2.1  General

The pressure type altimeter, calibrated in accordance with the Standard Atmosphere.

1. when set to a QNH altimeter setting will indicate ALTITUDE;
2. when set to a QFE altimeter setting will indicate HEIGHT above QFE reference datum;
3. when set to a PRESSURE of 1013.2 hPA may be used to indicate FLIGHT LEVELS.

Altimeter settings provided to aircraft for approach, landing and take-off i.e. QNH, Aerodrome QFE and Runway Threshold QFE will be rounded down to the nearest whole hectopascal.

The reference datum for QFE is the aerodrome elevation except in the case specified here under.

The QFE supplied to aircraft for approach, landing and take-off in respect of instrument Runways (including Precision Approach Runways), where the landing threshold is seven feet or more below the aerodrome elevation, shall be the “RUNWAY THRESHOLD QFE”. The reference datum in this case will be the threshold elevation of the particular Runway.

QNH Area 1

This area is the area south of a line 5339N01100W 5339N00720W excluding Dublin CTA and regional Airports within the area. The QNH to be used in this area will be the Shannon aerodrome QNH

This will be transmitted as the Southern QNH H24

NOTE: This is also the QNH that will be issued for operations over sea areas

QNH area 2

This area is land areas north of 5339N01100W 5339N0720W excluding Dublin CTA and Regional Airports within this area.The QNH to be used in this area is the Sligo Airport QNH. This will be transmitted as the Northern QNH H24.

This area is the area contained within the Dublin CTA. The QNH to be used in this area will be the Dublin Aerodrome QNH. This will be transmitted as the Dublin QNH H24. NOTE: This is also the QNH that will be issued for operations over sea areas.

A transition altitude is specified for each aerodrome at which Air Traffic Control Service is provided.

Transition Altitudes at Aerodromes within the Shannon Flight Information Region are as follows: -

Examples of the relationship between flight levels and altimeter indications are given in the following table:

2.2  Take-off and Climb

2.3  Vertical Separation – En Route

Vertical Separation Minima are

1. FL290 to FL410-1000ft for RVSM approved aircraft.
2. Above FL450 2000ft

1. Up to FL450 – 2000ft
2. Above FL450 – 4000ft

2.4  Approach and Landing

This does not preclude a pilot using a QFE setting for terrain clearance purposes during the final approach to the runway but references to the vertical position of the aircraft in messages to or from the ground will be expressed in altitudes.

2.5  Missed Approach

The Altimeter settings used while completing a Missed Approach Procedure will be dependent upon whether or not the procedure can be carried out below the Transition Altitude. In any event the Altimeter settings used should be consistent with the relevant portions of Para 2 and 3.

3.1   Cruising Levels

IFR flights operated OUTSIDE Controlled Airspace should be flown at Flight Levels in accordance with the IFR section of the Table of Cruising Levels.

3.2   Terrain Clearance

It is the responsibility of the pilot to ensure that the Flight Level or Flight Levels selected provide adequate terrain clearance at all points along the routes to be flown. The latest and most appropriate QNH altimeter setting report should be used for assessing terrain clearance.

3.3   Procedures for VFR flights

Compliance with the procedures in Para’s 3.3.1 and 3.3.2 must not be interpreted as allowing any deviation from the Visual Flight Rules.

3.4   Flight Planning

1. in terms of Flight Level in the flight is to be conducted at or above the Transition Level, and
2. in terms of altitude if the flight is to be conducted at or below the transition altitude.

1. should ensure adequate terrain clearance at all points along the route to be flown
2. should satisfy air traffic control requirements, and
3. should be compatible with the table of Cruising levels.

The information required to determine the lowest flight level which will ensure adequate terrain clearance may be obtained from the appropriate services unit (e.g. Aeronautical Information, Air Traffic or Meteorological).