Proposed change to UK and Irish airspace transition altitude

To make more efficient use of the airspace over the UK and Ireland, and to align airspace more closely with other nations, the UK Civil Aviation Authority (CAA) and Irish Aviation Authority (IAA) have today notified the aviation industry of their intention to harmonise the Transition Altitude in both UK and Irish airspace.
The aim of the change is to significantly raise the Transition Altitude with the overall aim of achieving commonality with neighbouring States airspace through co-ordinated changes. 

The Transition Altitude is the height where aircraft change from operating their altimeter by reference to an altitude derived from a local pressure setting, expressed in feet (normally above mean sea level), to an area-wide standard pressure setting that allows the flight to be conducted using an internationally agreed set of Flight Levels.

At lower levels, it is important for a pilot to know the vertical distance from the ground in order to ensure safe separation from terrain and other obstacles.  This requires aircraft to use a local pressure setting to derive their altitude above mean sea level.  

The UK Transition Altitude is not currently consistent across the UK and varies between 3,000 ft and 6,000 ft depending on location and type of airspace. This was set in the 1950s when aircraft instrumentation and air traffic control systems were much less accurate and aircraft performance was lower. Modern commercial aircraft reach these sorts of altitudes extremely quickly on departure, and the change in operating techniques as the aircraft passes through the Transition Altitude adds to the complexity and workload for pilots at a critical stage of the flight.

Also, for pilots of most light General Aviation aircraft, there will be one less pressure setting to have to consider. This will assist in the drive to reduce airspace infringements as confusion over which setting to use, and therefore the indicated height of the aircraft, has led to aircraft infringing lower levels of controlled airspace. As such there is a safety benefit to be derived from the proposed changes both inside and outside controlled airspace.

A change to the Transition Altitude would also ultimately bring environmental, efficiency and capacity gains by simplifying the modernisation of the UKs airspace system as proposed by the Future Airspace Strategy.

NATS, the Ministry of Defence and Irish Air Corp have indicated their support for the change in principle, and the CAA and IAA have therefore announced the intention to launch a consultation on the revision to the Transition Altitude for the UK / Ireland Functional Airspace Block commencing this Spring.

Phil Roberts, Assistant Director of Airspace Policy at the UK CAA, said: There have been various proposals in the past to change the UK Transition Altitude that have not been followed through to completion. However, this time we have the impetus and very strong justification for the change as a key enabler for the Future Airspace Strategy and for the modernisation of UK airspace.  As a consequence, we are committed to seeing the process through to delivery.

Subject to the outcome of the consultation, the new Transition Altitude is expected to be implemented during the winter of 2013/14.
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