Magnetic Compass Attributes & Errors

San Diego Flight Instructor Garry Wing, of Fly The Wing Flight Training, explains the unique properties of the airplane's magnetic compass in this 5-minute video. For details on the material presented in this video, read the article on my website: flythewing.com/308/Blog/Entrie...
To view other videos and articles, visit the website at www.FlyTheWing.com

[@RiechCruz]

I believe you are the FIRST PERSON to ever explain this to me, where it made sense! I was actually able to speak about what I learned from this video. Thanks!

[@josephdouglas5242]

Informative and straight to the point. Perfect for exam cramming.

[@photo_rohan]

me right now

[@brandonblair6868]

@@photo_rohan Preach

[@abbieamavi]

*I love how straight forward you are!! The chart/map design of paper mapping technique, how you talked about Magnetic Variation was cool too.* 🤙😊

[@damianwhite1467]

Thanks for posting this! Really helps students to visualize the issues associated with compass errors.

[@Mnrusty1]

Excellent video. Thank you for great flight training presentations. Your explanations and demonstrations are exceptional.

[@michaelwojcik6577]

Been a dozen years since I thought about this stuff, great video. To the point. Thanks!

[@markcurtiss4647]

Explained very well. Thank you.

[@PilotCristina]

Thanks Garry! Great video. 👍🏻

[@__ROSS___]

God bless, Gary. I get a sense he is a very good flying instructor.

[@adolfconradigharas439]

Thankyou so much brother, this is very helpful. May GOD bless you, keep safe.

[@swiftbird4846]

Marvellously explained sir, I thank you. What a fantastic aptronym as well.

[@soflymike]

Awesome Video! thanks

[@AviAeroAsis]

thank you sir. great video. to the point.

[@3-5-9]

So great. Thank you!

[@lordsiomai]

very clear explanation!

[@hunterfagan6272]

You have an amazing voice

[@MattEbert]

Where were you when I was studying for my Orienteering merit badge?

[@shem4753]

Great explanation:)

[@smiththomas1457]

Well explained...

[@MegaGuitarpicker]

Very good!

[@999jakes]

Very helpfull. Thanks

[@flytoday]

thanks Garry. Hey does my GPS derived compass have the same inaccuracies?

[@anderspriebe5710]

nope

[@TheStraiker]

Nice and easy !!!

[@jacknapier7775]

Thanks so much!

[@nhlakaniphosangweni6301]

Thank you sir.

[@greencresset6056]

how things have moved. when i was learning how to fly there was no KZbin, no cell phones. during my initial training I used a circular computer to determine what holding entry i had to make. these days u have it on an app while everything else u need to know you have them on the internet. there is flight radar, live atc and a ton more. sweet.

[@dboydboy1000]

That sure sounds like a lot of compensating/tweaking...but my question is, do planes regularly fly over the magnetic North Pole? Thank you

[@GarryWing]

Considering the (magnetic) North Pole is presently located in the Arctic Ocean hundred's of miles from land, I would guess not many airplane fly over it. This is mainly theory and understanding the difference between Magnetic & True courses & headings, which is required at all levels of pilot testing. While most people these days rarely look at a compass in flight, they are still req'd equipment on all airplanes, and ya gotta know how it works to get any pilot license.

[@gabriellepruiti6561]

Travis-2313 AMEN

[@GarryWing]

Good question; but no, GPS knows nothing about things on the ground (VOR's, waypoints, airports). Everything in its database is referenced to Long/Lat. GPS also uses MAGVAR to derive what the 'real-time' Variation is. This is why using GPS to navigate to a VOR never really puts you right over the physical VOR...

[@user-xw9wt5ui7v]

good

[@Majicalpepper]

This is what I’m confused about... there’s always a mention of UNOS. But, does this only apply when coming FROM north or south headings? Or does this also apply when going TO north or south headings? You mention UNOS only when coming from north or south headings but didn’t mention any correction for the errors. You mentioned correction for errors when TURNING TO north or south headings. Does the 30* correction apply no matter if you’re coming FROM or going TO north or south headings? The IFH chapter 7 page 22 is also very confusing on this topic.

[@GarryWing]

When using the compass for turns, you're generally only concerned about the heading you roll OUT on; correcting for the error so you end on the desired heading. We don't concern ourselves much about the inherent errors that are occurring DURING the turn. Most of this is easily understood when demonstrated in the air, in an airplane (not X-Plane, and certainly not from watching videos).

[@PilotAir]

This is true only in northern hemisphere, right ?

[@user-gs9on2hx8f]

PilotAir . opposite in the southern hem.

[@st3ntor]

yes. In new Zealand we have ONUS instead of UNOS, SAND instead of ANDS

[@DamnYouRabbit]

What exactly is this so-called weight that causes the ANDS and UNOS errors? The old 2008 PHAK uses the term "compensating weights" as a way to correct the card from magnetic dip so we can read it normally in level flight. The FAA than added to it's PHAK errata sheet that "no known compass manufacturers have compensating weights." The brand new 2016 PHAK that just came out 2 days ago and the 2012 IFH say the errors are attributed to a CG displacement between the pivot point and the card, again to compensate for dip. And you are saying the weight is from a magnet on the card itself? Seems like I cannot find a clear answer anywhere as to what actually causes this. I know Falcon jets install 2 different compasses depending on if their operation is going to be in the North or South hemisphere, so I'm guessing it has something to do with Dip. Flight training in the southern hemisphere uses the acronym SAND, for example, the complete opposite phenomena of ANDS. They also use ONUS instead of UNOS. Just google "CAA flight instructor guide compass use," -1st link. I wish someone would break one open and put the results on KZbin.

[@GarryWing]

First, I commend you on wanting to know _"How Things Work"_... However, your questions about the compass are waaay beyond the scope of what you need to know as a pilot, IMHO. You don't need to know about Falcon jets, or the Southern Hemisphere, or CAA, etc., unless you intend to fly there. You're making this a bit more complicated than it is. In the compass in my airplane (standard issue Cessna), the two magnets are long, round pins; similar to a nail without a head. You can see them in the picture at the end of this article I posted that explains much of what I discussed in the video: flythewing.com/308/Blog/Entries/2016/7/10_Magnetic_Compass_Errors.html Whether they are "counter-weights", "compensating weights" or merely the opposite ends of the magnets inside the compass, they have weight, they have an arm and they create a moment, right? That's what's going on when you accelerate/decelerate (East/West) and bank/turn (North/South). Hope that helps, and I haven't totally confused you any more than I'm confused...:)

[@DamnYouRabbit]

Garry Wing Thanks for responding! Yes, I definitely agree it is way beyond what you need to know as a pilot. It has just become a "need to know" bit of a curiosity. It seems a lot of people explain this in different ways-just try asking different CFIs. You're answer would make sense if that magnet/pin had one arm that was longer than the other. If the pivot point rests equally in between the magnet/pin, and the pin is the same weight on each side of the pivot point, then an acceleration or deceleration should do nothing. Right? That's what's bothering me.

[@GarryWing]

Remember, there's a *magnetic force* on the North end of that pin that's always trying to orient to the North pole. It's not exactly balanced on the pivot point.

[@cptdigits]

@@DamnYouRabbit One side of the needle points down because the magnetic north pole is located on the ground, not in the air. That causes the apparent imbalance. The needle itself should be perfectly balanced if you take it out of a magnetic field.

[@GZA036]

You're heading East. Magnetic force pulls down the South (left) tip of magnet, lifting up the North side, offsetting the CG to the right of the pivot point. Then you accelerate East, the heavier, lifted up North side is pulled towards you by inertia... Wa-lah "Accelerate North"

[@ahmadtheaviationlover1937]

Pilots are natural born teachers!!! Hahaha

[@Night__Rider__]

i know this might sound weird but what would it do during a barrel roll

[@GarryWing]

I imagine there would be tremendous "dip" errors during a barrel roll. If you're looking at the compass during a roll, you're not doing it right:)

[@Night__Rider__]

im actually a student in aeronautics and this is one if the instrument questions and i did wonder why i would need to know what happens when your in a 30 degree climb then preforming a barrel roll

[@GarryWing]

I can't imagine how that would be helpful to know. I'd rather that you know that if you do a barrel roll, you need a parachute (91.307(c)).

[@Night__Rider__]

im not planning to fly yet im only doing the engineering side for now but thanks

[@tyrellweare657]

Good video, but you should really stipulate which hemisphere you are referencing!

[@GarryWing]

lol. Northern hemi: this video / Southern hemi: _opposite_ of this video.

[@pn9358]

Only accurate for NORTHEN HEMISPHERES!