S and T
I will try to explain some things.
Wake vortex spacing in the context that Andrew 120.4 was describing is only applied in the Final Approach phase. That is from the Final approach fix to (in the UK at Heathrow) 4 DME from touch down.
The spacing is only to be applied to aircraft that are flying an instrument approach. However, if an aircraft is making an IFR approach and is operating visually under the reduced separation in the vicintiy of the aeiodrome rules, the spacing becomes a recommendation. Some of the spacing at Heathrow is done under the reduced separation criteria. So the question was how many of the 20% were operating under the reduced separation in the vicinity of the aerodrome criteria. But I am sure that 120.4 would know about that rule so I didn't elaborate.
As for the question on intermediate approach, it is well known that 120.4 believes that vortex wake separations should be applied outside of the requirements of MATS pt1 to an area of the intermediate approach. Final approach is considered to be from the Final approach fix where specified, or from the completion of the base leg turn to final where one is not.
The final part of his post on legal minima for the landing is an interesting one and I am not sure if he is saying that the aircraft have not got a landing clearance prior to touchdown or not. If he is then the Heathrow tower controllers would be better able to answer that as that is a completly different area to the one of 120.4's current expertise.
Last edited by zkdli; 22nd Mar 2008 at 22:10.
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