"Mark Hansen" wrote in message
...

How long will it take the aircraft to go from requesting the clearance
(or taxi) and being ready to take off?


Depends how far it has to taxi. The controller will know from experience
and provide an appropriate estimate to the facility providing departure
control functions.



The tower needs to negotiate a
slot in the system for your flight. To do that, it needs to know when
you're going to be ready to go.


The tower knows where you are and where you have to taxi to and how long it
takes to get there.



Yes, as explained above.


Well, you were taught wrong.