Which statement about HF power and RADALT stability is correct?

Which statement about HF power and RADALT stability is correct?

• A. It may cause fluctuations in RADALT indications
• B. It has no effect on RADALT
• C. It stabilizes RADALT
• D. It only affects altitude hold mode

Answer: (A)

HF power fluctuations can affect the radar altimeter’s stability because the radar system needs a clean, stable electrical and RF environment to measure distance accurately. When the HF power supply or associated wiring introduces noise or voltage variations, that disturbance can couple into the radar’s transmitter or receiver circuits, altering signal strength or timing and causing the altitude readout to jitter. This is why you can see fluctuations in RADALT indications in the presence of unstable HF power. The other options assume no effect, a stabilizing effect, or a limitation to altitude hold mode, which isn’t the case—the RADALT can be influenced by HF power anytime the RF system or its power supply is noisy or unstable.

HF power fluctuations can affect the radar altimeter’s stability because the radar system needs a clean, stable electrical and RF environment to measure distance accurately. When the HF power supply or associated wiring introduces noise or voltage variations, that disturbance can couple into the radar’s transmitter or receiver circuits, altering signal strength or timing and causing the altitude readout to jitter. This is why you can see fluctuations in RADALT indications in the presence of unstable HF power. The other options assume no effect, a stabilizing effect, or a limitation to altitude hold mode, which isn’t the case—the RADALT can be influenced by HF power anytime the RF system or its power supply is noisy or unstable.