Definition
A short sequence of dots and dashes transmitted by a navigation aid (such as an NDB or VOR) that audibly identifies the station to the pilot. The pilot listens to this signal through the navigation receiver's audio output and matches it against the identifier shown on the chart to confirm the correct station is being received and is operating normally.
Plain English
It is the station's call sign, sent as beeps in dot-and-dash patterns. You listen to it through your headset to make sure you are tuned to the right navigation aid and that it is actually working.
Context Anchor
Encountered when tuning and identifying an NDB before using its signal for navigation.
Derivation
Named after Samuel Morse, who developed the dot-and-dash telegraph code in the 1830s and 40s. Aviation kept the system long after general telegraphy faded because the simple tones cut through static and remain readable even when a station is weak or distant.
Why Pilots Care
Confirms the correct navigation aid is tuned before relying on it for course guidance or an approach, preventing use of a false or unintended signal.
Intuition Check
Do not assume the Morse code identifier is the navigation information itself. It is the station’s audible name; it confirms which signal you are receiving.
Example Sentence 1
After tuning the NDB, the pilot listened for the Morse code identifier and confirmed it matched the three letters shown on the approach chart.
Example Sentence 2
Before starting the ILS approach, the crew verified the localizer Morse code identifier was correct.