Definition
An adjustment added to an indicated altitude to compensate for the altimeter error caused by air temperatures that are colder than standard. Because a pressure altimeter is calibrated to the standard atmosphere, colder-than-standard air makes the aircraft fly lower than the altimeter indicates; the temperature correction, taken from an ICAO cold temperature correction table, is added to the indicated altitude to obtain the true altitude above the reporting station.
Plain English
When the air outside is colder than normal, the altimeter reads higher than the airplane actually is. Temperature correction is the number of feet you add to the altimeter reading to find out how high you really are.
Context Anchor
Seen when using the ICAO Cold Temperature Error Table and when checking cold-weather instrument approach altitudes.
Derivation
Temperature comes from an older word meaning a measured condition of heat. Correction means making a value right. In this context, the correction is not a change to the weather; it is a change to the altitude value used by the pilot.
Why Pilots Care
Prevents descent below safe altitudes or terrain clearance during cold-weather IFR operations.
Analogy
It is like adding a safety allowance because your measuring tool is slightly misleading in the cold. The altitude number may look safe, but the correction helps make the real clearance safe too.
Grounding Statement
In very cold air, pressure layers are closer together, so an aircraft can be lower than its indicated altitude suggests.
Intuition Check
Temperature correction does not mean correcting the temperature reading. Here it means adjusting an altitude because temperature affects how accurate a pressure-based altitude is.
Example Sentence 1
Before flying the approach into the mountain airport at minus 30 degrees Celsius, the crew applied a temperature correction from the ICAO table to each segment altitude.
Example Sentence 2
The pilot consulted the cold temperature table and added the required correction to the decision altitude.