Quantcast

Compass requirements?

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Will Aldridge

Well-Known Member
Log Member
Joined
Oct 30, 2009
Messages
954
Location
Northern Utah
I was just trying to figure out what the compass requirements are now?

Certain aircraft are equipped with "magnetic course indicators" as opposed to magnetic compasses. In simple language the glass panel aircraft have a magnetometer to provide that data to the system. If your aircraft is equipped with gps does that count? What if its removable like a tablet?

I'm just looking at the compass that came with my plane and it weighs 10.5 ounces, maybe not much but I'm looking at everything to keep the weight down. I know i could buy a different compass that's half the weight but money is an issue.
 

Marc Zeitlin

Exalted Grand Poobah
Joined
Dec 11, 2015
Messages
698
Location
Tehachapi, CA
I was just trying to figure out what the compass requirements are now?
If a standard category TC'd aircraft, then you have to meet the requirements of 14 CFR Part 91.205(b), which require a magnetic direction indicator, which an EFIS magnetometer is, as is a standard compass.

If we're talking about an E-AB aircraft here, then see your Operating Limitations. Most of them do not require compliance with 91.205(b) for day VFR flight, but for Night or IFR, most require the equipment specified in 91.205(c) and 91.205(d).

So if you never fly Night/IFR, and if your OL's don't require compliance with 91.205(b), then no - you don't need any type of magnetic direction indicator.

If your aircraft is equipped with gps does that count? What if its removable like a tablet?
GPS is not a magnetic direction indicator. So no. You need the compass or magnetometer for the EFIS.

I'm just looking at the compass that came with my plane and it weighs 10.5 ounces, maybe not much but I'm looking at everything to keep the weight down. I know i could buy a different compass that's half the weight but money is an issue.
Fly day VFR only and have standard OL's and you don't need a magnetic direction indicator.
 

12notes

Well-Known Member
Lifetime Supporter
Log Member
Joined
Aug 27, 2014
Messages
1,089
Location
Louisville, KY
I looked this up, and noted an oddity in the rules. The regulations have specific guidelines for performance of the magnetic direction indicator for transport category aircraft, and normal category rotorcraft (27.1327) , but does not have any guidelines for the magnetic direction indicator for normal category airplanes. I even found an Advisory Circular about swinging a compass that references a non-existent regulation number (23.1327). Looks like that regulation, along with a whole bunch of other ones in part 23, was removed in 2017, and replaced with this:

14 CFR 23.2500
This section applies generally to installed equipment and systems unless a section of this part imposes requirements for a specific piece of equipment, system, or systems.

(a) The equipment and systems required for an airplane to operate safely in the kinds of operations for which certification is requested (Day VFR, Night VFR, IFR) must be designed and installed to -

(1) Meet the level of safety applicable to the certification and performance level of the airplane; and

(2) Perform their intended function throughout the operating and environmental limits for which the airplane is certificated.

Marc is correct in that 91.205 does specify a magnetic direction indicator for day VFR if flying a certified aircraft, and for all aircraft for night VFR.

Part 23 (including 23.2500 above) applies for normal category airplanes, not experimental. There doesn't seem to be a regulation for experimental category magnetic direction indicators. As long as you have one, I think even a compass out of a Cracker Jack box would be legal for VFR at night in an experimental.
 

Will Aldridge

Well-Known Member
Log Member
Joined
Oct 30, 2009
Messages
954
Location
Northern Utah
If a standard category TC'd aircraft, then you have to meet the requirements of 14 CFR Part 91.205(b), which require a magnetic direction indicator, which an EFIS magnetometer is, as is a standard compass.

If we're talking about an E-AB aircraft here, then see your Operating Limitations. Most of them do not require compliance with 91.205(b) for day VFR flight, but for Night or IFR, most require the equipment specified in 91.205(c) and 91.205(d).

So if you never fly Night/IFR, and if your OL's don't require compliance with 91.205(b), then no - you don't need any type of magnetic direction indicator.

GPS is not a magnetic direction indicator. So no. You need the compass or magnetometer for the EFIS.

Fly day VFR only and have standard OL's and you don't need a magnetic direction indicator.
It's a kitfox and experimental not SLSA. I'm completely rebuilding it. My plan is to only fly as a light sport pilot so it seems like I might be good to leave it out. I'll check the limitations. Thanks for the reply.
 

Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
5,602
Location
Marion, Ohio
One tree looks that same as every other from 3000 AGL. Are you sure you are going the right direction?

Why would you want to leave out the compass? They don't weigh much do they?
 

BJC

Well-Known Member
HBA Supporter
Joined
Oct 7, 2013
Messages
11,571
Location
97FL, Florida, USA
One tree looks that same as every other from 3000 AGL. Are you sure you are going the right direction?
Perhaps they do, for city boys.
Why would you want to leave out the compass? They don't weigh much do they?
I don’t want to have a compass in, or above, my instrument panel. (E-AB with AHRS)


BJC
 

gtae07

Well-Known Member
Joined
Dec 13, 2012
Messages
2,001
Location
Savannah, Georgia
One tree looks that same as every other from 3000 AGL. Are you sure you are going the right direction?

Why would you want to leave out the compass? They don't weigh much do they?
Plenty of reasons why someone wouldn't need/want a physical wet/mechanical compass. Many EFIS systems have magnetometers which provide that function (and thus meeting the requirement for night/IFR); others with very simple day VFR only aircraft might not need it for local flying and/or could use a handheld or tablet/phone-based GPS. I know when I'm just flying around locally (which seems like never these days :( ) I navigate by prominent landmarks and sometimes the Skyview moving map (if it's hazy out). I rarely look at compass headings.

I seem to remember some controversy from a while back about some DARs insisting on a wet compass even on full-glass aircraft, but assuming it ever was an issue, I'm pretty sure it isn't one any more.
 

cluttonfred

Well-Known Member
HBA Supporter
Joined
Feb 13, 2010
Messages
7,563
Location
World traveler
Personally, even with a nice EFIS, I like the idea of independent instruments for direction, speed, and maybe altitude. I have a watch that can do two of those, so that and a separate ASI or AOA/LRI could do the trick, though a little wet compass of some sort would be easier to use. Even a little hiker’s pin-on ball compass could be mounted in an inconspicuous place for the day you need it.
 

Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
5,602
Location
Marion, Ohio
..... for the day you need it.
I was actually thinking about the Gimli Glider. They were sure glad they had one.


My brother flew the Citation X for a while. All glass cockpit. But there was still an old fashioned magnetic compass in the ceiling on a swing-down arm. I know the Citation X is a far way from a small experimental, but EFIS/Smartphone/GPS have the reputation of quiting unexpectedly. When was the last time you heard of a magnetic compass fail?*

----------
*When I was a student pilot I had one lesson in a tired old Piper Cherokee. There were several violations that should have grounded the thing. One of these was that the kerosene had leaked out of the compass. You could smell it in the cockpit. A required instrument malfunctioning? I changed flight schools after that.
 

Will Aldridge

Well-Known Member
Log Member
Joined
Oct 30, 2009
Messages
954
Location
Northern Utah
Well my iPad/gps will be my primary navigation and if it fails I've got my phone which has its own magnetometer in it so I will have that as backup. In addition I do have an LRI that's going on top of the glareshield.

But in regards to weight I'm adding 30 lbs of engine weight to a plane that doesnt have a lot of weight to give up. So everything will be looked at. Fortunately I've already found at least 20 lbs to take out of the plane and with the compass gone thats also more than half a pound added to that list. I'm losing weight and the plane is losing weight. I fully intend to have a homesick angel.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
13,476
Location
Memphis, TN
I have been night when the IPad and the Garmin portable lost signals. Luckily it was just before a fuel stop so we were close to destination. Failed because of static electricity on the canopy. It had happened one other time. External antenna fixed the important one. I tend use it as a heading bug. Poor mans heads up display.
 

Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
5,602
Location
Marion, Ohio
When I build E-AB, I don’t put any instruments in... I need that panel space for my cup holders and cookie holders.
That reminds me. All cars now have cup holders, but do you know of any that have burger and fries holders? There have been times when I needed that.

Hmmmm. Think of a "grab and go" $100 hamburger flight!🤣
 

Daleandee

Well-Known Member
Joined
Sep 11, 2015
Messages
1,155
Location
SC
I have a small SIRS compass that was gifted to me from a fellow pilot. Admittedly I don't use it much as my iFly 740b keeps me aware of my direction. I also generally run my iPhone using the iBFD monochrome app that works like a small EFIS -


Many times just looking outside can tell you where you are if you can tell the trees apart. ;) So ... while my SIRS is seldom used it's there if needed:

1592005381202.png
 

BJC

Well-Known Member
HBA Supporter
Joined
Oct 7, 2013
Messages
11,571
Location
97FL, Florida, USA
Circa 1942 compass issued by the U. S. Navy to a merchant marine captain. Works great, but is a little on the heavy side.

F36B9DF2-DF3A-4464-B21F-508E02802E11.jpeg

BJC
 

TiPi

Well-Known Member
Log Member
Joined
Aug 25, 2019
Messages
314
Location
Mackay (AUS)
I keep a small hikers compass in my flight bag. Just in case I have to walk home one day.
 

Pops

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 1, 2013
Messages
8,310
Location
USA.
One the ground I always know the directions day or night.
In flying, I'll take a compass. Would hate to be over mountains at night and lose the electrical system including running the battery down.
 

N804RV

Well-Known Member
HBA Supporter
Joined
Jun 9, 2013
Messages
260
Location
Mount Vernon, WA
I think the whole point was that if you have a Magnetometer driving the heading indicator in an EFIS with adequate design redundancy, you don't need a wet compass. I'm all for that!

The 'ole "whiskey" compass makes a nice aviation keep-sake. I have one sitting in the bookcase, right next to my old Astro-Compass, they kinda look cool together, like a little piece of history.
 

Daleandee

Well-Known Member
Joined
Sep 11, 2015
Messages
1,155
Location
SC
The 'ole "whiskey" compass makes a nice aviation keep-sake. I have one sitting in the bookcase, right next to my old Astro-Compass, they kinda look cool together, like a little piece of history.
Speaking of old pieces of history on the bookcase - I have a Heathkit paddle keyer like this one:

1592022805531.png

I haven't used it in probably 20 years or more and would be very rusty with it now! As far as the compass is concerned, I'll keep it in the airplane along with a sectional.
 
Top