Gonzo,
Our MATS 2 states that in order to use the "after the vacating" or "after the landed" cleared to land, the controller must be satisfied that the first landing aircraft will be either vacated or 2500m down the runway before the next aircraft touches down.
In order to be
satisfied of this I need the first aircraft on the runway to check their speed is under control ( for the vacated condition ) or that they haven't slowed down so much that the distance criteria will not be met. I think it's partly a factor of different RET layout and positioning from Heathrow, and partly the mixed mode operation.
When using this type of clearance I normally find that the landing aircraft is between about 1/2 to 1 mile from touchdown which gives 15 to 30 seconds (ish) extra time, and I want to be sure nobody has a chance to interrupt the clearance ( life history syndrome on first contact! ). Additionally in high intensity mixed mode ops my next call is likely to be a conditional line-up which needs to be made so that the departure is a) mentally ready and b) starting to move onto the runway as soon as the arrival is past them. So I don't find any problem with the timing for us. I don't know how your part 2 is worded but for our purposes I don't think I could ever convince myself that I would be genuinely satisfied that our criteria would be met until the first lander is in the roll-out.
To be honest, I'd guess that I probably only use this for a fairly small percent of movements ( about 10 percent at a guess, although it will vary according to the spacing and traffic speeds. )
