Definition 1 of 2
Definition
The process of comparing an instrument's readings against a known reference standard and adjusting it so that its indications agree with that standard within a specified tolerance.
Plain English
Checking an instrument against something known to be correct, then adjusting it so it reads accurately.
Context Anchor
Pilots encounter calibration in maintenance records, aircraft instrument checks, compass checks, and discussions of whether a gauge or system reading is reliable.
Derivation
From Latin 'calibra,' related to measuring the bore (caliber) of a tube or barrel. The idea carried over to mean 'setting a measuring device to a known standard.' That history fits the aviation use: confirming an instrument's measurements match a trusted reference.
Why Pilots Care
Accurate instruments are essential for safe altitude, speed, and fuel decisions; uncalibrated instruments can lead to incorrect readings and poor pilot choices.
Analogy
Calibration is like checking a bathroom scale with a known weight. If the scale says the known weight is too heavy or too light, you either adjust the scale or remember how far off it is.
Intuition Check
Calibration does not mean simply making a display look reasonable. It means comparing the reading to a trusted reference and either correcting it or knowing the error.
Example Sentence 1
Before the aircraft could be returned to IFR service, the altimeter was sent to the shop for calibration against a certified pressure standard.
Example Sentence 2
During the annual inspection the mechanic checked the calibration of the fuel quantity gauges.