Definition
A system of representing letters and numbers as sequences of short signals (dots) and long signals (dashes), transmitted as audio tones. In aviation, Morse code is used to broadcast the identification letters of navigation aids such as VORs, NDBs, ILS components, and DME stations, allowing pilots to confirm they have tuned the correct facility.
Plain English
A way of sending letters using short and long beeps. Each navigation station on the ground sends out its own three-letter call sign in these beeps, and the pilot listens to make sure they're tuned to the right one.
Context Anchor
Seen on instrument approach charts and heard when checking radio navigation signals in the aircraft.
Derivation
Named after Samuel Morse, the American inventor who developed the code in the 1830s for use on the electric telegraph. It survived into aviation because it transmits clearly through static and weak signals where a voice broadcast would be unintelligible.
Why Pilots Care
Confirming the correct Morse code identifier ensures the pilot is receiving the intended navigation signal and not a different station on the same frequency.
Intuition Check
Morse code is not a spoken message or an air traffic control instruction. In this context, it is usually just an identifying pattern of tones for a navigation signal.
Example Sentence 1
After tuning the VOR, the pilot listened for the Morse code identifier to confirm the station was operating before tracking the radial.
Example Sentence 2
Each navaid on the approach plate shows its Morse code so the pilot can verify the signal by ear.