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Is an actual compass required?

FireMedic_2009

Well Known Member
Is an actual compass required if you have an EFIS and a G5 with battery backup? Along with ForeFlt on my phone and ipad a compass is not necessary but is it still legally required?

If it is required is it because the FAA hasn't gotten around to updating the regs?

Thanks!
 
In respect to using your EFIS compass, just a question for you all around the world - what is the recalibration period for your EFIS-based compass?

Here in NZ the Ye Olde Whiskey Compass has a recalibration period of 2 years whereas the recalibration of my GRT magnetometer is not even mentioned in the manual. When going through my C of A inspection (like getting your Pink Slip in USA) a couple of weeks ago I was told I had to add a two-yearly calibration check to my maintenance programme. What is the expectation in your country? Do you have to recalibrate the system on a calendar duration?
 
In respect to using your EFIS compass, just a question for you all around the world - what is the recalibration period for your EFIS-based compass?
Here in NZ the Ye Olde Whiskey Compass has a recalibration period of 2 years whereas the recalibration of my GRT magnetometer is not even mentioned in the manual. When going through my C of A inspection (like getting your Pink Slip in USA) a couple of weeks ago I was told I had to add a two-yearly calibration check to my maintenance programme. What is the expectation in your country? Do you have to recalibrate the system on a calendar duration?

No such requirement in U.S.
 
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Not required. In fact I just took my instrument checkride last month and had this discussion with the DPE.
 
Required versus needed

Probably not needed as well. With all of the cross checking the latest black boxes do, it would be a real shock if there wasn’t a GPS course-magnetometer cross check with count up/down timers or similar. The related code would be stone simple. Nothing sells LRUs like error messages

Would be nice if G3expert or other OEM could respond here regarding such cross checking. Though obvious, a response may not be in an OEM’s best interest.
 
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With all of the cross checking the latest black boxes do, it would be a real shock if there wasn’t a GPS course-magnetometer cross check

You are aware that magnetic heading and GPS ground track are not the same thing, right?
 
I always chime in with my experience on these threads; although it appears to OP is discussing ongoing flying vs the airworthiness inspection.

The FAA employee that inspected mine in 2010 required an actual compass in addition to my EFIS AHRS, even after I showed him EAAs info about it on my phone. He did agree it didn't have to be TSOd so luckily I was able to grab a cheapy from Walmart and I stuck it to the dash to finish the inspection.

Anyway, all that to say; even if you don't want one I'd have a cheap one on hand for your inspection in case your inspector wants to see one.
 
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I always chime in with my experience on these threads; although it appears to OP is discussing ongoing flying vs the airworthiness inspection.
The FAA employee that inspected mine in 2010 required an actual compass in addition to my EFIS AHRS, even after I showed him EAAs info about it on my phone. He did agree it didn't have to be TSOd so luckily I was able to grab a cheapy from Walmart and I stuck it to the dash to finish the inspection.
Anyway, all that to say; even if you don't want one I'd have a cheap one on hand for your inspection in case your inspector wants to see one.

The requirement (Not required for daytime VFR BTW) is for a "magnetic direction indicator". The regulation says nothing about it being independent.
The "compass" within the EFIS meets this requirement.

Having said that, the inspector may deny the Airworthiness application for anything he/she feels is "unsafe".
 
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I always chime in with my experience on these threads; although it appears to OP is discussing ongoing flying vs the airworthiness inspection.

The FAA employee that inspected mine in 2010 required an actual compass in addition to my EFIS AHRS, even after I showed him EAAs info about it on my phone. He did agree it didn't have to be TSOd so luckily I was able to grab a cheapy from Walmart and I stuck it to the dash to finish the inspection.

Anyway, all that to say; even if you don't want one I'd have a cheap one on hand for your inspection in case your inspector wants to see one.

Classic case of inspectors and examiners not understanding the rules/ enforcing their own. This is why I opened up a dialog with them first.
 
Isn’t a placard showing the magnetic deviation also required if you have a whiskey compass?
 
I always chime in with my experience on these threads; although it appears to OP is discussing ongoing flying vs the airworthiness inspection.

The FAA employee that inspected mine in 2010 required an actual compass in addition to my EFIS AHRS, even after I showed him EAAs info about it on my phone. He did agree it didn't have to be TSOd so luckily I was able to grab a cheapy from Walmart and I stuck it to the dash to finish the inspection.

Anyway, all that to say; even if you don't want one I'd have a cheap one on hand for your inspection in case your inspector wants to see one.

I ran into this too with a certain inspector out of the Washington DC FSDO who insisted on some type of whiskey compass. He knew an EFIS magnetometer met the reg requirement but he didn’t care. So we played the game, installed a “temp” compass complete with a deviation card and promptly removed it after the AWC inspection was complete.
 
You are aware that magnetic heading and GPS ground track are not the same thing, right?

Uh, yes. As mentioned, the code would be simple and memory (for any geo db reference) is cheap. Would it be 1/2 degree accurate? Probably not without utilizing more processor and memory resources. Could it be within a few degrees +/-? Easily with some rudimentary conditioning and filtering.
 
Uh, yes. As mentioned, the code would be simple and memory (for any geo db reference) is cheap. Would it be 1/2 degree accurate? Probably not without utilizing more processor and memory resources. Could it be within a few degrees +/-? Easily with some rudimentary conditioning and filtering.

Okay, well... based on experience I disagree, but the avionics manufacturers are hiring so good luck.
 
Probably not needed as well. With all of the cross checking the latest black boxes do, it would be a real shock if there wasn’t a GPS course-magnetometer cross check with count up/down timers or similar. The related code would be stone simple. Nothing sells LRUs like error messages

The difference between GPS track and magnetic heading is constantly changing, as it is based upon the atmo wind you are flying through and the boxes use that delta, along with airspeed, to determine wind direction / speed (derived not actual). So, there is no automated routine that can correct heading data using track info. The EFIS data relies upon accurate heading and track in order to calculate wind, therefore that wind data cannot be used to correct heading, as it was derived based upon the current magnetometer outpout - garbage in, garbage out. Just like making a tape measure by comparing to your height and then using it measure your height. It only tells you what you thought your height was, not what it actually is.

Larry
 
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@Larry, @Matt

I hear you and believe me I understand your points. I’m not thinking in terms of accuracy you’re probably used to. Simple example = the black boxes know the aircraft is on the ground. They know what runways and taxi ways it’s on. That labeling is generally +/- 9 degrees. All = the electronic equivalent of verifying runway heading and DI agree at takeoff. Your measuring stick example; if measured differently the next time you used it and you haven’t changed, time to recal or remake the stick.

I’m not thinking you could cal the magnetometer via flight data. Flag a relatively gross-ish discrepancy, why wouldn’t you? The avionics guys are way ahead of the government and probably a couple of decades ahead of released regs. I’m hoping one of them will chime in but am doubtful.
 
Isn’t a placard showing the magnetic deviation also required if you have a whiskey compass?

Yes, correct sir. And here in NZ this needs to be updated every two years.

I didn't fit a whiskey compass and the Inspector was happy with that but he wanted me to placard the corrections applied by the EFIS to the Magnetometer error. I explained how this was hardly relevant nor easily accomplished. He was also happy with that discussion but mandated that I add a bi-annual Compass Calibration to my maintenance programme. At the end of the day I added it so the maintenance programme could be approved however its hardly relevant. That said a calibration check every two years is not exactly a difficult task either when you have an automated system that only takes you 5 minutes to accomplish. But its the irregularities in rule interpretation that annoys me more than anything.

Thanks for your answers guys - and appologies for the slight thread course deviation.
 
Compass correction card.....

Isn’t a placard showing the magnetic deviation also required if you have a whiskey compass?

Oddly enough you have to have a compass correction card in the airplane if you have a whiskey compass but there is nothing saying it has to be filled out....:D
 
Oddly enough you have to have a compass correction card in the airplane if you have a whiskey compass but there is nothing saying it has to be filled out....:D
Funny you mention that. I had a whisky compass (didn’t want to argue over if it was needed) and a blank correction card. DAR, who was a good guy, says, ‘That has to be filled in. Now I know there’s no compass rose here, and you can’t fly without an A/W certificate, so I’m going to go and look at the wing tip, and maybe when I get back to the cockpit there’ll be a filled in correction card…’

Note for Mike: ‘biennial’= 2 years, biannual=6 months
 
After all these years of EFISes, are there *still* inspectors who don't understand this stuff and insist on "wet compasses" in addition to the perfectly acceptable ones that come with the EFIS?

Seriously?
 
Thank you Bob. I'll take that on board. :D

You learn summink new every day. I'm gonna bug heaps of people with that myself now.


Cheers,

Here in the US so many people misspelled ‘biennial’ that the FAA changed the name of the required two year review to ‘flight review’, dropping ‘biennial’, some years ago. But it’s still every two years!
 
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