"Jim Macklin" wrote in message
...

It isn't just the traffic ON the runway, but the traffic in
the air within many miles that has to go somewhere.


The traffic ON the runway can depart, probably a good many that have already
taxied for departure can also depart. You don't have to shut down all
operations immediately for an emergency aircraft that needs to land against
traffic but is still some 80 miles or so away.