Air Traffic Services
As a VFR pilot you constantly deal with air traffic services: a tower clearance at a controlled airport, flight information from an FIS frequency en route, or the alerting service quietly watching over your flight plan. This lesson sorts out which service does what, who provides it where, and what you do when the radio fails — all frequent exam themes.
The four air traffic services (ICAO Annex 11)
ICAO Annex 11 subdivides the air traffic services into four services:
| Service | Task |
|---|---|
| Air Traffic Control service (ATC) | Active control of traffic with clearances and separation |
| Flight Information Service (FIS) | Information without clearances (weather, airspace, traffic information) |
| Alerting service | Alerting SAR organisations for aircraft in distress |
| Air traffic advisory service | Advisory separation for participating IFR flights in Class F airspace (rarely used in Europe) |
At uncontrolled aerodromes a further, aerodrome-level service exists in practice: an aerodrome flight information / advisory service (AFIS / AAS) provides information and recommendations to traffic at the field — but it is not one of the Annex 11 main categories and it issues no clearances.
ATC — three units for three flight phases
The air traffic control service is provided by TWR (Aerodrome Control Service), APP (Approach Control Service) and ACC (Area Control Service):
| Unit | Name | Task |
|---|---|---|
| TWR (Tower) | Aerodrome Control Service | Traffic at and around the aerodrome, runways, traffic circuit |
| APP (Approach) | Approach Control Service | Arrivals and departures, TMA |
| ACC (Area Control) | Area Control Service | En-route traffic within the FIR |
FIS — your information service en route
A pilot can contact FIS (Flight Information Service) by radio at any time during flight. FIS:
- provides information on weather, airspace activity and other traffic,
- is available throughout the FIR (Flight Information Region) in which you are flying,
- issues no ATC clearances — only information and advice; decisions remain with the pilot.
Airspace reservations and restrictions
- A TRA (Temporary Reserved Airspace) is airspace temporarily reserved, e.g. for military exercises. It may be crossed when it is not active.
- A restricted area may be crossed only under the restrictions that apply to it — typically permission of the responsible unit and conditions depending on the activity. Check NOTAM and the AIP before flight.
Radio failure
- At an uncontrolled aerodrome: join the traffic pattern as usual, watch carefully for landing and departing traffic, and land while complying with the visual flight rules.
- Transponder: in case of radio failure, set code 7600 on your own initiative — no request or instruction is needed. ATC then sees the radio-communication-failure indication on the radar display.
Europe (EASA / EU)
In EU law, the flight information service is governed by SERA Section 9 (SERA.9001–SERA.9010, including ATIS) and the alerting service by SERA Section 10 (SERA.10001) of Regulation (EU) No 923/2012.
Germany (national)
In Germany there are three flight information regions (FIRs) in the lower airspace: Bremen, Langen and Munich. FIS is provided by the DFS on the published FIS frequencies (AIP Germany).
Exam essentials
- ICAO Annex 11 subdivides ATS into four services: ATC, flight information service, alerting service and air traffic advisory service.
- The ATC service is provided by TWR, APP and ACC for aerodrome, approach and en-route traffic respectively.
- FIS provides information only — never clearances — and is available to every flight within a FIR by radio.
- A TRA may be crossed when inactive; a restricted area only under the applicable restrictions.
- On radio failure at an uncontrolled aerodrome: join the pattern, look out for traffic, land under VFR.
- Squawk 7600 is set by the pilot on his own initiative in case of radio failure.
- Germany's three lower-airspace FIRs are Bremen, Langen and Munich.