Challenge 2
The current standard for vertical separation between aircraft, Reduced Vertical Separation Minimum (RVSM), began its process towards network-wide implementation in the late 1990s, marking a significant milestone in air traffic management.
However, rising traffic volumes and the introduction of new aircraft types means that airspace capacity may soon reach its limits (again). Certain central sectors face heavy traffic demand, and the avoidance of climatic hotspots (see Challenge 3) will mean more traffic around them. On the other hand, every aircraft has its optimal cruise altitude where fuel consumption is minimised, and those altitudes are very close for modern turbojet aeroplanes. Therefore, some flight levels are saturated.
Current vertical separation minima are dictated by the collision risk that comes from errors in altitude measurements (ASE, altimetry system error) and the (auto-)pilot’s limited ability to keep the aircraft at the intended altitude (Flight Technical Error) adding up the wrong way. Green-GEAR investigates whether the higher accuracy of geometric altimetry as opposed to barometric altimetry could allow reducing the minimum vertical separation requirement from 1000 ft or 200 ft, respectively, to a uniform 500 ft. This is called the RVSM2 concept.
Apart from the collision risk, putting aircraft closer to each other increases the probability that one encounters the trailing wake vortices of another. The project reviews the risk associated with it and identifies particularly difficult situations that would need to be dealt with advanced means of separation.
Collision risk and wake turbulence risk analyses are the input for an initial safety study that analyses the crucial points and derives safety requirements through a functional hazard assessment (FHA).