Definition
The band of radio frequencies from 3 kHz to 30 kHz. VLF signals travel very long distances, follow the curvature of the Earth, and can penetrate seawater to shallow depths. In aviation, VLF was historically used for long-range navigation systems such as Omega before being superseded by GPS.
Plain English
A range of very slow radio waves that can travel huge distances around the world. Older long-range navigation systems used these signals to help aircraft find their position over oceans.
Context Anchor
Seen in aviation references that group radio signals by frequency range, especially in older or long-range navigation and communication discussions.
Derivation
Frequency comes from the idea of how often something repeats. In radio, it means how many wave cycles pass each second. Very Low Frequency describes radio waves at the low end of the radio-frequency scale.
Why Pilots Care
Certain legacy navigation systems and specialized communication equipment rely on VLF because its signals remain usable over very long distances where higher frequencies would fade.
Intuition Check
VLF does not mean the signal is weak or quiet. It means the radio waves are in a specific low-frequency range: 3 to 30 kilohertz.
Example Sentence 1
Before GPS became standard, transoceanic flights relied on VLF-based navigation systems to determine position far from land.
Example Sentence 2
VLF signals were used by early navigation systems because they could be received far beyond the horizon.