Definition
A radio transmission that sends a steady, unbroken radio-frequency signal, typically switched on and off in patterns (such as Morse code) to carry information. In aviation, CW identification is still used by some ground-based navigation aids, most notably non-directional beacons (NDBs), which transmit their station identifier as a continuous-wave Morse signal.
Plain English
A radio signal that broadcasts continuously on one frequency, usually keyed on and off to spell out a station's identifier in Morse code.
Context Anchor
Seen in aviation abbreviation lists and in older radio communication or navigation discussions, especially where coded radio identifiers are mentioned.
Derivation
From the early days of radio: a 'continuous wave' was a smooth, steady signal, in contrast to the noisy 'spark-gap' signals that came before it. The name describes what it is — an uninterrupted wave on one frequency.
Why Pilots Care
Pilots tuning an NDB confirm they have the correct station by listening for its Morse identifier, which is sent as a continuous-wave signal. Without that check, you cannot be sure you are navigating off the right beacon.
Intuition Check
Do not read “continuous wave” as a physical wave of water or air. In this aviation radio context, it means a steady radio signal, often used with on-off code patterns.
Example Sentence 1
After tuning the NDB, the pilot listened for the CW Morse identifier to confirm the correct station before tracking inbound.
Example Sentence 2
The receiver picked up the steady CW tone before the code began.