Representatives of the Nordic and Baltic countries have carried out a feasibility study that recommends adopting a common regional transition altitude (TA) of either 10,000ft or 18,000ft instead of the disparate and much lower TAs that they use now.
The civil aviation authorities of Estonia, Finland, Norway and Sweden have worked with Eurocontrol to examine the feasibility of adopting a common regional TA, and perhaps extending it eventually across all of Europe.
Transition altitude is a published height above sea level at which pilots climbing to their cruising level change their barometric altimeter datum from the regional pressure setting to the common international standard setting of 1013.2hPa, so that all altimeters above that altitude give identical readings.
Above the TA, altimeter readings are communicated as common flight levels. During descent, pilots change the altimeter datum back to the regional pressure setting when passing through the transition level, the lowest flight level above the TA.
Transition altitudes are local, regional or national, and vary considerably between about 3,000ft and 18,000ft. The USA and Canada have a common TA of 18,000ft.
Eurocontrol has itself conducted a study looking at the issues that such a change would involve.
The main arguments for changing the system of national or regional TAs include the benefits of commonality, and the elimination of the need for pilots to adjust their altimeter pressure settings at low levels - notably during climb and descent, where workload is high and collision with terrain is a greater risk.
Having a low TA that affects most standard instrument departures and arrivals is also undesirable, the study notes. The report says that ICAO guidance, recommending TAs should be set as low as possible above 3,000ft, is based on the fact that aircraft performance was much more modest at the time.
The International Federation of Air Line Pilots' Associations and the UK Guild of Air Pilots and Air Navigators backs a TA of at least 10,000ft in Europe, which is also the altitude recommended by the Nordic feasiblity study, with 18,000ft as the alternative if 10,000ft is not judged acceptable.
Source: Air Transport Intelligence news
