Definition
A simple drafting tool with two hinged legs — one ending in a metal point and the other holding a pencil — used to draw circles or arcs and to step off equal distances on a chart.
Plain English
A small two-legged tool that holds a pencil on one side and has a sharp point on the other, used to draw circles or measure equal distances on a chart.
Context Anchor
Seen in maintenance work involving aircraft magnets, especially when checking or identifying magnetic polarity.
Derivation
From Latin 'compassus,' meaning to step or pace out, because the tool is 'walked' across the page on its two legs to mark distances.
Why Pilots Care
Enables accurate transfer of chart scale distances into nautical miles for route planning and fuel calculations.
Intuition Check
Do not confuse a pencil compass with a drawing compass or the aircraft’s cockpit compass. In this context, it is a small maintenance tool used to check magnetic direction or polarity.
Example Sentence 1
She used a pencil compass to draw a 25-nautical-mile ring around the airport on her sectional chart.
Example Sentence 2
During preflight, she used the pencil compass to check the distance between two waypoints on the sectional.