Air data computer
Encyclopedia
An air data computer is an essential avionics
component found in modern glass cockpit
s. This computer, rather than individual instruments
, can determine the calibrated airspeed
, Mach number
, altitude
, and altitude trend from input data from sensors such as an aircraft
's pitot-static system
, gyroscope
s, GPS and accelerometer
s. In some very high speed aircraft such as the Space Shuttle
, equivalent airspeed
is calculated instead of calibrated airspeed.
Air data computers usually also have an input of total air temperature
. This enables computation of static air temperature and true airspeed
.
In Airbus aircraft the air data computer is combined with attitude, heading and navigation sources in a single unit known as the Air Data Inertial Reference Unit
(ADIRU). This has now been replaced by Global Navigation Air Data Inertial Reference System (GNADIRS).
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
component found in modern glass cockpit
Glass cockpit
A glass cockpit is an aircraft cockpit that features electronic instrument displays, typically large LCD screens, as opposed to the traditional style of analog dials and gauges...
s. This computer, rather than individual instruments
Flight instruments
Flight instruments are the instruments in the cockpit of an aircraft that provide the pilot with information about the flight situation of that aircraft, such as height, speed and altitude...
, can determine the calibrated airspeed
Calibrated airspeed
Calibrated airspeed is the speed shown by a conventional airspeed indicator after correction for instrument error and position error. Most civilian EFIS displays also show CAS...
, Mach number
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
, altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
, and altitude trend from input data from sensors such as an aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
's pitot-static system
Pitot-static system
A pitot-static system is a system of pressure-sensitive instruments that is most often used in aviation to determine an aircraft's airspeed, Mach number, altitude, and altitude trend. A pitot-static system generally consists of a pitot tube, a static port, and the pitot-static instruments...
, gyroscope
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
s, GPS and accelerometer
Accelerometer
An accelerometer is a device that measures proper acceleration, also called the four-acceleration. This is not necessarily the same as the coordinate acceleration , but is rather the type of acceleration associated with the phenomenon of weight experienced by a test mass that resides in the frame...
s. In some very high speed aircraft such as the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
, equivalent airspeed
Equivalent airspeed
Equivalent airspeed is the airspeed at sea level in the International Standard Atmosphere at which the dynamic pressure is the same as the dynamic pressure at the true airspeed and altitude at which the aircraft is flying. In low-speed flight, it is the speed which would be shown by an airspeed...
is calculated instead of calibrated airspeed.
Air data computers usually also have an input of total air temperature
Total air temperature
Total air temperature is a term used generally in aviation. In other applications it is called stagnation temperature. Total air temperature is measured by a specially designed temperature probe mounted on the surface of the aircraft. The probe is designed to bring the air to rest relative to the...
. This enables computation of static air temperature and true airspeed
True airspeed
True airspeed of an aircraft is the speed of the aircraft relative to the airmass in which it is flying. True airspeed is important information for accurate navigation of an aircraft.-Performance:...
.
In Airbus aircraft the air data computer is combined with attitude, heading and navigation sources in a single unit known as the Air Data Inertial Reference Unit
Air Data Inertial Reference Unit
An Air Data Inertial Reference Unit is a key component of the integrated Air Data Inertial Reference System , that supplies air data and inertial reference information to the pilots' Electronic Flight Instrument System displays as well as other systems on the aircraft such as the engines,...
(ADIRU). This has now been replaced by Global Navigation Air Data Inertial Reference System (GNADIRS).
See also
- Acronyms and abbreviations in avionicsAcronyms and abbreviations in avionics-A:*ACARS: Aircraft Communications Addressing and Reporting System.*ACAS: Airborne Collision Avoidance System.*ACP: Audio Control Panel.*ACS: Audio Control System.*ADAHRS: Air Data and Attitude Heading Reference System.*ADC: Air Data Computer....