Positioned high up works for me as well.
The point of correct compass position was underscored to me when my small
Smiths
Compass leaked fluid at high altitude and became stuck. Consequently giving
a wrong indication of direction.
Back in the hangar I removed the Smiths compass, thinking that I would fix
sometime.
Meantime I intended to use a large new Garmin Compass that I had. I lined
up the aircraft with known directions. Then exercised a compass swing check.
The deviation was consistently severe, but also varied in severity dependant
on direction. I concluded that nearby wiring was disturbing the Garmin Compass
unit.
A few days later went to Cooke & Son in Hull and they fixed my Smiths Compass.
Back home put the unit back in position. Perfect, no deviation.
So I guess my comment would be some compass units seem more sensitive to
interference
than others. The Smiths uses a special oil and dampers. The small size
of the Smiths unit was perhaps also a factor.
For those who do the UK biennial IRR check, the compass is one of the required
instruments, though weirdly a GPS isnt..
Bob
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