Without wishing to start a bun fight...
Twice in the last two days I have been forced to reposition traffic already established on the final approach, because the traffic ahead has slowed below its assigned speed.
In both cases the lead aircraft was heavy and if a heavy slows down before instructed it will nearly always lead to a loss of votex separation behind it, which we are legally required to resolve. I recently saw a video of an incident where the poor guy lost separation between two aircraft on base leg because he was trying to sort out a loss of vortex spacing on final, caused by traffic slowing down. The Final Director's r/t is often saturated and we don't have time to be doing this!
I like to think that we are sympathetic to your energy management needs and thankfully, it is quite common now for traffic to advise us early of a specific speed requirement. As a general rule we know that B757s are slow inside 4 and that B773s & MD11s are quick; we know that the A319 is slippery and difficult to slow down but if you cannot deliver the assigned speed you have got to tell us.
Heathrow is operating at the limit and this is all the more reason why you must obey the speeds; capacity depends on it.
Finally, for those who are not yet aware, we now get a mode S readout of your Indicated and Ground speeds. If you cheat, we know it is you and not the other guy. I am sorry to be moaning here but I have had enough of it. Tonight I went into paper work over it and from now on, he who slows down goes-around.
Please!
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