2.1   Take-off and Climb

A QNH altimeter setting is made available to aircraft in taxi clearance prior to take-off.

Vertical positioning of aircraft during climb is expressed in terms of altitude until reaching the transition altitude above which vertical positioning is expressed in terms of flight level.

2.2   Approach and Landing

2.3   En-route

The cruising level at which a flight or a portion of a flight is to be conducted shall be expressed in terms of flight level when operated above the transition altitude.

When flying in a controlled airspace associated with an aerodrome (TMA or CTR) at or below the transition altitude, the aerodrome QNH value given by the relevant control unit shall be used for the altimeter setting.

When flying outside controlled airspace at or below 4 500 FT AMSL, the altimeter shall be set to the regional QNH given on pilot's request by Brussels FIC, Steenokkerzeel ATCC or by any ATC unit. The regional QNH is the lowest of the QNH values for the following stations: EBAW, EBBE, EBBR, EBCI, EBCV, EBFS, EBBL, EBFN, EBLG, ELLX, EBOS, EBSH and EBSP.

VFR flights conducted at or below 3 000 FT AGL do not have to maintain a semi-circular cruising level and consequently are not compelled to use any particular altimeter setting. However, they are advised:

• to take into consideration, for terrain and obstacle clearance purpose, either the regional QNH or the QNH value relevant to the area overflown (EBBR, ELLX, EBOS and EBSP) obtainable from Brussels FIC or Steenokkerzeel ATCC;
• to take note that high speed low level military flights, having a flight visibility less than 5 KM, are mandatory conducted under IFR and are therefore maintaining semi-circular IFR cruising altitudes based on the regional QNH.