Hi BusyB, I didn't explain myself very well. The disadvantage to the tower is that it may increase workload for the ground controller...just one more extra mouth to feed as the taxying from a North arrival back to the freight area involves maybe 6 odd tranmissions and some 10 minutes of taxying compared to one possibly two transmissions after a South runway landing. The freighter becomes a longer part of the traffic scene during the lengthy taxi back, instead of a quick quiet death. Also the South landing freighter does not have to cross an (at times busy) active runway.
Without going into all the sequencing requirements for arrivals, generally arrivals on to the same runway (if not being used simultaneously for departures) are planned at either 5NM or min wake turb, and in (let's call it reasonable wx conditions) we can sequence staggered arrivals between North and South 3NM apart. providing the two Aerodrome Controllers can visually separate the arrivals. So, if we had no departures at all, the most efficient way to run the arrivals would be North, South, North, South etc. Well, we also have departures to consider, and hence the system is basically run as I described last night. It has it's faults at times, I agree, but as an overall way of getting the most departures into the air along with the most arrivals on to the ground, I would think that we are fairly close to the mark. Generally if we have two successive arrivals to a runway that is also being used for departures, the desired sequencing space is 8NM to allow the release of a departure between the two arrivals. This happens with two cargo aircraft on the South runway (two rwys available), or as we are often on RWY07L only from around midnight till 9am the following morning, then all arrivals will normally be spaced to allow departures off the North runway. Bearing in mind that the bulk of the departures between 11pm at night and 12.30am are very heavy long haul, I can assure you that we need every bit of 8NM as an inter-arrival spacing.
In relation to your observation that at times you are disadvantaged as a departing aircraft, because of arriving freighters, well, it is probably outside of the "all on the North" period (from 1230pm local to 2000). We have a system in place, and I am not the one about to try and change it. The only people that will be able (maybe) to get that to happen are the users, ie you and your companies. If the operators through here really want all of the freighters landing all of the time on the North runway, well you will need to poll the Airport Authority and CAD to have the system changed. I can bet you anything you like that the two major operators through here, with both Pax and freighter aircraft would say "bugger off". It is interesting that I was talking to a KA captain recently, and he said to me "If I am parking on the South apron, why can't I land on the South runway?" Unfortunately the "me only" syndrome is alive and well!
The bit about offering a runway change to an arriving freighter being some 10 to 15 mins before landing is purely a curtesy. We do have some sensitivities re not changing landing runways once aircraft are too close to landing. If everyone coming in here was a space cadet and the ace of the base, then it might be a bit more easy to throw things around, however this is not the case. Where do we draw the line? At times it can be a bit conservative, but I guess we have a "weakest link in the chain" that we have to pander to at times.