Time-Based Separation

The Time-Based Separation (TBS) project has developed new methods for separating arriving aircraft by time instead of applying distance separations in strong headwind conditions.


When there are strong headwinds, aircraft ground speed is reduced on final approach. This results in a reduced landing rate, causing delays and even flight cancellations. 

TBS aims at reducing the gap in landing rates in light and strong headwind conditions. It will help maintain airport capacity at the same level in all wind conditions.

The concept of time separation take advantage of wake vortex quick dispersion in strong headwinds: this fact makes it possible to reduce the distance between landing aircraft. Consequently, airports are able to operate with the same landing and capacity rates as in light wind conditions.

As the wake strength impacting on aircraft is lower when there are heavy winds, safety levels will be maintained even if the distance between the pair of aircraft is minor.

Other additional parameters (e.g. the aircraft’s final approach speed and deceleration profile) for keeping the right distance have also been identified. 

TBS uses a new Human-Machine Interface (HMI) for delivering the required separation minima between aircraft. The Human-Machine Interface displays customised information for approach and control towers. Target distance indicators are displayed on the extended runway centreline of the final approach controller’s radar display and the tower runway controller’s air traffic monitor display.


TBS brings numerous benefits for airports, airlines and passengers, including: 

  • Increase of resilience of runway throughput and efficiency, due to space reduction between aircraft in strong headwind conditions while maintaining the same safety levels;
  • a reduction in delays, cancellations and consequent operating costs;
  • shorter overall flight times;
  • advanced information for controllers, as TBS needs wind profile measurement in the final approach area and this information can be used by the controllers;
  • a global reduction in workload, thanks to the new HMI.


Validating SESAR Time-Based Separation concept

Vincent Treve

Runway Throughput & Wake Project Manager
+32 (0)2 729 5197