Latest research into wake vortices and their behaviour is likely to lead to approval for aircraft to be more closely spaced on approach and departure.
Experts at the Eurocontrol Experimental Centre (EEC) near Paris predict that new tools for air traffic controllers will be able to show on their radar displays the minimum safe in-trail separation for any pair of aircraft.
So far aircraft spacing has been based on unsophisticated models that do not take into account today’s greater knowledge of wake vortices when combined with certain weather conditions that dissipate their energy faster, says the EEC’s senior operations adviser Jean-Pierre Nicolaon.
At the end of an EEC-hosted wake vortex workshop last week, Eurocontrol said that the International Civil Aviation Organisation separation standards depend simply on the respective weight categories of the leading and following aircraft. But, adds the agency, “the workshop concluded that it is necessary to improve wake vortex separation standards so as to mitigate congestion, especially at airports, while maintaining the current level of safety”. Participants in the workshop included the US Federal Aviation Administration and NASA.
Nicolaon says the main reason for the optimism about safe reductions in aircraft separation is the greater knowledge of wake behaviour yielded by new wake monitoring technologies like lidar, plus computer modelling of vortex patterns and energy attenuation rates that is proving itself to be an accurate predictive tool. But more data-collection work needs to be done to draw the best advantage possible with safety, Nicolaon says, and much of this needs to be specific to the busy airports at which the efficiency gains are most needed.
ICAO separations are measured in distance for approach and by time for departure. There is potential for separation reduction in both cases, but the research has shown that time separation is a more reliable indicator of wake risk, so it may become the standard for approach also. The kind of result Nicolaon expects to see is guidance for approach and departure controllers on their displays showing the distance separation which, in the prevailing local meteorological conditions – and taking into account aircraft types – provides the minimum safe time separation between any pair of aircraft.
DAVID LEARMOUNT / LONDON
Source: Flight International
