Definition
An airspace area of defined horizontal and vertical limits assigned to a specific air traffic controller (or controller team) within an Air Route Traffic Control Center or Approach Control facility. The controller working that sector provides separation, sequencing, and other ATC services to aircraft operating within its boundaries, then hands traffic off to the next sector as the aircraft moves along its route.
Plain English
A chunk of airspace that one controller is responsible for. As you fly across the country, you pass from one chunk to the next, and each handoff means a new controller and usually a new radio frequency.
Context Anchor
Pilots encounter this concept during radio handoffs, frequency changes, and discussions of air traffic controller workload.
Derivation
Sector comes from the Latin secare, meaning 'to cut.' A sector is literally a piece cut out of a larger whole — here, a slice of airspace cut out of a Center's or Approach Control's total area of responsibility.
Why Pilots Care
Aircraft are handed off between sectors as they fly; each sector controller has authority and workload limits within their area.
Analogy
Think of a large work area divided among several people. Each person is responsible for one section, and an aircraft is handed from one responsible person to the next as it moves through the sections.
Intuition Check
A control sector is not a physical wall or a general region on a map. It is an assigned area of airspace used to divide air traffic control responsibility.
Example Sentence 1
As the flight crossed into the next control sector, Center handed them off to a new frequency.
Example Sentence 2
During busy periods the supervisor split one control sector into two to reduce workload.