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What is considered a peripheral device for the Digital Air Data Computer (DADC)?
  • A
    Radio altimeter.
  • B
    Vertical accelerometer.
  • C
    Angle of attack vane.
  • D
    Standby altitude and airspeed indicator.

What the examiner calls a peripheral device is simply a probe or any sensor. Initially, only the temperature and the pitot/static pressures were provided to the ADC. From these inputs, it was able to compute and provide airspeed (Pt-Ps = CAS/IAS), Mach number, altitude, TAS, and GS indications. However, now the AOA probe also provides inputs to the ADC. All this data is joined together and is transmitted from the ADC to other systems such as the FMS, AFCS, TAWS, TCAS, transponder, EFIS (via the symbol generator), etc.

The radio altitude is not measured by or transmitted to the ADC. The same stands for the vertical accelerometers that are part of the IRS. The standby altitude and airspeed measurements are totally part of the ADC, however, this data is the primary input to the ADC. As mentioned above, the AOA probe came at a later stage and has only been integrated into the ADC circuit to provide the angle of attack, hence being called a peripheral “device”.

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