The key principle of the Time Based Separation (TBS) concept is to define the minimum in-trail distance separation to apply, as a function of headwind, to maintain a constant time separation, as observed in low headwind conditions, consequently maintaining the landing rate.

Under strong headwind conditions the ground speed of the aircraft reduces, whilst wake decay is more rapid. This means that the distance based separations are overly conservative in such conditions.

The application of TBS will help prevent the loss of runway arrival capacity that typically occurs under strong headwind conditions. This is achieved by replacing distance based separations by time intervals equivalent to the distance separation in low headwinds. By doing so, the reduced approach separation recovers most of the lost capacity from headwinds.

London Heathrow have implemented TBS in spring 2015; at least 16 other airports have committed to deploying by 2024.


  • Guidance material and studies


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