ATS objectives

ATS objectives

Air traffic services (ATS) exist for one overriding reason: to keep aircraft from colliding — with each other in the air, and with aircraft and obstacles on the ground. Everything else ATS does builds on that. The exam expects you to reproduce the five objectives of ICAO Annex 11 and to know how the services are subdivided — and to remember that even with ATC on frequency, collision avoidance in VMC remains your job.

The five objectives of ATS (ICAO Annex 11 §2.2)

ICAO Annex 11 §2.2 states that the objectives of the air traffic services shall be to:

• (a) Prevent collisions between aircraft — the primary safety objective.
• (b) Prevent collisions between aircraft on the manoeuvring area and obstructions on that area — preventing runway incursions and ground collisions.
• (c) Expedite and maintain an orderly flow of air traffic — efficiency: ATC does not just prevent conflicts, it also optimises sequencing, routings and levels.
• (d) Provide advice and information useful for the safe and efficient conduct of flights — proactive information such as FIS, ATIS, traffic information and weather.
• (e) Notify appropriate organisations regarding aircraft in need of search and rescue aid, and assist such organisations as required — the alerting function (see the SAR phases INCERFA / ALERFA / DETRESFA).

Hierarchy: safety (a, b) always takes precedence over efficiency (c) and information (d). When requirements conflict, ATC decides in favour of safety.

How ATS is subdivided (Annex 11 §2.3)

Air traffic services comprise four services:

The ATC service itself is delivered at three levels:

• Area Control Service (ACC) — controlled en-route flight,
• Approach Control Service (APP) — arrivals and departures within the TMA,
• Aerodrome Control Service (TWR) — traffic at and in the vicinity of the aerodrome (CTR).

The pilot's continuing responsibility — see and avoid

Even in controlled airspace, the pilot-in-command remains responsible for seeing and avoiding other traffic whenever visual conditions permit (ICAO Annex 2 §3.2 "Avoidance of collisions"; in the EU: SERA.3201/SERA.3205). SERA.3205 puts it plainly: an aircraft shall not be operated in such proximity to other aircraft as to create a collision hazard. ATC provides active separation to VFR flights only where the airspace class prescribes it — an ATC clearance never relieves you of your lookout.

Europe (EASA / EU)

Regulation (EU) 2017/373 (ATM/ANS Common Requirements), Annex IV (Part-ATS), carries the Annex 11 objectives into EU law and binds ATS providers to them. The Single European Sky framework and the Network Manager (EUROCONTROL) support and coordinate ATS provision across Europe.

Germany (national)

DFS Deutsche Flugsicherung GmbH provides civil ATS in Germany on the basis of §27c LuftVG. Germany has three FIRs (Bremen, Langen, Munich) for area control, with approach and tower control at the controlled airports. The upper airspace above FL245 in north-western Germany is controlled by MUAC Maastricht directly under EUROCONTROL.

Exam essentials

• ICAO Annex 11 §2.2 lists five ATS objectives: prevent collisions between aircraft; prevent collisions on the manoeuvring area; expedite and maintain an orderly traffic flow; provide advice and information; notify and assist SAR.
• Safety objectives always take precedence over efficiency and information.
• ATS comprises four services: ATC, flight information service, alerting service and air traffic advisory service.
• The ATC service is provided by ACC (area), APP (approach) and TWR (aerodrome).
• The PIC remains responsible for see-and-avoid in VMC even inside controlled airspace (ICAO Annex 2 §3.2, SERA.3205).
• In Germany, civil ATS is provided by the DFS; the three FIRs are Bremen, Langen and Munich.