Definition
An Air Data Computer is an electronic unit that receives raw inputs from the aircraft's pitot-static system and outside air temperature sensor, then calculates and outputs key flight parameters — including altitude, airspeed, vertical speed, Mach number, and true airspeed — to the cockpit displays and other aircraft systems. Modern transport and advanced general aviation aircraft typically carry two or more ADCs so that a failure in one unit does not deprive the crew of air data information.
Plain English
A small computer that takes pressure and temperature readings from outside the aircraft and turns them into the altitude, airspeed, and climb rate numbers you see on your instruments. Most modern aircraft have more than one, so if one breaks the others keep working.
Context Anchor
Seen in instrument flying, glass cockpit systems, flight display descriptions, and equipment discussions for aircraft that calculate airspeed and altitude electronically.
Derivation
From 'air data' (information about the air the aircraft is moving through — pressure, temperature, density) and 'computer' (a device that calculates). The name is literal: a computer that processes air data. Earlier aircraft did this mechanically inside each instrument; the ADC centralizes the work electronically and shares the results with everything that needs them.
Why Pilots Care
Supplies the accurate real-time numbers required for navigation, autopilot operation, and instrument approaches.
Intuition Check
An ADC is not a general-purpose computer like a laptop. It is a dedicated aircraft unit that turns air measurements into flight information.
Example Sentence 1
When ADC 1 failed in cruise, the crew transferred the captain's displays to ADC 2 and continued the flight normally.
Example Sentence 2
During climb the pilot cross-checks altitude and vertical speed generated by the ADCs.