Air Data ComputerNavigation — Instrumentation — DGCA CPL practice questions

All 6 questions — Air Data Computer

Navigation — Instrumentation · DGCA CPL. The correct option is marked on each.

1. Q1. Which of the following correctly lists the standard outputs of an Air Data System?

   • A.TAS, SAT, TAT, fuel flow
   • B.Altitude, vertical speed, airspeed (CAS), Mach number✓
   • C.Altitude, heading, airspeed, Mach number
   • D.Altitude, vertical speed, TAS, Mach number

   Why: The standard ADS instrument outputs are altitude, vertical speed, airspeed, and Mach number. TAS, TAT, and SAT are additional (optional) outputs. Heading is not an ADS output — it comes from gyroscopes or magnetic sensors. See Section 1 . — Standard = altitude, VSI, CAS/IAS, MNo. Additional = TAS, TAT, SAT. These categories are tested directly.

2. Q2. The purpose of the Configuration Module in an Air Data System is to:

   • A.allow the ADC to be manually programmed in case of sensor failure
   • B.calibrate the ADC for differences in probe positioning specific to each aircraft type✓
   • C.convert analogue signals to digital format for transmission
   • D.provide redundancy when the primary ADC fails

   Why: Because many aircraft types use the same basic ADC, the Configuration Module adapts it by accounting for the pressure/temperature gathering efficiencies of that specific aircraft's probe positions, obtaining the most accurate indications possible. See Section 1 . — The Configuration Module is an aircraft-specific calibration layer — it makes a generic ADC specific to one aircraft type's installation geometry.

3. Q3. In a digital Air Data Computer, the Analogue-to-Digital Converters process inputs from:

   • A.pitot pressure and static pressure only
   • B.pitot pressure, static pressure and total air temperature
   • C.pitot pressure, static pressure, temperature, and angle of attack✓
   • D.pitot pressure, static pressure and computed airspeed

   Why: The source text states that A-D Converters process "measurements of pressure, temperature and AOA". This includes pitot pressure, static pressure, TAT, and angle of attack (AOA). See Section 3.2 . — Inputs to ADC: pitot, static, TAT (and AOA in some types). Outputs include altitude, CAS, Mach, TAS, VSI, TAT, SAT.

4. Q4. Which type of BITE check runs automatically approximately once every second during normal ADC operation?

   • A.Power Up BITE
   • B.Maintenance BITE
   • C.Continuous BITE✓
   • D.Periodic BITE

   Why: Continuous BITE is an automatic check of all input and output stages carried out throughout ADC operation, approximately once every second. See Section 6 . — Three BITE types: Power Up (start-up), Continuous (every second, automatic), Maintenance (ground, manual). Know which is which.

5. Q5. A major advantage of an Air Data System over conventional mechanical instruments is that:

   • A.static pressure errors are eliminated because the static vents are heated
   • B.position error correction can be applied within the computer and shared across height and airspeed channels✓
   • C.the system does not require pitot or static sources
   • D.the system is immune to total electrical failure

   Why: Within the ADC, Position Error Correction (PEC) computed in the Mach number channel can be applied directly to the height and airspeed channels as well — a significant advantage over mechanical instruments where each instrument must compensate independently. See Section 7.3 . — The ADS advantage of centralized PEC is important — one computation corrects multiple outputs simultaneously. This is not possible with individual mechanical instruments.

6. Q6. Cross-coupled static vents located on each side of the fuselage are used in a pitot-static system primarily to:

   • A.provide backup static pressure in case one vent is blocked
   • B.reduce error caused by sideslip or yaw✓
   • C.increase the sensitivity of the static pressure measurement
   • D.prevent icing of the static vents

   Why: By averaging the static pressure from both sides of the fuselage, cross-coupled vents cancel out the pressure asymmetry caused by sideslip or yaw, producing a more accurate static reference. See Section 2 . — Cross-coupling = sideslip/yaw error reduction. Alternate static = backup for blockage. These are two different features — don't confuse them.