RVSM: new flight levels for European air routes

Between 1995 and 2001, the EUROCONTROL Experimental Centre (EEC) conducted six real-time simulations for the European Reduced Vertical Separation Minima (RVSM) programme. The aim of the project was to increase the capacity of European airspace by adding six new flight levels within 40 European countries.

In aviation, altitude is determined by measuring the difference between a reference pressure (atmospheric pressure at sea level) and the pressure where the aircraft is flying. Aircraft use air routes which are located at given altitudes, or flight levels (FLs), expressed in terms of hundreds of feet above the reference pressure line. A plane flying at FL 300 is thus 30,000 feet above the 1013.25 hPa line.

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How to reduce separation between aircraft

Before 2002, the conventional vertical separation minima (CVSM) between aircraft were 1,000 feet up to FL 290 and 2,000 feet above that level. In 1999 the EEC in Brétigny, in cooperation with nine European countries, conducted a series of real-time simulations (RTSs) to validate the concept of a reduction of the CVSM by means of the RVSM programme.

The participants looked into the possibility of using new flight levels and reversing the direction of use of the existing FLs 310, 350 and 390. In practical terms, these three levels, which were already used in an east-west flow, were reversed and operated from west to east. The allocation of certain altitudes to specific routes between several air traffic control centres was also investigated. Thus two particularly difficult real-time simulations needed to be conducted in order to study new systems for defining flight levels.

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A success story which has spread around the globe

These ambitious objectives gave rise to one of the biggest simulations every carried out at the EEC. “This RTS beat all records with 70 controllers involved for an unprecedented period of seven weeks. At the time no other simulation facility would have been able to provide a platform capable of carrying out this experiment,” said Roger Lane, Project Manager at the EEC.

The results obtained were decisive in securing the successful introduction of RVSM within European airspace on 24 January 2002. Roger Lane summarised the achievement: “The event even went beyond the frontiers of Europe, paving the way for the introduction of the programme in many regions of the world. The result was a reduction in en-route delays as well as fuel savings for the airlines.”