Operating the HF radio at high power may cause fluctuations in RADALT indications.

Operating the HF radio at high power may cause fluctuations in RADALT indications.

• A. True
• B. False
• C. Not Applicable
• D. Unknown

Answer: (A)

High-power HF transmissions can create RF interference that affects sensitive avionics, including the radar altimeter. The radar altimeter sends a microwave signal downward and relies on a clean receiver and signal path to measure altitude above terrain. When the HF transmitter is operating at high power, RF energy can couple into aircraft wiring, antennas, or the altimeter’s front-end, potentially saturating the receiver or generating spurious signals. This interference can cause the RADALT indication to jitter or fluctuate, especially during low-altitude work where precise altitude readings are critical. In practice, this means the statement is true: you can see fluctuations in RADALT when the HF radio is run at high power. It's a reminder to manage HF power during sensitive phases of flight and to be aware of RF interference as a factor affecting cockpit instruments.

High-power HF transmissions can create RF interference that affects sensitive avionics, including the radar altimeter. The radar altimeter sends a microwave signal downward and relies on a clean receiver and signal path to measure altitude above terrain. When the HF transmitter is operating at high power, RF energy can couple into aircraft wiring, antennas, or the altimeter’s front-end, potentially saturating the receiver or generating spurious signals. This interference can cause the RADALT indication to jitter or fluctuate, especially during low-altitude work where precise altitude readings are critical.

In practice, this means the statement is true: you can see fluctuations in RADALT when the HF radio is run at high power. It's a reminder to manage HF power during sensitive phases of flight and to be aware of RF interference as a factor affecting cockpit instruments.