V1
Experience in the UK has shown that it is beneficial to vary from the ICAO wake turbulence separation standards.....the UK uses 4 rather than 3 categories generally. Consider the need to maximise runway utilisation at a busy airport such as Heathrow which is bursting at the seams capacity-wise...and which is almost unique in the UK for dual runway operation. Whereas Approach at a single runway operation might use "gaps" to get departures away, Heathrow has a dedicated arrival runway. In order to maximise landing efficiency there is a unique sub-categorisation for wake separations.....for example "upper medium".....this allows a phenominal increase in landing rate whilst still providing adequate safety. I don't do Heathrow Approach except in abnormal circumstances.....hopefully one of our Heathrow colleagues can correct any errors that I've made....and elaborate further on the categories. You can appreciate how vital it is to know exactly which type and/or model of aircraft you are flying. VISIT US AND SEE!!!!