Approaches into JNB during this current bad weather

[ACE MAN]

I am sure with that metar the ATIS would have had LVO's (LVPS) in force. When the ceiling , as in that metar, is below 200', it is no longer a cat1 approach, but you can still shoot a cat1 approach as per previous comments above on Vis requirements and ATC cannot enforce the approach ban. When LVO's are enforced greater spacing is required (I am not sure what JNB is these days , an appr specialist could answer that) I think it is 8-12 nm!! - for protection of the localizer sensitive zone etc. Do the math and you will see you can only do about 13-15 arr on one runway in an hour! Any airport in the world suffers the same delays when it comes to LVP's. You can probably do 25ish departures off the departure runway , bringing hourly movements to 35-40 in an hour which is actually impressive during LVO's (LVP's).

[transducer]

Putting aircraft into batches would require precise scheduling by the airlines and even more precise enroute separation to prevent delays and holds, ie. not going to happen. The reality is that all the turboprops you mention can comply with all the maximum speeds allowed in the TMA, bar maybe 250kts for the odd one or two but that is averaged out by nugpot's correct statement that they can decelerate quicker and are thus more flexible in the TMA than a lumbering jet.

Turbo prop aircraft are sequenced quite successfully in the 1st world where some operators have over 50 of a type on a hub and spoke out of major airports. Fancy computer systems that sequence aircraft work just like any computer system and software: rubbish in equals rubbish out. In aircraft that are managed by the FMS/C there is still a human at the end that can shed experience on the matter and select heading mode. I suspect that is the goal with the ATC sequencing software that a human with experience can ask you to go to heading mode and not merely follow the blind instructions of software. I fear my previous statement may be stating the obvious short comings.