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Which options best describes the principle of operation of the air data computer?

Pressure and temperature inputs from...

  • A
    the pitot/static and temperature probes are converted into electrical or digital signals, compensated for temperature and compressibility, and transmitted to instrument displays.
  • B
    the pitot/static and temperature probes are compensated for temperature and compressibility, and transmitted to instrument displays through pipelines.
  • C
    electrical or digital sensors are converted into pressure signals, automatically compensated for compressibility, and transmitted to instrument displays.
  • D
    electrical or digital sensors are converted into pressure signals, automatically compensated for temperature, and transmitted to instrument displays.

AIR DATA COMPUTER (ADC)

An Air Data Computer (ADC) is used by aircrafts to acquire data from pitot and static pressure sensors, data buses and analog inputs and convert those raw inputs into electrical signals, obtaining key air data parameters such as altitude, airspeed, height deviation and temperature to ensure safe and accurate flight detail, on both rotary and fixed wing aircraft. Two types of ADC exist – analog and digital.

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 only temperature measured in an aircraft usually fitted with an ADC (commercial aircraft) is the TAT; there’s no OAT probe. The OAT is internally calculated by the ADC by taking into account the ram rise and the recovery factor.

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