Airborne Weather RadarRadio Navigation — DGCA CPL practice questions
Question 1 of 11
A frequency used by airborne weather radar is:
All 11 questions — Airborne Weather Radar
Radio Navigation · DGCA CPL. The correct option is marked on each.
Q1. A frequency used by airborne weather radar is:
- A.8800 MHz
- B.9.375 GHz✓
- C.93.75 GHz
- D.1213 MHz
Why: AWR frequency = 9375 MHz = 9.375 GHz (SHF band). This gives the best returns from large water droplets (~3 cm) associated with severe turbulence.
Q2. AWR required to detect targets up to 200 NM. Maximum PRR:
- A.405 pps✓
- B.810 pps
- C.1500 pps
- D.750 pps
Why: Max PRF = 81,000 / 200 = 405 pps .
Q3. Weather beam preferred over fan-shaped beam for mapping in excess of ___ NM:
- A.20–25
- B.60–70✓
- C.100–150
- D.150–200
Why: Fan-shaped (cosecant²) beam used up to 60–70 NM . Beyond that, use pencil (weather/MAN) beam.
Q4. AWR is an example of ___ radar at frequency ___ in the ___ band:
- A.primary, 8800 MHz, SHF
- B.secondary, 9.375 MHz, UHF
- C.secondary, 9375 MHz, SHF
- D.primary, 9375 MHz, SHF✓
Why: AWR is primary radar at 9375 MHz in the SHF band.
Q5. Correct colour sequence as returns get stronger:
- A.red, yellow, green
- B.yellow, green, red
- C.green, yellow, red✓
- D.red, green, yellow
Why: Colour sequence in order of increasing return strength: Black → Green → Yellow → Red → Magenta .
Q6. A false indication of water may be given by AWR when:
- A.flying over land with Land/Sea switch in Sea position
- B.flying over mountainous terrain✓
- C.cloud/precipitation between aircraft and cloud target
- D.using mapping beam beyond 50 NM
Why: Hill shadows created by mountainous terrain can give a false impression of water (lakes) on the AWR display.
Q7. AWR operates at 9375 MHz because:
- A.8800 MHz gives best returns from all precipitation
- B.13300 MHz used
- C.9375 MHz gives best returns from rainfall associated with Cb✓
- D.9.375 GHz best for detecting aircraft
Why: 9375 MHz gives the best returns from large water droplets and wet hail found in convective clouds (Cb) associated with severe turbulence.
Q8. Mapping mode of AWR utilizes:
- A.pencil beam from 70 NM to 150 NM✓
- B.cosecant² beam effective to 150 NM
- C.pencil beam max range 70 NM
- D.cosecant² beam effective 50 NM to 70 NM
Why: MAP (cosecant²) is used up to 60–70 NM. For mapping beyond 70 NM, select MAN to use the pencil/weather beam from 70 NM to 150 NM .
Q9. AWR uses 9 GHz because the wavelength gives reflections only from:
- A.short wavelength produces higher frequency returns
- B.reflects from cloud water droplets of all sizes
- C.wavelength gives reflections only from the larger water droplets✓
- D.frequency penetrates clouds for good mapping
Why: 3.2 cm wavelength is comparable to the size of large water droplets and wet hail (~3 cm). This gives reflections from dangerous precipitation while ignoring smaller harmless droplets.
Q10. AWR antenna is stabilised:
- A.in pitch, roll and yaw
- B.in pitch and roll✓
- C.in pitch and roll whether stab on or off
- D.in pitch and roll only at 0° tilt
Why: AWR antenna is stabilised in pitch and roll . STAB OFF locks scanner to aircraft axes — display becomes lopsided during manoeuvres.
Q11. AWR colours: very light/no returns ___, light ___, medium ___, strong ___:
- A.black, yellow, green, magenta
- B.black, green, yellow, magenta
- C.grey, green, yellow, red
- D.black, green, yellow, red✓
Why: Colour sequence: Black (very light) → Green (light) → Yellow (medium) → Red (strong) → Magenta (turbulence).