"Teacherjh" wrote in message
...

To give meaning to the part that says "by the time forwarded to
the tower".


Explain.



The tower is sent an "expect arrival at 5:34". At 5:36 the plane arrives.
What is different about the two minutes after 5:34 compared to the two
minutes before 5:34? Just that at 5:34, 5:34 happened, and that is
special because it is an expected arrival time that was not
consummated.

So, at least in somebody's mind, an alarm went off at 5:34. No?


No. An airplane that had been estimated to land at 5:34, but didn't
actually land until 5:36, would be on tower frequency by 5:34, so the tower
would know where it is.

If the forwarded estimate was off by more than three minutes the facility
providing IFR services would revise the estimate.




That is, unless what you mean is that a search begins any time a
handoff fails under IFR. This is another reasonable interpretation,
when "handoff" is expanded to include "expected position report".


I mean what I wrote, a handoff is a radar function and has nothing to do
with it.



But then, each ETA (EPRT) would function as the "alarm" I am
talking about... getting reset every time.

Is this pretty much the way it happens?


Estimates are revised regularly. Sometimes they just take the form of a
time change at a specific fix, sometimes a new strip is generated.