Time-based Separations

The Time-based Separations project will aim at defining and investigating the relevance of a new concept of operation applied to the arrival phase of flights. The actual distance based separations are to be replaced by time intervals, and/or speed compensation as applicable.

Description

The Time-based Separations project will investigate the possibilities of preventing loss of runway capacity under strong wind conditions while maintaining the required level of safety in:
  • Assessing a new concept of separation based on time intervals as opposed to current RADAR or ICAO Wake Vortex separation criteria defined as distances;
  • Investigating the use of longitudinal separations of less than 3 NM. (or less than 2.5 NM if this is in use); and
  • Exploring the possibilities of compensation of wind effect by aircraft speed adjustment and associated required ATC techniques.

Context

An important factor limiting today's airport capacity is the phenomenon of wake vortices generated by aircraft in flight. To avoid aircraft entering the zone of turbulence of another aircraft during the approach phase, minimum separation criteria between aircraft were published in the 1970's. These separations are expressed in terms of longitudinal distances and have since served to provide acceptable safe separations between aircraft at all major airports through the use of radar. However, under strong headwind conditions, the current distance separation thresholds have been seen to be too conservative as the ground speed of the aircraft decreases resulting in a lower runway capacity.

Objectives

The application of "Time-based separation" minima will not lead to any increase in runway capacity, but is expected to help prevent the loss of runway arrival capacity that typically occurs under strong headwind conditions. Note that as a first step, the Time-Based Separations project will only address operations dedicated to single runway arrivals, which are typical of most major European airports.

Approach

The Time-based Separations project will aim at defining and investigating relevance of a new concept of operation applied to the arrival phase of the flights.

Expected Results

The Time-based Separations project investigates the possibility to replace current distance separations between successive arriving aircraft by time intervals whilst maintaining the required level of safety. It would appear that if time separations were to be applied instead of distance separations then, in combination with suitable support systems and the use of appropriate working methods, most of the potential loss of runway capacity could be recovered.

For More Information

If you would like more information, contact:
Catalin Lepadatu
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Last validation: 14/09/2007