ENR 1.3  Instrument Flight Rules


Note: Unless explicitly indicated, the rules in this section apply in both Belgium and Luxembourg.

1.1   Rules Applicable to All IFR Flights (SERA.5015)
1.1.1   Aircraft Equipment

Aircraft shall be equipped with suitable instruments and with navigation equipment appropriate to the route to be flown in accordance with the applicable air operations legislation.

1.1.2   Minimum Levels

Except when necessary for take-off or landing, or except when authorized by the CAA, an IFR flight shall be flown at a level that is at least 1 000 FT above the highest obstacle located within 8 KM of the estimated position of the aircraft.

1.1.3   Change from IFR Flight to VFR Flight

An aircraft electing to change the conduct of its flight from compliance with IFR to compliance with VFR shall notify the appropriate ATS unit specifically that the IFR flight is cancelled and communicate thereto the changes to be made to its current flight plan.

When an aircraft operating under IFR is flown in or encounters VMC it shall not cancel its IFR flight unless it is anticipated, and intended, that the flight will be continued for a reasonable period of time in uninterrupted VMC.

Change from IFR flight to VFR flight shall only be acceptable when a message initiated by the pilot in command containing the specific expression ‘CANCELLING MY IFR FLIGHT’, together with the changes, if any, to be made to the current flight plan, is received by an ATS unit. No invitation to change from IFR flight to VFR flight shall be made by ATS either directly or by inference.

1.2   Rules Applicable to IFR Flights within Controlled Airspace (SERA.5020)

An IFR flight operating in cruising flight in controlled airspace shall be flown at a cruising level, or, if authorised by the ATS unit to employ cruise climb techniques, between two levels or above a level, selected from the table of cruising levels in ENR 1.7, § 3, except that the correlation of levels to track prescribed therein shall not apply whenever otherwise indicated in ATC clearances or specified in the AIP.

1.3   Rules Applicable to IFR flights outside Controlled Airspace (SERA.5025)
1.3.1   Cruising Levels

An IFR flight operating in level cruising flight outside of controlled airspace shall be flown at a cruising level appropriate to its track as specified in the table of cruising levels in ENR 1.7, § 3.

1.3.2   Communications

An IFR flight operating outside controlled airspace shall maintain an air-ground voice communication watch on the appropriate communication channel and establish two-way communication with the air traffic services unit providing flight information service.

1.3.3   Position Reports

An IFR flight operating outside controlled airspace shall report position, as specified in ENR 1.1, § 1.10.3.

1.4   Supplementary Rules
1.4.1   Flights Within Brussels UTA   General

Except as specified in § and in ENR 3.5, § 1 aircraft shall follow the RNAV routes published in ENR 3.3. Alternate ATS routes may be used on prior request made by the pilot to Brussels ACC or Maastricht UAC, if co-ordination of the different types of traffic allows it.

Cruising levels below FL 220 are normally not available for overflying traffic.   Free Route Airspace

Free Route Airspace (FRA) is a specified airspace within which users may freely plan direct routes between a defined FRA Horizontal Entry point (E) or FRA Departure Connecting point (D) and a defined FRA Horizontal Exit point (X) or FRA Arrival Connecting point (A), with the possibility to file via FRA Intermediate points (I), without reference to the ATS route network, subject to airspace availability and using the flight level orientation scheme concerned. Within this airspace, flights remain subject to ATC.

MUAC FRA procedures are available in the Brussels UTA between FL 245 and FL 660. Eligible flights are those over-flights that enter and exit MUAC FRA between FL 245 and FL 660. Additional eligible flights are those that depart from or arrive at aerodromes below the lateral limits of MUAC FRA or in its proximity and have a requested flight level above FL 245 within the FRA. Route points can be selected as defined in ENR 4.1 and ENR 4.4.

MUAC FRA is available H24. The ATS route network and Route Availability Document (RAD) Appendix 4 Direct Routings (DCTs) are removed above FL 245, except those segments required for the vertical connection to the lower airspace or for special purposes.   Reduced Reporting Procedures

Pilots shall apply the following procedures in order to reduce air-ground communications, unless otherwise instructed by ATC:

  • the initial call after a frequency change shall only contain aircraft identification and actual level, with the addition of cleared level for climbing or descending aircraft;
  • any position report, if required subsequently, shall only contain aircraft identification, position and time;
  • level changes shall only be reported on leaving assigned levels;
  • pilots shall, in the absence of prior instructions from ATC to change frequency, indicate that the aircraft is going to leave Brussels UIR by reporting: “approaching the UIR boundary” unless crossing the Brussels/Hannover UIR boundary;
  • aircraft that are not capable of replying on SSR with 4096 codes on Mode A, nor with automatic pressure-altitude transmission on Mode C, but that have been exceptionally authorized to operate in the Brussels UIR, shall make an abbreviated position report over all “on request” reporting points.   Formation Flights

Formation flights along ATS routes are authorized, provided that:

  • prior permission has been obtained in accordance with ENR 1.1, § 1.15.3;
  • a proper ICAO flight plan has been filed;
  • they are performed in accordance with ENR 1.1, § 1.5.8;
  • the formation leader squawks the assigned transponder code.

A formation flight will be handled by ATC as a single aircraft with increased radar separation (1 NM). When individual control is requested, advisory information will be issued to assist pilots in attaining standard ATC separation. When pilot-reports indicate that standard ATC separation has been established, normal ATC clearances will be issued.

Note 1: Separation responsibility between the aircraft within the formation during the formation flight and during transition to individual flight rests with the pilots concerned, until standard separation has been obtained.

Note 2: Formation join-up and break-away shall only be conducted when authorization has been obtained from ATC.

1.4.2   Flights Above FL 660

The lowest usable flight level above FL 660 is FL 670.

Flights above FL 660 should be conducted along the axes of the upper RNAV routes. Aircraft shall join or cross the axes of such routes at one of the reporting points listed in ENR 4.4. The flight plan shall only mention reporting points defining the upper RNAV routes.

Flights bound for Brussels UTA shall request entry clearance 5 MIN before the estimated time of entry, unless such clearance has been previously issued by an adjacent control unit.


2.1   Minimum safety height

The minimum safety height and the low flying regulation are laid down in ENR 1.1, § 2.7.

2.2   Flight Level

IFR flights shall select a level appropriate to its track as specified in the ENR 1.1, § 2.7, except for:

  • security flights;
  • flights under radar control;
  • when otherwise instructed by the appropriate ATS unit.
2.3   Change from IFR Flight to VFR Flight

A pilot encountering VMC during an IFR flight shall continue his flight according to IFR until receiving permission from the appropriate ATS unit to proceed in VFR.