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To Compass or not?

drone_pilot

Well Known Member
Hello All,

I am nearing the completion of an RV-7A with dual Dynon Skyviews. It seems like I had read somewhere that I would not be approved for night VFR unless I had a compass installed. Is this true? Regardless of whether there is a rule or not, what is the general consensus of adding a compass to a glass cockpit? As a follow up question, would a pedestal compass work okay with a Tip Up canopy?
 
Even if you choose to avoid the argument with your inspector of whether it is required for VFR (day or night) and decide you will just install one, you already meet the requirement.

FAR 91.205 lists the requirement for certificated aircraft as a Magnetic Heading Indicator (it does not say magnetic compass) Your Skyview system already has a Magnetic Heading Indicator.
 
I don't have a compass other than the ADAHRS for my Skyview. That should be all you need with a glass cockpit.
 
I love having a compass in my face. Such a great backup and super easy visual reference when position reporting your direction from wherever.

I have always mounted one on the windshield center bar sitting even with top of panel.

Plus its cheap.
 
If you will be flying IFR, a simple whiskey compass that is never wrong nor dependent on software and electrons has some major utility.
 
now, FAR 91.205 states what is required for ( standard category U.S. airworthiness certificates ) with the magnetic direction indicator, but do all theses rules under 91.205 still apply to our Experimental Special airworthiness certificate ?
 
now, FAR 91.205 states what is required for ( standard category U.S. airworthiness certificates ) with the magnetic direction indicator, but do all theses rules under 91.205 still apply to our Experimental Special airworthiness certificate ?

Your OPLIMS will provide guidance, but standard OPLIM wording says that for night or IFR lfight, 91.205 applies.
 
When flying our Mooney VFR, with steam gauges and yoke mounted GPS, on several occasions we had to revert to map and compass due to GPS failures, alternator failures etc. This normally happens at the most inopportune times.

In the RV we have Dynon Skyview, iPad, and a Garmin 500 in the back seat and have not had a failure in 250 hrs. In Canada it is a requirement to install a whisky compass as well.

I have flown enough to know that "stuff" happens and I find it comforting that if / when it does, I can revert to the compass and outdated maps my wife keeps her finger on...
 
In Canada the regulation requires a magnetic compass that operates independent of the aircraft electrical system. The Skyview is wired into the electrical system, so isn't independent, and as a result in Canada you'd need a compass.

When I first installed my Dynon D10A I didn't have a remote magnetometer, and the D10A had an internal backup battery. It would operate independently of the electrical system, so I removed my wet compass. Never got ramp checked to test whether das fed would agree with my interpretation, but I remain confident I would have made it through unscathed if the question came up.

I've since installed the remote magnetometer, which gives a much more accurate heading, and re-installed the wet compass as i'm no longer meeting the "independent" requirement.
 
Just to expand and complicate an interesting discussion, when the word independent is used, does that context refer to the aircraft electrical system? A question, is the IPad battery powered running Wing X, and ILevil battery powered AHRS qualify for independent magnetic direction indicator?
 
In Canada the regulation requires a magnetic compass that operates independent of the aircraft electrical system. The Skyview is wired into the electrical system, so isn't independent, and as a result in Canada you'd need a compass.

Not a requirement in the U.S.A., but some level of back up is not a bad idea. That is why since I have a single AFS 5600 screen in my airplane, I fly with my phone mounted on the panel in a temp mount with the Garmin Pilot app running on it. It provides a reliable back-up to a large majority of the capabilities of the EFIS.
 
now, FAR 91.205 states what is required for ( standard category U.S. airworthiness certificates ) with the magnetic direction indicator, but do all theses rules under 91.205 still apply to our Experimental Special airworthiness certificate ?

The answer is "no", because you don't have a "standard" airworthiness certificate (rules are very binary in that regard). However, there is at least one inspector at the Reno FSDO that does not understand the difference between the words "standard" and "special", despite them having different number of letters and different spellings....:rolleyes:

Ops Lims, of course, shoudl be consulted to see if they slipped in something requiring 91.205 equipment for your type of flying (night, IFR, etc.)
 
Just to expand and complicate an interesting discussion, when the word independent is used, does that context refer to the aircraft electrical system?
In Canada the regs specifically state *aircraft* electrical system. Or they did the last time I looked a number of years ago.

A question, is the IPad battery powered running Wing X, and ILevil battery powered AHRS qualify for independent magnetic direction indicator?
In Canada, in my opinion, yes, this would qualify. That opinion has not been tested via a ramp check however. I'm assuming the iPad and iLevil are connected via WiFi or Bluetooth, not hard-wired.
 
As I found out, what satisfies the requirement is of little consequence.

I'm in the camp that today's ADAHRS modules more than meet the letter of the law for magnetic reference. But - the Washington DC FSDO office made it clear they would not sign off on the plane without a TSO whiskey compass.

I chose not to fight the bear and installed this one: http://vansaircraft.com/cgi-bin/store.cgi?ident=1471963303-426-477&browse=fi&product=sirs-compass

The upside is it calibrates well and looks pretty. Every once in awhile I actually check to make sure it indicates the same as the SkyView.

So, find out what your inspector wants to see.

Carl
 
As I found out, what satisfies the requirement is of little consequence.

I'm in the camp that today's ADAHRS modules more than meet the letter of the law for magnetic reference. But - the Washington DC FSDO office made it clear they would not sign off on the plane without a TSO whiskey compass.

I chose not to fight the bear and installed this one: http://vansaircraft.com/cgi-bin/store.cgi?ident=1471963303-426-477&browse=fi&product=sirs-compass

The upside is it calibrates well and looks pretty. Every once in awhile I actually check to make sure it indicates the same as the SkyView.

So, find out what your inspector wants to see.

Carl

Ahh I know the specific inspector of whom you speak. Forewarned for my airworthiness inspection (and also unwilling to fight the battle), I bought a panel mount compass to replace my backup PFD just for the inspection. Fab'd up a filler bracket and everything. Never installed it though as it turned out I drew another inspector out of the FDSO who didn't care one iota about it.

However, he did get his in the end -- the unnamed inspector in question did my repairman's cert interview and it's wasn't a cake walk. ;)
 
I'm in the camp that today's ADAHRS modules more than meet the letter of the law for magnetic reference. But - the Washington DC FSDO office made it clear they would not sign off on the plane without a TSO whiskey compass.

This is the sort of BS that makes people hate government agencies...it's clear that if you have an ADAHRS, you don't have to have an antique wet compass. So how come employees of the Federal AVIATION Administration don't understand this? Are they not trained? Are they not getting directions or memos or annual training in the jobs they are supposed to do?

I know *I* don't get to make up nonsensical interpretations of the rules at MY job...
 
How much travelling do you plan to do?

Personally, I installed a vertical card mag compass when I already had an electronic device just because I don't want some fed, who either doesn't understand or is on a personal anti-glass crusade, selecting me for closer scrutiny. Do I use it? Never. Would I, even with an EFIS failure? Never. I have two, very reliable, very capable "portable" devices to help me navigate. Just do not like getting certified letters in the mail. And if I lose the GPS network and my EFIS device simultaneously, well then I guess the jig is up.
 
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As has already been said, compass not necessarily required if you have another type of magnetic heading indicator.

I just wanted to post my experience to bolster the points a few others have made that when the electronic version of magnetic heading indicator fails, it is nice to have that bouncy, floaty thing available to get you home. It has done so for me on a couple of occasions.
 
Shucks Fellas....

True story.

We need a back up compass, ASI and Alti if we use glass in the UK.

That is the only time I buy Falcon instruments btw :)

So - time goes by and we update our install to include a Garmin 695 just in front of the fuel selector on our 7. Great location, no glare, easy to see, remote antenna etc etc.

A while later, a buddy points to the compass and says - it's way out. Like 30? out. Mmmmmm, better check.

Why, oh why, do Garmin make their antennas magnetic ?

The compass is just looking at the Garmin antenna on the coaming now. Must be love :rolleyes:
 
This is the sort of BS that makes people hate government agencies...it's clear that if you have an ADAHRS, you don't have to have an antique wet compass. So how come employees of the Federal AVIATION Administration don't understand this? Are they not trained? Are they not getting directions or memos or annual training in the jobs they are supposed to do.

The problem isn't the employees. It's the regulations that aren't keeping pace with technology. We have amazing glass panel, radio, ads-b, etc. technology available to us in the Amateur-Built market that certified aircraft aren't allowed to use... Until the regulations change, which can take forever, that's the way it is. The rank-and-file who you actually deal with face-to-face are just doing their job enforcing the rules as they stand.
 
The problem isn't the employees. It's the regulations that aren't keeping pace with technology. We have amazing glass panel, radio, ads-b, etc. technology available to us in the Amateur-Built market that certified aircraft aren't allowed to use... Until the regulations change, which can take forever, that's the way it is. The rank-and-file who you actually deal with face-to-face are just doing their job enforcing the rules as they stand.

Maybe that is your perspective in Canada, but when the U.S. rules just say the requirement is that you have a "Magnetic Heading Indicator" but an inspector still requires an additional mag. compass with an EFIS, even though the EFIS derives its heading with a magnetometer sensing the same magnetic field of the earth that the mag. compass does, then that is a case of an inspector writing their own rules.
 
Good point, Scott, you are correct. Canada is just *slightly* more restrictive in the wording... Just enough to be annoying. :)
 
This really tweaks my hide, this is like saying we have to use a manual Frankenstein movie style blade contactor instead of an electric relay solenoid. It does the same thing, one Mag Direction Indicator needs 12 volts, the other does not, but it dose the same thing, one is floating and simple, the other is not, BUT, it does the same *&%#$@ thing! Just glad we don't need to burn a wick in oil for landing lights :cool:
 
This really tweaks my hide, this is like saying we have to use a manual Frankenstein movie style blade contactor instead of an electric relay solenoid. It does the same thing, one Mag Direction Indicator needs 12 volts, the other does not, but it dose the same thing, one is floating and simple, the other is not, BUT, it does the same *&%#$@ thing! Just glad we don't need to burn a wick in oil for landing lights :cool:

The good news, however, is that the Reno FSDO did sign off on our Tundra with no wet compass - just a three-screen Skyview system. So there is hope for them.
 
The good news, however, is that the Reno FSDO did sign off on our Tundra with no wet compass - just a three-screen Skyview system. So there is hope for them.

That's good to hear Paul, that's who I will be using hopefully by the end of this year, #2 on hanger wait list :rolleyes:
 
Maybe that is your perspective in Canada, but when the U.S. rules just say the requirement is that you have a "Magnetic Heading Indicator" but an inspector still requires an additional mag. compass with an EFIS, even though the EFIS derives its heading with a magnetometer sensing the same magnetic field of the earth that the mag. compass does, then that is a case of an inspector writing their own rules.

The rules as written in Canada do not require a wet compass, they require a magnetic heading indication device that can operate independently form the main electrical generating system.

Some idiot at TC offered an interpretation that because something is connected to said electrical system, it therefore cannot operate independently from it. Really you have to read the interpretation to believe it, makes NO Sense.

So we in Canada are stuck installing wet compasses, despite the clear intent of the rule otherwise.

This issue drives me so bonkers, I expect I will try to fight it when my time comes!

<end rant>

So yeah, you lucky Americans, no wet compass needed :)
 
JF - it ain't worth fighting over. I have previously pointed out that Transport Canada has approved several airliners which have electronic compasses, yet they can't see their way clear to doing likewise for GA aircraft. Nobody ever said that the folks we pay to interpret the regulations must produce a logical interpretation or an interpretation with which the majority of concerned parties must agree. In short, our bureaucrats have ultimate authority with zero accountability. There's precious little we can do to change that situation.

With this being the case, install a compass - it doesn't have to be an expensive TSO'd one - and ensure you have installed a compass correction card. You can go to Canadian Tire and pick up a boating compass if you wish (check with our local EAA chapter president who recently came through an MD-RA Final Inspection with just such a device installed). You can affix it with a suction cup if you wish, and oh darn, it might have fallen off after the final inspection was completed. It's just not a big enough deal to get our knickers in a knot over.

On the other hand, I am upgrading the compass in our Sportsman and will have a brand new Airpath unit available. I am one who happens to enjoy having a piece of stone-age technology in the airplane. Our "daily flyer" aircraft has a WWII-vintage compass installed - it still works just fine and I don't see any harm in having a link to the past flying along with me.
 
When my RV-6 was inspected in 1999, my panel with no clock dials was the first one my DAR had seen. Even though the Rocky Mtn uEncoder had a magnetometer, I installed a compass in case it became an issue:

41nzXJKNU5L._AC_UL115_.jpg


The only comment my wise DAR had was that I needed a correction card for it. Once he left the airport the compass was relegated to a desk drawer where it still resides today.
 
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Thanks everyone for all of the input! I think I will go without the classic compass. If the ADAHRS fails, I have Foreflight on two iPads with a bluetooth GPS antenna, may trade it for a Stratus eventually. Besides, I have a compass on my iPhone too! From what I read, the iPhone compass is not dependent on GPS.
 
The rules as written in Canada do not require a wet compass, they require a magnetic heading indication device that can operate independently form the main electrical generating system.

Some idiot at TC offered an interpretation that because something is connected to said electrical system, it therefore cannot operate independently from it. Really you have to read the interpretation to believe it, makes NO Sense.

So we in Canada are stuck installing wet compasses, despite the clear intent of the rule otherwise.

This issue drives me so bonkers, I expect I will try to fight it when my time comes!

Keep in mind that not only do you have to fight TC on this, you have to fight MD-RA as well. MD-RA has internal policies that prohibit inspectors from signing off an aircraft that does not have a wet compass. Not only that, they can't sign one off that doesn't have a 406MHZ ELT either, never mind that there are no regulations requiring a 406MHZ ELT in Canada.

When I imported my RV-6 from the US, it had a wet compass, but I removed it when I installed the Dynon D10A, that has it's own internal, battery backed, magnetic compass. You can *remove* the aircraft's electric generating system, and it'll still work. It came with a 121.5MHZ ELT too, but this was (just) before MD-RA changed their policy.
 
FWIW, I don't have a wet compass in my plane. I do have 5 GPS's (1 IFR, 2 VFR as part of the EFIS, 1 VFR on my tablet, & 1 VFR on my phone).

I'll take flying a partial panel approach with one of the VFR moving maps over a compass any day of the week. YMMV....
 
Keep in mind that not only do you have to fight TC on this, you have to fight MD-RA as well. MD-RA has internal policies that prohibit inspectors from signing off an aircraft that does not have a wet compass. Not only that, they can't sign one off that doesn't have a 406MHZ ELT either, never mind that there are no regulations requiring a 406MHZ ELT in Canada.

When I imported my RV-6 from the US, it had a wet compass, but I removed it when I installed the Dynon D10A, that has it's own internal, battery backed, magnetic compass. You can *remove* the aircraft's electric generating system, and it'll still work. It came with a 121.5MHZ ELT too, but this was (just) before MD-RA changed their policy.

Rob - once again, I'm going to sound like a cantankerous old phart here, so I'll ask in advance for your indulgence...

MD-RA does NOT and CANNOT require a 406MHz ELT be installed. They do require an ELT be installed, and it must meet TSO C91a or newer. It cannot be one of the original TSO C91 ELT's - these have been ineligible for new installations for quite a few years now. The principal differentor between the 91 and 91a units is that, with a rare exception, 91a units have cockpit-mounted remote control panels, whereas the 91 units do not have. It is important to understand that some of the original 91 models could be activated remotely by a simple cockpit-mounted switch - this does not constitute the remote control panel functionality that came along in TSO C91a.

Again, MD-RA does not enforce any requirements for 406MHz, or at least they should not. Every MD-RA inspector is an individual, and human, thus capable of incorrectly interpreting their marching orders from head office. If an MD-RA inspector says a 406MHz ELT is required, please ask that inspector to show you the basis of that requirement, in writing. That should stop the argument in its tracks.
 
As Marc points out, but more generally interpreted, MD-RA has no regulatory powers. They can only apply the rules as they exist. We had this discussion here a year or two ago regarding the requirements around the avionics checks and when/for whom they are required.

If they make you get your avionics "check" before first flight (even when nowhere controlled airspace) and a 406 ELT, they have over stepped their bounds and imposed on you regulations that do not exist.

At the same time, it is true that each inspector is technically an individual delegate ... so maybe one could interpret the compass rule correctly!?
 
If you will be flying IFR, a simple whiskey compass that is never wrong nor dependent on software and electrons has some major utility.

Somehow, flying IFR with a dead glass panel and just a compass would not be very much comfort for me. :)
 
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