Monthly statistics are produced for 3 night-time, key performance indicators (KPI) for Heathrow, Gatwick and Stansted; CDA is one of those KPI. It is particularly sensitive at Heathrow because of the Westerly approaches being over central London. However, during the early morning period (06:00) CDA tend to be less accurately applied in order that simultaneous approaches to both runways can be safely delivered. (When the final director is landing traffic at rates in excess of 50 per hour it is far safer to turn in using vertical separation. That means one side cannot have a full CDA.) It is a question of delivering the required capacity.
Point 4
Last edited by 120.4; 6th Oct 2006 at 10:56.
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