Definition
An ATC instruction directing a pilot to turn off the automatic altitude reporting feature of the aircraft's transponder, while leaving the transponder itself operating. Used when the altitude information being received by ATC is invalid or unreliable.
Plain English
A controller's instruction telling you to switch off the part of your transponder that sends your altitude to ATC, but keep the rest of the transponder running.
Context Anchor
Heard on the radio when a controller believes the altitude being received from your aircraft is wrong or unreliable.
Derivation
Squawk' is ATC slang for transponder operation, dating back to the World War II 'Parrot' identification system. 'Stop altitude squawk' literally means 'stop transmitting your altitude through the transponder.'
Why Pilots Care
Prevents controllers from receiving incorrect or unwanted altitude information that could affect separation or vectoring decisions.
Intuition Check
“Stop Altitude Squawk” does not mean stop climbing or descending. It means stop sending automatic altitude information from the transponder.
Example Sentence 1
The controller said, 'November Two Three Alpha, stop altitude squawk, altitude differs by 400 feet,' and the pilot switched the transponder from ALT to ON.
Example Sentence 2
After the Mode C failed, the tower instructed the pilot to stop altitude squawk until the transponder could be checked on the ground.