesn't have access to either?

I'm considering installing a G5 as a backup, but don't particularly want to tap into the pitot/static lines if I can help it. By the same token I'd rather not have a GPS antenna parked on the glareshield for it if it will let me keep right side up without either of these elements.
 
KRviator said:
How well does it fare when it doesn't have access to either?

I'm considering installing a G5 as a backup, but don't particularly want to tap into the pitot/static lines if I can help it. By the same token I'd rather not have a GPS antenna parked on the glareshield for it if it will let me keep right side up without either of these elements.
Click to expand...

Hello KRviator,

Yes, as you probably know, the G5 air data sensors may be turned off if you do not wish to connect pitot/static lines. You may also turn off the GPS and GPS data fields if you do not wish to use the internal GPS to display GPS ground speed, altitude, and track.

Even when the G5 has neither airspeed nor GPS to improve the accuracy of the attitude solution, it does not have any inherent inaccuracies that a mechanical gyro based attitude indicator doesn't have.

Thanks,
Steve
 
GalinHdz said:
I am confused by this. If the G5 does not use air data then is the speed displayed air speed or ground speed and is the altitude Baro or GPS? :confused:
Click to expand...

Hello Galin,

This statement is referring to the use of air data to improve the precision of the attitude solution. Air data is only used for this purpose when GPS data is not available to eliminate the possibility of a blocked pitot/static from affecting the attitude solution (when GPS data is available).

If the G5 is installed with pitot/static connections, the airspeed, baro altitude, and vertical speed is all air data derived, not GPS.

Thanks,
Steve
 
Agree with Walt

I also believe in redundant systems by different manufacturere's just so I don't happen to have a failure or hit the same software bug at the same time. I have dual AFS 5400's with a Dynon D-10 in the panel as well as a Trutrack Sorcerer autopilot. I am still not fond of integrated autopilots due to the potential to not have it when you might need it the most.

BTW my philosophy has paid off now. On a trip in an RV-7A that had just been upgraded from Chelton's to G3X screens we had the screens fail multiple times in IMC while climbing through an 8K' thick layer. We were solid IMC. Having the Sorcerer and the D-10 made it no problem. Yes, we hit a bug that was locking up the Garmin screens when loading the flight plan changes from ATC via the IPAD. After 3 failures and waiting for them to reboot I figured out what the new owner was doing and had him stop making changes. Once on top in VFR we duplicated the problem, as I wanted to know for sure before we started back down.

[ed. Re-reading this thread after awhile. Thought....Vic, did you loose ALL screens in IMC simultaneously or did you loose one or the other with the info moving to the remaining? I may be reading this wrong, but I interpretted what you wrote as you lost all screens at once. I had one EFIS reboot due to bad cooling on my part, and the info all moved over to the screen that had good cooling (very hot day with plane outside a long time). Just curious, and thanks in advance.

v/r,dr]
​

BTW there is also a good story about the software in the F-22's, some of the most tested s/w ever put in an airplane. On a deployment to Japan while crossing the International dateline all of the screens went dark, so the story goes. Luckily they were with a tanker to bring them back to Hawai.

Vic
 
Last edited by a moderator:
vic syracuse said:
I am still not fond of integrated autopilots due to the potential to not have it when you might need it the most.
Vic
Click to expand...

I would love to see the statistical odds of this happening with a properly installed and configured dual screen, dual ADAHRS G3X System that includes a G5 and GMC30?.

While I also fully understand the benefits of having a working AP in IMC, I also don't personally consider it mission critical equipment in a plane that has proper redundancy built into the panel. One ponders how many hours have been flown in real IMC in planes that have no AP?
 
Brantel said:
I would love to see the statistical odds of this happening with a properly installed and configured dual screen, dual ADAHRS G3X System that includes a G5 and GMC30?.

While I also fully understand the benefits of having a working AP in IMC, I also don't personally consider it mission critical equipment in a plane that has proper redundancy built into the panel. One ponders how many hours have been flown in real IMC in planes that have no AP?
Click to expand...

I agree with Vic. If the PFD goes dark for whatever reason, I find it reassuring that I can reach over to the AP head and quickly ensure that the wings are level and I'm maintaining altitude.

I will also admit that the amount of risk is small. I have see about a half a dozen times various vendor's PFDs reboot in flight. Fortunately for me, they've all been during VFR conditions.

I admit that I'm not familiar with the G3X, since my screens from another vendor were installed before the G3X was available. If the PFD the servos are attached fails, is there a mechanism that allows the MFD to take over control?
 
Nice panel.

In addition to a backup to the glass, I also choose to not use potentially debilitating substances when I fly, especially IFR. Being aware of what effects medication might have on your ability to fly is perhaps more fundamental to safe flight (VMC or IMC) than what's in the panel.

From the NTSB:
However, it is likely that diphenhydramine, which impairs cognitive and psychomotor performance, diminished the pilot's ability to recognize and manage the erroneous PFD indications.
Click to expand...

NTSB Link
 
rleffler said:
I admit that I'm not familiar with the G3X, since my screens from another vendor were installed before the G3X was available. If the PFD the servos are attached fails, is there a mechanism that allows the MFD to take over control?
Click to expand...

Yes if the PFD fails, the MFD automatically turns itself into the PFD and takes over. This is called the reversionary mode in Garmin terms.

As well...if a system also includes a G5 and the PFD and the MFD both fail, it will take over control of the AP automatically as long as there is a GMC 30? installed with the system.

The G5 is a game changer for the G3X system since it has the ability to basically act as a stand alone AP when paired with a GMC 30? when the primary G3X AP controlling systems fail (it can also be installed as a totally stand alone AP)... It serves triple duty as a backup PFD/ ADAHRS and GPS as well.
 
Last edited:
re "So between the G3X, G5 and Sandia I think I got my attitude covered"

Sound conclusion based on knowledge of 3 sound systems.

However when the chips are down in hard IFR, there has to be a way of a particular system ALERTING the pilot when it is at fault. There is no time to determine which system is at fault, the failure has to be ID'ed immediately. Any use of a failed data to control the flight will not end well.

When I worked for a living, this was of concern as it is today. Systems were simpler and vey reliable but if a failure occurred, out would pop a fail flag. There was no ambiguity and there was a means of switching to a good system.

Do the G3X, G5 and Sandia systems have internal failure monitoring? Will the pilot know without question a failure has occurred?
 
David-aviator said:
Do the G3X, G5 and Sandia systems have internal failure monitoring? Will the pilot know without question a failure has occurred?
Click to expand...

While it is impossible for a system's watchdogs to catch everything, the G3X and the G5 will flag invalid indications with a big red X if it detects issues with the source of the information.

35kmwqr.png


wsu5fr.png
 
Last edited:
first time i've ever seen it, but yesterday in flight my PFD showed the attitude fail x for a brief moment, the AP disconnected- very strange because in the past when AHRS anomalies were detected, AHRS2 would simply be used- seamlessly, i need to contact g3xpert and figure out why it caused a panic mode of sorts this time
 
BobTurner said:
Re-read the whole sentence. If GPS is available then air data is not used to compute attitude.
Click to expand...
OK, but that wasn't my question.

g3xpert said:
If the G5 is installed with pitot/static connections, the airspeed, baro altitude, and vertical speed is all air data derived, not GPS
Click to expand...
THANKS! That is what I wanted to know. When connected to a pitot/static system it displays air data derived airspeed, baro altitude and VS. THAT is what I want in a backup system. I was concerned it used GPS derived speed/altitude, only using air data to improve GPS data and during GPS failures. The G5 is an actual full backup EFIS for any system, not just a Garmin. :cool:
 
Last edited:
David-aviator said:
re "So between the G3X, G5 and Sandia I think I got my attitude covered"

Sound conclusion based on knowledge of 3 sound systems.

However when the chips are down in hard IFR, there has to be a way of a particular system ALERTING the pilot when it is at fault. There is no time to determine which system is at fault, the failure has to be ID'ed immediately. Any use of a failed data to control the flight will not end well.

When I worked for a living, this was of concern as it is today. Systems were simpler and vey reliable but if a failure occurred, out would pop a fail flag. There was no ambiguity and there was a means of switching to a good system.

Do the G3X, G5 and Sandia systems have internal failure monitoring? Will the pilot know without question a failure has occurred?
Click to expand...

Yes they all have there own system failure monitoring, but... it's not the hard failure that worries me as those are generally easy to flag (red X) it's the soft incipient failure that can bite you (like the accident aircraft).

Being that we don't have a triple redunant system available that uses comparitors for monitoring them we have to use our brains. So for me having 3 seperate attitiude/air data displays directly in front of me makes it relatively easy to spot a system that does not agree with the other two.

I think if we had a triple ADAHRS system that actually "voted" we would have a more fault tolerant system, but right now to the best of my knowledge, I don't believe that's available for us. The pilot has to sort out which system(s) are or are not working.
 
Last edited:
Walt said:
I think if we had a triple ADAHRS system that actually "voted" we would have a more fault tolerant system, but right now to the best of my knowledge, I don't thinks that's available for us. The pilot has to sort out which system(s) are or are not working.
Click to expand...

There may be a technical limitation on why the G5 is not included in the miscompare monitoring. Trying to compare a panel mounted ADAHRS with a rigidly mounted strap down ADAHRS may prove problematic.
 
Brantel said:
There may be a technical limitation on why the G5 is not included in the miscompare monitoring. Trying to compare a panel mounted ADAHRS with a rigidly mounted strap down ADAHRS may prove problematic.
Click to expand...

Yes but even if we had 3 GSU25's installed which the G3X will support, to my understanding (G3X team please correct me if I'm wrong), we still wouldn't have a system capable of figuring out which ADAHRS doesn't match the other two and lock that bad unit out, it's still up to the pilot to do the comparison and decide which ADAHRS is not performing correctly and then manually select the right one. A 'miscomp" message only tells you that you that they don't match and you need to look at it and figure it out yourself.
 
Walt said:
Yes but even if we had 3 GSU25's installed which the G3X will support, to my understanding (G3X team please correct me if I'm wrong), we still wouldn't have a system capable of figuring out which ADAHRS doesn't match the other two and lock that bad unit out, it's still up to the pilot to do the comparison and decide which ADAHRS is not performing correctly and then manually select the right one. A 'miscomp" message only tells you that you that they don't match and you need to look at it and figure it out yourself.
Click to expand...

You are correct, I may have misunderstood. It is up to the pilot to decide which to trust...
 
Brantel said:
You are correct, I may have misunderstood. It is up to the pilot to decide which to trust...
Click to expand...

Yep. It was the same with steam gauges. Sometimes a failure of the pitot/static system could take a while to sort out. With glass it is certainly getting a little more complicated, and it's only as good as the code, which is constantly improving.

That's why I like a separate autopilot. Gives me time "look at my watch" and sort things out. Granted the odds are low, as someone mentioned earlier, but if you fly long enough you learn that it's all about stacking the odds in your favor as much as possible.

Vic
 
Auto-Pilot

I read in one of the notes about not flying in actual IFR without an AP. Here's a different thought.

Hand flying is like your car driving. Once you've got enough miles under your belt you sub conscious mind takes over the tasks involved and you can continue to control the vehicle/plane while sharing your attention with other issues.

Remember when as a new teenage driver you almost ran off the road changing the station on the radio. Now I bet you can drive down the road while reading something. (not smart but I bet you can do it).

Well, hand flying in actual weather for enough hours will get you the same ability to control the aircraft under all conditions while handling different distractions. I think the number of hours is probably somewhere greater than 100 actual IFR without autopilot.

I couldn't afford an autopilot in an Apache I owned. I flew over 300 hrs in actual conditions with all the missed approaches, holding patterns and distractions involved, some of it using only needle ball and airspeed. It got a lot easier as I passed the 100hr point.

While it's reassuring to have redundant backup technology, it's more reassuring to know you can fly the aircraft in any situation.

Just some food for thought.

Steve
 
I'll keep this short to avoid unnecessary thread drift.

I agree with a piece of your assessment. Mainly that large amounts of time in actual plus recency breeds proficiency. I also don't buy into the "IMC without an AP is suicide" mentality.

That said...comparing it to driving doesn't pass the sniff test. Hand flying in true IMC conditions for durations of time is physiologically demanding on a level most pilots may never understand. Maybe you are just exceptional, and I'll applaud you for it and admit I'm jealous.

All that said...when your having a bad day...or disorientation kicks in without warning...you can't step on the brakes and pull off the side of the Victor airway to take a break.



sibriggs said:
I read in one of the notes about not flying in actual IFR without an AP. Here's a different thought.

Hand flying is like your car driving. Once you've got enough miles under your belt you sub conscious mind takes over the tasks involved and you can continue to control the vehicle/plane while sharing your attention with other issues.

Remember when as a new teenage driver you almost ran off the road changing the station on the radio. Now I bet you can drive down the road while reading something. (not smart but I bet you can do it).

Well, hand flying in actual weather for enough hours will get you the same ability to control the aircraft under all conditions while handling different distractions. I think the number of hours is probably somewhere greater than 100 actual IFR without autopilot.

I couldn't afford an autopilot in an Apache I owned. I flew over 300 hrs in actual conditions with all the missed approaches, holding patterns and distractions involved, some of it using only needle ball and airspeed. It got a lot easier as I passed the 100hr point.

While it's reassuring to have redundant backup technology, it's more reassuring to know you can fly the aircraft in any situation.

Just some food for thought.

Steve
Click to expand...
 
I don't think flying without an autopilot is suicide, as many of us hand flew in IMC for many years before autopilots started to get affordable for the lower end GA market, and especially the Amateur-built world. Without starting a war, I would point out that the amateur-built aircraft we fly now do not have near the stability of the the certified aircraft. Of course, that's what makes them so much fun to fly!
While a C-182 or others might have some very positive stability that carries over to IMC flying, the RV's do not. You really do have to stay on top of them, and for a long length of time it can be very tiring without an autopilot. Couple that with trying to load an approach or a complicated clearance in bumpy conditions and things can go south in quite a hurry.

Again, an autopilot is not required, but it sure is an enabler for a less stressful flight. And unless you are really proficient in IMC I would recommend you only tackle going up or down through thin layers if possible until you gain experience and proficiency in the type of aircraft you are flying.

The neat thing about RV's is that they are very capable cross-country airplanes, so every once in a while you may need the skills and equipment to go up or down through a layer. That's the way we primarily use the capabilities in the 10. After all, we really like flying so we can sight see. If we absolutely have to get there on a schedule we use the Airlines (although that is not always reliable at times).

Vic
 
vic syracuse said:
I don't think flying without an autopilot is suicide, as many of us hand flew in IMC for many years before autopilots started to get affordable for the lower end GA market, and especially the Amateur-built world. Without starting a war, I would point out that the amateur-built aircraft we fly now do not have near the stability of the the certified aircraft. Of course, that's what makes them so much fun to fly!
While a C-182 or others might have some very positive stability that carries over to IMC flying, the RV's do not. You really do have to stay on top of them, and for a long length of time it can be very tiring without an autopilot. Couple that with trying to load an approach or a complicated clearance in bumpy conditions and things can go south in quite a hurry.

Again, an autopilot is not required, but it sure is an enabler for a less stressful flight. And unless you are really proficient in IMC I would recommend you only tackle going up or down through thin layers if possible until you gain experience and proficiency in the type of aircraft you are flying.

The neat thing about RV's is that they are very capable cross-country airplanes, so every once in a while you may need the skills and equipment to go up or down through a layer. That's the way we primarily use the capabilities in the 10. After all, we really like flying so we can sight see. If we absolutely have to get there on a schedule we use the Airlines (although that is not always reliable at times).

Vic
Click to expand...

Well said Vic.

I flew part 141 single engine charters without auto pilot before it was mandated for such flights..it can be a hand full as anyone who has done it knows.

At this point in my life, I like the auto pilot flying VFR. I am not IFR equipped but I do have tracking and altitude hold, it is very nice. :)
 
You can get proficient without an autopilot flying hard IFR in a high performance airplane but it takes a lot of time and attention. A few of those in a day and you'd swear you'd been on a chain gang instead. I've flown hundreds of hard IFR hours single pilot in twin Cessna's without A/P's and it's certainly doable but I've also flown dozens of NDB approaches in mountains to minimums and I'd much rather sit behind synthetic glass and have a good autopilot do the hard work so I could sit back and monitor the situation. There are no end of stories of guys getting distracted by bad information and flying it into the ground. Having an autopilot doesn't stop that but it does give you one more chance to catch it before it kills you. This day and age, they are so cheap, it doesn't make sense to fly IFR without one. My passengers are worth more to me than the few thousand bucks it costs to put one into an experimental.
 
BrentCameron said:
You can get proficient without an autopilot flying hard IFR in a high performance airplane but it takes a lot of time and attention. A few of those in a day and you'd swear you'd been on a chain gang instead. I've flown hundreds of hard IFR hours single pilot in twin Cessna's without A/P's and it's certainly doable but I've also flown dozens of NDB approaches in mountains to minimums and I'd much rather sit behind synthetic glass and have a good autopilot do the hard work so I could sit back and monitor the situation. There are no end of stories of guys getting distracted by bad information and flying it into the ground. Having an autopilot doesn't stop that but it does give you one more chance to catch it before it kills you. This day and age, they are so cheap, it doesn't make sense to fly IFR without one. My passengers are worth more to me than the few thousand bucks it costs to put one into an experimental.
Click to expand...

Yes, I agree completely. Even though I never used an autopilot in a plane I owned, I'm looking forward to turning on the AP in the G3X package I'm putting in my RV9. With the quality of the technology now avaialbe it's really a no brainer if one plans to fly IFR today.

Steve (who's anxoius to get current in an Rv9)
 
You must log in or register to reply here.
Back
Top