Definition
A material that is not attracted by a magnet and that cannot itself be magnetized. Common examples in aircraft construction include aluminum, brass, copper, plastics, and austenitic stainless steels. Nonmagnetic materials are used in locations where the presence of a magnetic field would interfere with the operation of nearby instruments, particularly the magnetic compass.
Plain English
Stuff that magnets don't stick to and that can't be turned into a magnet. It's used near sensitive instruments so it doesn't pull the compass needle off course.
Context Anchor
You may see this term when working near a magnetic compass, installing avionics, or choosing tools and hardware for areas where magnetism could affect an instrument.
Derivation
From the Greek 'magnetis lithos,' meaning 'stone of Magnesia,' the region in ancient Greece where naturally magnetic rock was found. The prefix 'non-' (Latin, 'not') simply negates it. So 'nonmagnetic' literally means 'not behaving like that magnetic stone.'
Why Pilots Care
Prevents compass deviation that would produce heading errors and unsafe navigation.
Analogy
Like using aluminum or wood screws instead of steel ones near a compass so the needle stays true.
Intuition Check
Nonmagnetic does not mean nonmetallic. Some metals, such as aluminum or brass, are commonly treated as nonmagnetic in aircraft use, while iron and steel are usually magnetic.
Example Sentence 1
The screws used in the compass mounting bracket must be nonmagnetic to avoid causing compass deviation.
Example Sentence 2
Aircraft builders select nonmagnetic material for brackets surrounding the magnetic compass.