In the context of aviation and aerospace, an Air Data Inertial Reference Unit (ADIRU) is a critical system that provides flight control and navigation data to an aircraft's flight control computer and other systems. It is a combination of two main components:

• Air Data Computer (ADC): This component measures air data parameters such as:
• Static air pressure (Ps)
• Dynamic air pressure (Pd)
• Total air temperature (TAT)
• Angle of attack (α)
• Mach number (M)
• Airspeed (V)

These parameters are used to calculate other important flight parameters, such as altitude, vertical speed, and air density.

• Inertial Reference Unit (IRU): This component uses a combination of accelerometers and gyroscopes to measure the aircraft's:
• Acceleration (in all three axes: x, y, z)
• Angular velocity (roll, pitch, yaw rates)
• Orientation (roll, pitch, yaw angles)

The IRU provides the aircraft's inertial navigation data, which is used to calculate its position, velocity, and attitude (orientation in space).

The ADIRU combines the air data and inertial reference unit functions into a single system, providing a comprehensive set of data that is used for:

• Flight control and stability augmentation
• Navigation and positioning
• Autopilot and flight director systems
• Warning and alert systems (e.g., stall warning, overspeed warning)
• Aircraft performance monitoring and recording

In modern aircraft, the ADIRU is typically a highly reliable and redundant system, with multiple units and backup systems to ensure continued safe operation in the event of a failure. The ADIRU is usually connected to other aircraft systems, such as the flight management computer, autopilot, and flight control computers, to provide a comprehensive and integrated navigation and control system.