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Magnetic Compass Question

PhatRV

Well Known Member
I have a Dynon magnetometer installed as a part of the avionics package. Is the regular magnetic compass required in addition to the magnetometer for VFR?

If the answer is YES, does it have to be a "certified" compass or any compass that shows a magnetic heading will do?

Thanks
 
The short answer is no (at least in the US).

When I got my RV-10 signed off by the local FSDO a decade ago this was a hot debate - in other words left to the guy doing the inspection. The RV-8 inspection was done April 2020 with no whiskey compass, just SkyView ADHARS modules.

As I read the rules the requirement is magnetic heading, not how it is provided.

Carl
 
Its up to the inspector. A magnetic direction indicator is required. However, there is no official language that mandates that it be mechanical vs electronic sensor. This is no different than using an electronic altitude source displayed on your PFD. However, some inspectors seem to think that it is different and the rule requires a whiskey compass. If they balk, best to point out that magnetic direction can be found via EITHER a piece of iron in a compass OR an electronic sensor that reports direction and either fulfills the requirement for magnetic heading indication. Obviously this is different than GPS ground track, so be sure they know that a magnetometer is installed. Not all glass panels have magnetic heading indication. Both of my inspectors brought this up, but both accepted the electronic magnetometer.

I think the wording trips them up, as the FAR says a compass is required Maybe it has changed by now), but this is only the case because no other means of identifying magnetic heading was available decades ago when the FAR was worded. All other instruments were called indicators, so a bit clearer that electronic can be used.
 
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Its up to the inspector. A magnetic direction indicator is required. However, there is no official language that mandates that it be mechanical vs electronic sensor. This is no different than using an electronic altitude source displayed on your PFD. However, some inspectors seem to think that it is different and the rule requires a whiskey compass.

It is NOT up to the inspector. §91.205(b)(3) states that there is a requirement for a "magnetic direction indicator". It say nothing about a compass and hasn't for many many years. If an inspector says that a compass is required, ask him/her to show you the regulation.
 
It is NOT up to the inspector. §91.205(b)(3) states that there is a requirement for a "magnetic direction indicator". It say nothing about a compass and hasn't for many many years. If an inspector says that a compass is required, ask him/her to show you the regulation.

Well, you are technically correct, BUT, there are issues that get in the way at times, I had the same FSDO inspector that Carl mentions above and a compass was mandatory or no AWC. As Carl stated, he knew the 91.205 wording but didn’t care and arguing got you absolutely no where and no sign-off. It wasn’t right but it is what it is. So the easiest solution was to say yes sir, yes sir three bags full, mount a cheap temp compass (with a correction card) and then yank it the moment after receiving the pink slip.
 
Well, you are technically correct, BUT, there are issues that get in the way at times, I had the same FSDO inspector that Carl mentions above and a compass was mandatory or no AWC. As Carl stated, he knew the 91.205 wording but didn’t care and arguing got you absolutely no where and no sign-off. It wasn’t right but it is what it is. So the easiest solution was to say yes sir, yes sir three bags full, mount a cheap temp compass (with a correction card) and then yank it the moment after receiving the pink slip.

Amazing. There is absolutely *no reason* for this kind of **** to continue, year after year, with some of the inspectors willy-nilly making up their own rules.

After getting my AWC and then Repairman's Cert, I'd have most assuredly been on the phone with the FSDO manager. Is the guy who required some builder to paint his fuel caps red still out there doing that? Criminy...
 
Well, you are technically correct, BUT, there are issues that get in the way at times, I had the same FSDO inspector that Carl mentions above and a compass was mandatory or no AWC. As Carl stated, he knew the 91.205 wording but didn’t care and arguing got you absolutely no where and no sign-off. It wasn’t right but it is what it is. So the easiest solution was to say yes sir, yes sir three bags full, mount a cheap temp compass (with a correction card) and then yank it the moment after receiving the pink slip.

After getting my airworthiness I would make it a point to inform him it has been subsequently removed...what a jackwagon. These are the people that have kept the certified GA fleet in the dark ages with significant impediments to safety. They care only about the threats to their government pension.
 
It is NOT up to the inspector. §91.205(b)(3) states that there is a requirement for a "magnetic direction indicator". It say nothing about a compass and hasn't for many many years. If an inspector says that a compass is required, ask him/her to show you the regulation.

Is §91.205 applicable to planes with an experimental airworthiness certificate or just planes with a standard airworthiness certificate?
 
Is §91.205 applicable to planes with an experimental airworthiness certificate or just planes with a standard airworthiness certificate?

It is applicable to Experimental Amateur-Built Aircraft when flown at night and/or IFR by the Operating Limitations.
 
Looks like no magnetic direction indicator (compass or other) is required for DAY VFR flight.

"14 CFR § 91.205 - Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements."

"(8) After completion of phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with § 91.205, this aircraft is to be operated under VFR, day only."
 
Looks like no magnetic direction indicator (compass or other) is required for DAY VFR flight.

"14 CFR § 91.205 - Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements."

"(8) After completion of phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with § 91.205, this aircraft is to be operated under VFR, day only."

My previous post was incorrect. Deleted to keep the knowledge base correct.
 
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I have a Dynon magnetometer installed as a part of the avionics package. Is the regular magnetic compass required in addition to the magnetometer for VFR?

If the answer is YES, does it have to be a "certified" compass or any compass that shows a magnetic heading will do?

Thanks

Regardless of rules and interpretations and personal beliefs, IF you fly long enough for enough years eventually you will get caught on top of a cloud deck with no battery and no alternator. Perhaps even at night. In those moments it will be very useful to have a reliable magnetic direction indicator as you will almost always have a good idea what direction to fly to get to clear air before your fuel runs out.
 
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Regardless of rules and interpretations and personal beliefs, IF you fly long enough for enough years eventually you will get caught on top of a cloud deck with no battery and no alternator. Perhaps even at night. In those moments it will be very useful to have a reliable magnetic direction indicator as you will almost always have a good idea what direction to fly to get to clear air before your fuel runs out.

While I agree with the spirit of your statement, I disagree with the conclusion that the only correct CYA is a magnetic compass.

I'm electing not to have a vacuum system, so my standby is a G5 for AHRS data. That's all on a backup stand alone battery pack which will outlast my fuel, so in my particular case, I don't see the need for a compass. I think at this point that's a pretty common setup.

Note that I don't have anything against having a compass, it 's just that in my case unrelated system design factors made it unnecessary. Therefore I won't be installing a compass unless some random Fed decides it's in their version of the common good to force me to do so.
 
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While I agree with the spirit of your statement, I disagree with the conclusion that the only correct CYA is a magnetic compass.

I'm electing not to have a vacuum system, so my standby is a G5 for AHRS data. That's all on a backup stand alone battery pack which will outlast my fuel, so in my particular case, I don't see the need for a compass. I think at this point that's a pretty common setup.

Note that I don't have anything against having a compass, it 's just that in my case unrelated system design factors made it unnecessary. Therefore I won't be installing a compass unless some random Fed decides it's in their version of the common good to force me to do so.

Yes, I agree, unnecessary.
 
Regardless of rules and interpretations and personal beliefs, IF you fly long enough for enough years eventually you will get caught on top of a cloud deck with no battery and no alternator. Perhaps even at night. In those moments it will be very useful to have a reliable magnetic direction indicator as you will almost always have a good idea what direction to fly to get to clear air before your fuel runs out.

You forgot to throw in low on fuel, an oil leak, a bad mag check and a sick passenger.
 
Sorry in advance for the thread drift.
So, if for day VFR flight in an experimental 91.205 does not apply. There is no language in my operating limitations that require any instrumentation for day VFR flight. Would it be then be legal to fly my RV with no instruments (Day VFR)? Would a DAR issue an airworthiness certificate with a totally blank panel?
 
Sorry in advance for the thread drift.
So, if for day VFR flight in an experimental 91.205 does not apply. There is no language in my operating limitations that require any instrumentation for day VFR flight. Would it be then be legal to fly my RV with no instruments (Day VFR)? Would a DAR issue an airworthiness certificate with a totally blank panel?

Legally, yes - no instrumentation is required at all for Day VFR - totally blank panel. Can you get a DAR to approve that? Depends on your rationale and ability to persuade.

Paul
 
Sorry in advance for the thread drift.
So, if for day VFR flight in an experimental 91.205 does not apply. There is no language in my operating limitations that require any instrumentation for day VFR flight. Would it be then be legal to fly my RV with no instruments (Day VFR)? Would a DAR issue an airworthiness certificate with a totally blank panel?

Yes, you are correct, that no instruments are required for day VFR. Having said that, a DAR may deny certification for anything he/she considers unsafe.

Example: If you are building an "ultralight type" aircraft, a DAR would probably sign it off. On a "Lancair IV P", probably not.
 
Thread drift

There seems to be a number of threads recently that get off on a kick about extreme corner conditions or situations that are beyond reasonable or prudent. This is one of them. Who in their right mind is going to fly an RV ( any model) without having basic flight and engine instrumentation? Maybe its Covid fatigue but we need to keep the discussion focussed on the purpose and need for the function and ways to meet it with the required accuracy and availability. For example - having a glass display with a magnetometer is more accurate (maybe) but much less available than a whisky compass. So is it prudent to have a standby whisky compass as a backup for a single string instrumented VFR aircraft? That is a worthwhile discussion - considering whether you meet the regulations with a blank panel is not.

KT
 
You are operating under Part 91. You must comply with 91.205 which includes a magnetic direction indicator.

What you are referring to with (8) does not mean you don’t need a magnetic direction indicator during phase 1, nor does it mean you only have to install it if you plan to fly IFR.
That statement means
1) You are already limited to Day VFR per the Operating limitations, unless you complete phase 1 AND equip for night and/or instrument flight

The first part of your interpretation is incorrect.

91.205 applies specifically to "powered civil aircraft with standard category U.S. airworthiness certificates" which therefore excludes itself from aircraft with experimental certificates. The experimental operating limitations adds the 91.205 requirement back explicitly for "night and/or instrument flight" with the statement quoted above, but 91.205 still does not apply for Phase II daytime VFR operations.

Skylor
 
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Regardless of rules and interpretations and personal beliefs, IF you fly long enough for enough years eventually you will get caught on top of a cloud deck with no battery and no alternator. Perhaps even at night. In those moments it will be very useful to have a reliable magnetic direction indicator as you will almost always have a good idea what direction to fly to get to clear air before your fuel runs out.
I agree, but unfortunately when I upgraded my panel to glass and modern radios, I was never again able to get a mag compass to read reliably within acceptable error at all points no matter where I located it.
On the other hand an independently powered backup device is a good if not better fallback -- mine is a Garmin 496 always plugged in and staying charged, with the bonus that it provides far more info than a mag compass ever could. And just in case, a spare set of batteries in the map box.
 
I agree, but unfortunately when I upgraded my panel to glass and modern radios, I was never again able to get a mag compass to read reliably within acceptable error at all points no matter where I located it.
On the other hand an independently powered backup device is a good if not better fallback -- mine is a Garmin 496 always plugged in and staying charged, with the bonus that it provides far more info than a mag compass ever could. And just in case, a spare set of batteries in the map box.

Given that the 496 is quite long in the tooth, have you replaced the battery recently? Otherwise you might be in for a surprise when you expect to have battery backup and the battery dies quickly.

Skylor
 
Now that you mention it...

Otherwise you might be in for a surprise when you expect to have battery backup and the battery dies quickly.

Of course I have to mention my one somewhat-relevant experience in this regard: the one time I really, really, really needed my handheld radio, it proved unable to transmit despite having a "half" battery indication. If you pressed the transmit button it would promptly die. And I had no backup battery for my backup radio... Now I have a new radio and carry an extra battery pack. :)
 
Given that the 496 is quite long in the tooth, have you replaced the battery recently? Otherwise you might be in for a surprise when you expect to have battery backup and the battery dies quickly.
Skylor
Excellent point. From time to time I have unplugged to verify it will stay on for a reasonable length of time, but it's been a while. Something to add to the CI checklist!
 
Regardless of rules and interpretations and personal beliefs, IF you fly long enough for enough years eventually you will get caught on top of a cloud deck with no battery and no alternator. Perhaps even at night. In those moments it will be very useful to have a reliable magnetic direction indicator as you will almost always have a good idea what direction to fly to get to clear air before your fuel runs out.

Like the one in nearly everyones pocket?
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Interesting discussion from many of you.

For my panel, I have the main Dynon 10" EFIS + one backup EFIS. I also fly with Foreflight so if the alternator is dead and 30 min back up battery expires, I still have the Foreflight with the magenta line. I also have a Samsung Galaxy phone with FltPlan and that is another backup. I plan to fly daytime VFR so based on the information provided, I should be good to go. I avoid flying at night because I don't have an IFR ticket and I only fly at night in the very bright Los Angeles basin, even with the IFR equipped rental.
 
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