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Airspace and operations

Airspace is not background knowledge, it is an operating input: it decides whether a clearance is required, whether radio is mandatory, and which visibility and cloud minima apply.

The four questions airspace answers

1. Do I need an ATC clearance?
2. Must I carry radio and maintain a listening watch?
3. Which visual meteorological conditions (VMC) must I keep?
4. Which service do I get – control, traffic information or flight information?

Everything else follows from those.

The abbreviations that turn up everywhere

These nine abbreviations are enough to find your way through almost any text about airspace.

• VFR — Visual Flight Rules
  A set of rules, not a weather condition.
• IFR — Instrument Flight Rules
  Flight on clearances and published procedures.
• VMC — Visual Meteorological Conditions
  The conditions under which VFR flight is permitted.
• CVFR — Controlled VFR flight
  A VFR flight operated on an air traffic control clearance.
• ATC — Air Traffic Control (in general)
  Issues clearances; in Germany it separates VFR from IFR only in class C.
• ATS — Air Traffic Services
  The umbrella term for control, flight information and alerting services.
• FIS — Flight Information Service
  The service in class G airspace; no separation, no clearances.
• FIR — Flight Information Region
  The reference volume for SIGMET and for the flight information service.
• FL — Flight level
  A pressure surface referenced to 1013.2 hPa — not a height above the ground.

The pages in this section

• Airspace classes in Germany – the full table for C, D, E and G.
• Controlled and uncontrolled airspace – what the difference means in practice.
• CTR, TMA, RMZ and TMZ – the areas that have their own names and their own obligations.
• VFR and IFR compared – two sets of rules, not two kinds of weather.
• Flight levels, transition and the semicircular rule – when an altitude becomes a flight level.

Airspace is national
ICAO defines classes A to G, but no State is obliged to use all of them, and the way they are applied differs considerably. The figures on this page refer to Germany. For a flight abroad, the Aeronautical Information Publication of the State concerned applies — even where the class letters are the same.

Official sources

• DFS Deutsche Flugsicherung GmbH: Aeronautical Information Publication Germany – AIP VFR – Effective 20 AUG 2026. Open source (retrieved 2026-09-13)
• DFS Deutsche Flugsicherung GmbH: Aeronautical Information Publication Germany – AIP VFR, GEN 2-1 to GEN 2-7 "Abkürzungen / Abbreviations" (bilingual German/English) – Effective 20 AUG 2026. Open source (retrieved 2026-09-13)

Related reading

• Airspace classes
• VFR and IFR
• QNH and the altimeter

Status of this page
An editorial overview for training purposes. The binding references are the applicable regulations, the Aeronautical Information Publication (AIP), NOTAM, the approved aircraft documentation and the publications of the competent authorities. NorthTrack is not an authority, an examining body or a flight training organisation.
Page current as of: 2026-09-13