Definition
A small chart or placard, usually mounted near an instrument or piece of equipment, that lists the corrections a pilot must apply to the instrument's indicated reading to obtain the actual value. Common examples include compass calibration cards (showing the heading to steer for each desired magnetic heading) and airspeed calibration cards (showing calibrated airspeed for each indicated airspeed).
Plain English
A small reference card placed near an instrument that tells the pilot how much to adjust the instrument's reading to get the true value, because no instrument is perfectly accurate.
Context Anchor
Seen near the magnetic compass in the cockpit, especially during preflight checks and heading references in flight.
Derivation
From the Latin 'calibrare,' meaning to determine the correct measurement of something. The card 'calibrates' the pilot's reading by showing the known errors of that specific instrument.
Why Pilots Care
Allows pilots to apply known corrections so navigation and flight instruments remain accurate despite minor installation or magnetic errors.
Intuition Check
A calibration card is not proof that the compass is perfect. It is a correction guide that tells the pilot how to use a compass that still has small known errors.
Example Sentence 1
Before departure, the pilot checked the compass calibration card and noted that to fly a magnetic heading of 090, she would need to steer 093.
Example Sentence 2
After maintenance, the mechanic updated the calibration card to reflect the new instrument alignment.