Teacherjh wrote:

S&R is started when you don't arrive.


Well, here's the detail I'm looking for: How do they know you don't arrive -
they have to be told that you will. How do they know when you will arrive -
they have to be told the time to expect you. So, "some time" goes by and you
haven't arrived. S&R is started.

How much time is "some time"? (I'm not asking for an exact number - I'm well
aware that it may not exist).

If the tower has a flight strip printer and no radar you know exactly
when he will arrive because of the time printed on the strip. At about
ten miles out the center will tell that aircraft to contact tower. If
you don't contact tower at or before your expected landing time the
tower will call the center and ask about the aircraft. It will become
immediately clear during that conversation where the airplane is. If
the tower has no printer the center will call the tower with all
inbounds and give the same time as the computer would have.



And the "action" in this case is being told that you will arrive, and "some
time" going by without an arrival. Yes?

Yes.