Aircraft fly almost direct routes

Analysis of radar data shows that FABEC ANSPs have consistently provided almost optimal horizontal flight profiles to airspace users. In 2017, horizontal flight profiles were close to the optimum as actual trajectories converged at 96.77 percent (2016: 96.45 percent) of the great circle distance. This is an excellent value, which allows for only marginal improvements in the future. Controllers have been providing the shortest routings on average to airspace users since the start of the second reference period in 2014. And this has been achieved despite the strong growth in traffic and the often unexpected and volatile variations in volume. Flying remains the most direct mode of transport. The formal target was, however, missed by 0.09 percentage points.

Due to operational, technical and economic restrictions, airspace users regularly do not file the most efficient flight plans. In daily operations, this inefficiency can be eliminated by controllers providing direct routings – known as “tactical directs” – offered flexibly by controllers during the flight. These tactical directs are at first glance very beneficial for airspace users as their flight paths will be shorter. This means that they will save flight time and burn less fuel. As controllers frequently provide this service, savings add up to a huge amount – although the individual saving might be only a few kilometres in each case.

However, from a network perspective this additional service is proving to be counterproductive when traffic is growing, when demand is volatile or when control sectors are being overloaded. Practical experience shows that the predictability of traffic flows deteriorates as aircraft – expected to follow the direct routings in the flight plan –  fly through different sectors than those originally planned.