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

Common Misconceptions

  • FIS is not ATC: Pilots often believe “Information” provides clearances. It does not.
  • Alerting service is always running: Even if not heard, ATC monitors flights for overdue reports or distress triggers.






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