Which navigation aid is most likely to be affected by thunderstorm activity?

Which navigation aid is most likely to be affected by thunderstorm activity?

• A. VOR
• B. ADF
• C. GPS
• D. DME

Answer: (B)

The main idea is that thunderstorms create a lot of electrical noise, especially at the low radio frequencies used by NDBs. An Automatic Direction Finder relies on the bearing from a non-directional beacon that transmits in the low-to-mid frequency range. Lightning and storm-associated static raise the ambient noise level and can cause rapid, unpredictable fluctuations in the received signal, making the bearing information from an NDB unreliable. In contrast, VOR and DME operate at higher frequencies (VHF/UHF) and are more immune to this storm-time static; they’re designed to be robust in typical weather. GPS uses satellite signals and, while it can be affected by certain atmospheric disturbances, thunderstorms don’t degrade those signals as directly or as severely as the low-frequency NDB/ADF pair. So, the navigation aid most likely to be affected by thunderstorm activity is the ADF (NDB).

The main idea is that thunderstorms create a lot of electrical noise, especially at the low radio frequencies used by NDBs. An Automatic Direction Finder relies on the bearing from a non-directional beacon that transmits in the low-to-mid frequency range. Lightning and storm-associated static raise the ambient noise level and can cause rapid, unpredictable fluctuations in the received signal, making the bearing information from an NDB unreliable.

In contrast, VOR and DME operate at higher frequencies (VHF/UHF) and are more immune to this storm-time static; they’re designed to be robust in typical weather. GPS uses satellite signals and, while it can be affected by certain atmospheric disturbances, thunderstorms don’t degrade those signals as directly or as severely as the low-frequency NDB/ADF pair.

So, the navigation aid most likely to be affected by thunderstorm activity is the ADF (NDB).