Magnetic anomalies ?

[Carbon Canary]

Australia has some very large deposits of magnetite ore, close to the surface, predominantly in WA but also in Tasmania.
I haven’t heard anyone mention any impact on a compass, when flying below 10,000’, but does it ?

[facthunter]

I don't recall it being significant to the ordinary compass. Called declination (variation). Where its a certain value, it's called "Isogonal" lines.   Nev

[Carbon Canary]

on further research, it apparently does happen- particularly to inbuilt magnetometers that are routinely installed in EFIS.
 

https://www.aviationsafetymagazine.com/features/when-magnetometers-and-compasses-go-bad/

[spacesailor]

Interesting read !.

Were did all these mysterious anomalies come from so suddenly ! .

AND if only small , on a longish flight , wouldn't it cancel itself out after passing the anomaly. 

spacesailor

[Jabiru7252]

I think any interference to compass readings caused by flying near magnetite deposits would be small compared to the normal compass swing we experience from turbulence etc. Gee, trying to navigate using just the compass in a Jabiru on a hot day was a challenge. (I miss the directional gyro from my GA days). 

[Old Koreelah]

There is one very prominant anomaly you blokes should definitely steer clear of while flying: