Teacherjh wrote:



Rather than explain, let me ask how a search is begun for an aircraft that does
not land when it is expected to.

If you don't call in to cancel your flight plan then S&R is started.


Say you hand off to the tower, and the
aircraft does not contact the tower.

Happens every day. Lots of times I'll just let you land without a
clearance. You'll never do that again.


The plane is below radar. A few minutes
go by, then a few more, and still no contact. Perhaps the airplane has been
abudcted by aliens, or has crashed in the forest, or has had an electrical
failure, or the nut behind the yoke came off. So, what happens? When?
Triggered by what? Why?

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



Same question, nontowered.


S&R is started when you don't cancel your flight plan.