Definition
A radar vector issued by ATC to a pilot whose heading indicator (directional gyro) has failed. Instead of being given specific headings to fly, the pilot is instructed to make standard-rate turns left or right on the controller's command, and to stop the turn when told. The controller observes the aircraft's track on radar and calls each turn and stop based on what is needed to guide the aircraft along the desired course.
Plain English
When your heading instrument is broken, the controller talks you through turns one at a time -- 'turn left,' 'stop turn,' 'turn right,' 'stop turn' -- watching you on radar instead of asking you to fly to a specific heading.
Context Anchor
You may hear this during instrument flying or radar service after a heading instrument failure, usually as radio instructions from air traffic control.
Derivation
No gyro' refers to the loss of the gyroscopic heading indicator. 'Vector' comes from the Latin vehere, 'to carry' -- in ATC usage it means a heading or track the controller carries the aircraft along. Together: a vector given without relying on the pilot's gyro instrument.
Why Pilots Care
It lets the flight continue safely to an approach or airport when the primary heading reference is lost, avoiding disorientation or missed approach.
Grounding Statement
The controller is not telling you what heading to fly; the controller is telling you when to turn and when to stop turning.
Intuition Check
“No gyro” does not mean no guidance. It means the pilot is not using a reliable gyro heading instrument, so the controller provides turn-by-turn guidance instead of heading assignments.
Example Sentence 1
After the heading indicator failed in cloud, the controller said, 'Cessna 23 Bravo, this will be a no gyro vector, turn left,' and the pilot rolled into a standard-rate turn until told to stop.
Example Sentence 2
During the no gyro vector the pilot started a standard-rate right turn and called stop turn when the controller directed.