Instrument Flight Rules (IFR): Minimum Levels, Equipment, and Vertical Separation

010-05-05Pablo Asensio Martínez2026-03-271 min

Instrument Flight Rules (IFR) allow operation without external visual references, relying on aircraft instruments.

Minimum Levels (ICAO Annex 2, 5.1.2)

Except for takeoff or landing, an IFR flight shall be flown at a level which is not below the minimum flight altitude established by the State. If not established:

  • Over high terrain or in mountainous areas: At least 600 m (2000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft.
  • Elsewhere (flat terrain): At least 300 m (1000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft.

Equipment

The aircraft shall be equipped with suitable instruments and navigation equipment appropriate to the route (minimum one VOR, one ADF -if necessary-, and one DME according to EASA, or as appropriate according to ICAO).

Vertical Separation

  • RVSM (Reduced Vertical Separation Minima): Between FL290 and FL410, vertical separation is 1000 ft.
  • Non-RVSM: Above FL290, standard separation is 2000 ft.

Due to the semicircular rule:

  • In Non-RVSM airspace, two aircraft flying in the same direction (same track, e.g., East) will be separated by 4000 ft (e.g., FL290, FL330, FL370).
  • In RVSM airspace, they will be separated by 2000 ft (e.g., FL290, FL310, FL330).

Termination of Flight Plan

A flight plan shall be closed by an arrival report to the appropriate ATS unit after landing. The report includes aircraft identification, departure aerodrome, destination, arrival aerodrome, and time of arrival.