Air Traffic Services (ATS)

Definition

Air Traffic Services (ATS) is a collective term encompassing all services provided to ensure the safe and efficient movement of aircraft through controlled and uncontrolled airspace. These services are typically managed by national air navigation service providers (e.g., Austro Control, DFS, NATS).

ATS plays a critical role in both VFR and IFR operations.

Main Objectives of ATS

Prevent collisions between aircraft and with obstacles.
Ensure safe and orderly traffic flow.
Provide information relevant to the conduct of flights.
Support search and rescue (SAR) efforts in emergencies.

ATS Subdivisions

Service	Description	Typical Phraseology Use
Air Traffic Control (ATC)	Ensures separation of aircraft in controlled airspace (IFR and sometimes VFR)	“Cleared to enter controlled airspace”
Flight Information Service (FIS)	Provides weather, traffic, and aerodrome info to pilots, especially in uncontrolled airspace	“Traffic information, aircraft westbound at 3500 ft”
Alerting Service	Initiates search and rescue if aircraft is overdue or in distress	Often silent; activated by ATC/FIS
Advisory Service	Available in advisory airspace where full ATC is not provided; offers collision avoidance advice	Rare in practice; mostly for procedural control areas

ATC Breakdown (Subtypes)

Unit	Function	Frequency Name
Ground (GND)	Issues taxi clearances	e.g., “Linz Ground”
Tower (TWR)	Handles takeoff/landing	e.g., “Wien Tower”
Approach (APP)	Manages arrivals and initial climbs	e.g., “Salzburg Approach”
Radar	Vectoring and sequencing using radar	e.g., “Linz Radar”
Delivery	Clearance delivery at large airports	e.g., “Wien Delivery”
Information (INFO)	Used at uncontrolled fields	e.g., “Vöslau Information”

Who Provides ATS?

In most countries, ATS is provided by a governmental or semi-private authority, such as:

Austria: Austro Control
Germany: DFS
UK: NATS
USA: FAA

These authorities maintain the infrastructure, staffing, and coordination of ATS across FIRs (Flight Information Regions).

Pilot Responsibilities

Even though ATS provides services, the pilot in command is always responsible for the safe operation of the flight, especially in uncontrolled airspace.

Maintain situational awareness
Respond clearly to ATC instructions
Request information if uncertain
Initiate emergency communication if needed