Definition
An electronic unit that receives raw inputs from the aircraft's pitot-static system and outside air temperature probe, then calculates and outputs digital values for airspeed, altitude, vertical speed, Mach number, and air temperature to the flight instruments and other aircraft systems.
Plain English
A small computer on the aircraft that takes pressure and temperature readings from outside the airplane and turns them into the airspeed, altitude, and climb-rate numbers shown on the displays.
Context Anchor
Seen in aircraft with electronic flight displays, including discussions of the vertical speed indicator tape, airspeed tape, and altitude tape.
Derivation
Digital' means the values are processed and sent as numbers (rather than as mechanical pressure acting on a needle). 'Air data' refers to information about the air around the aircraft -- pressure, temperature, and how fast the air is moving past it. So a digital air data computer is the box that turns raw air measurements into clean numbers the displays can use.
Why Pilots Care
Delivers accurate, lag-free vertical speed and other air data to the primary flight display, supporting precise instrument flight without the limitations of purely mechanical instruments.
Analogy
It is like a translator: it takes raw pressure and temperature information the pilot cannot use directly and turns it into flight information the pilot can read and act on.
Intuition Check
Do not think of the digital air data computer as the display itself. The display shows the results; the digital air data computer is the unit that calculates those results.
Example Sentence 1
When the pitot tube iced over, the digital air data computer began outputting unreliable airspeed, and the pilot switched to the standby instruments.
Example Sentence 2
During straight-and-level flight the pilot cross-checks altitude and airspeed values generated by the digital air data computer.