Definition
An air traffic control instruction directing the pilot to switch off a specific transponder mode or to discontinue transmitting a particular assigned code. The pilot turns off the named function while leaving the rest of the transponder operating normally.
Plain English
ATC is telling you to turn off one part of what your transponder is sending — either a specific mode or a specific code — but not the whole transponder.
Context Anchor
Heard in radio communication with ATC when a controller needs an aircraft to change or stop a specific transponder output.
Derivation
‘Squawk’ comes from the World War II identification system code-named ‘Parrot,’ so transmitting an identification signal became known as squawking. ‘Stop squawk’ simply means stop transmitting that particular signal.
Why Pilots Care
Prevents the aircraft from broadcasting incorrect or unwanted identification and altitude data that could confuse controllers or trigger unnecessary alerts.
Intuition Check
“Squawk” does not mean a voice call or a noise here. It means the signal or number your transponder is sending, and “stop” applies only to the mode or code ATC named.
Example Sentence 1
After radar identification was no longer needed, the controller said, ‘Stop squawk Mode C,’ and the pilot switched the altitude reporting off while leaving the transponder on.
Example Sentence 2
Approach instructed the flight to stop squawk mode C once the aircraft descended below the Mode C veil.