Definition
A generic term covering the range of services provided by air traffic control authorities to aircraft in flight and on the ground, including flight information service, alerting service, air traffic advisory service, and air traffic control service (area, approach, and aerodrome control).
Plain English
An umbrella term for all the different services that air traffic controllers provide to pilots — things like giving information, alerting search and rescue, offering advice, and actively directing traffic.
Context Anchor
You may see ATS in the AIM glossary, air traffic control discussions, international flight information, and documents that describe what services are available to pilots.
Derivation
From 'air traffic' (aircraft moving through the airspace system) and 'service' (something provided to a user). The plural form 'Services' is also common; the singular 'Service' is used here as the umbrella category that contains the specific sub-services.
Why Pilots Care
These services directly affect separation from other traffic, access to weather and routing information, and the speed of emergency response.
Intuition Check
Do not read “service” as casual customer service. In this context, it means an official aviation function provided to aircraft for safety, order, information, or emergency support.
Example Sentence 1
The country's Air Traffic Service is responsible for separating IFR traffic and providing flight information to pilots on request.
Example Sentence 2
ATS includes the alerting service that begins when an aircraft fails to arrive on schedule.