AA,
To answer your questions about when we clear an aircraft to land it may help to understand what the runway set up is at the airport that I work at.
I work at FWA (
http://fwa.natca.net ) which has 3 runways (5/23, 14/32, and 9/27) all of which intersect each other, the primary runways are 5/23 and 14/32. All aircraft (VFR and IFR) are sequenced by approach. Tower sequences any pattern traffic into the approach sequence without changing or affecting without coordination the sequence established by the approach control.
>Under what circumstances do you do this?
>VMC only?
>IMC?
Both, I can clear an aircraft to land as soon as it is switched by approach. Subsequent aircraft can be cleared to land on initial contact because they are sequenced by approach, but I still must monitor the final to ensure that the subsequent aircraft doesn't overtake the first aircraft.
Basically we are using "Anticipated Seperation". I anticipate that the first aircraft will be clear of the runway (large or heavies) before the next aircraft crosses the landing thresshold.
<Do you do it when the runway is used for departures AND arrivals, or only when, say with parallel RWYs, you use one for departures and one for arrivals
Since FWA does not have parellels we do it all the time.
>Do you do it during crossing runway ops?
Yes, but I must be sure that the first aircraft is through the intersection or if applicable is holding short of the intersection before the aircraft on the crossing runway crosses the landing thresshold.
>Do you do it if the airport layout requires regular runway crossings?
Yes, the majority of the operations at FWA require an aircraft that has landed to cross another runway to get to the ramps.
>Are there specific conditions that must be met before you can do it?
No, again we are using anticipated seperation. As the tower controller I have to monitor the final to ensure that seperation is maintained, even though approach is ultimately responsible for establishing the sequence and seperation on final.
If I have pattern traffic (VFR touch and go) I sequence this traffic in between the traffic that is sequenced to the runway by the approach control. Our SOP mandates that I do nothing that conflicts or affects the seperation on final unless I coordinate with the approach control.
Mike
NATCA FWA