Brian, have a look at NATS.aero/tbs
TBS v1 took the UK 6 category wake separation that you would recognise, and used that distance as a baseline for a headwind of 5kts. This is then translated into time separation, for example 90s for a 4nm separation.
The TBS tool calculates the headwind component on final approach by using the Mode S data downlinked from each aircraft.
It then calculates what distance would result in a 90s gap given current headwinds. So in a 15kt headwind, it might be 3.5nm, in a zero wind day it might be 4.3nm.
An indicator is then depicted on radar 3.5nm or 4.3nm behind the leader of the pair in question for FIN to reference.
Yes, you read that right, if the wind is less than a 5kt headwind, we actually increase separation over the distance based separation.
Only wake separations we’re provided with indicators.
TBS v2 incorporated RECAT (RECATegorisation of wake)....so 757, 767, A300 are what is effectively a ‘lower heavy’ category, and their new separations.
it also incorporates Optimised Runway Delivery, which forecasts the expected compression between the pair of aircraft based on average speed profiles inside 4DME, so FIN sees an indicator which is threshold separation + compression, and Tower sees an indicator at threshold separation only.
TBS v2 is also doing the same in terms of modifying according to headwind component.
TBS v2 also provides indicators for certain pairs where runway occupancy is greater than wake separation, or where wake separation requirement does not exist.
Hope that makes sense!