Definition
A circular diagram, marked in degrees from 0° to 359° around its circumference, used to display magnetic directions. In the context of compass deviation, it is a painted or marked circle on the airport surface — aligned with magnetic north — onto which an aircraft is taxied so the compass can be checked and adjusted (swung) against known magnetic headings.
Plain English
A circle marked with all the compass directions in degrees. On an airport, it is a painted circle on the ground, lined up accurately with magnetic north, used to check whether the aircraft's compass reads correctly when the aircraft is pointed in different directions.
Context Anchor
Seen during a compass deviation check, often on a marked ramp area where the aircraft can be turned to specific headings.
Derivation
The term 'rose' comes from the old mariner's compass, where the points of direction were drawn as the petals of a flower or rose. The pattern stuck, and any circular diagram of compass directions is still called a compass rose today.
Why Pilots Care
Accurate deviation correction performed on the magnetic compass rose ensures the cockpit compass will indicate reliable magnetic headings once airborne.
Analogy
Think of it like a giant clock face for direction, except it is marked from 0 to 360 degrees and lined up with magnetic north.
Intuition Check
A magnetic compass rose is not the cockpit compass itself. It is the outside reference used to check what the cockpit compass is showing.
Example Sentence 1
Before the test flight, the mechanic taxied the aircraft onto the magnetic compass rose to swing the compass and update the correction card.
Example Sentence 2
After completing the swing on the magnetic compass rose, the pilot recorded the deviation values for each cardinal heading in the aircraft log.