Greg Esres wrote:

They are either canned from the LOA with the IFR facility, relayed
verbatim from the IFR facility (4-2-4), or the tower controller is
trained, certified, and delegated the authority by the appropriate
level of management to use the tower radar display to issue them
(3-1-9c).


Exactly. In the first case, the tower is not capable of tracking the
aircraft with respect to obstacles, and therefore cannot provide any
terrain clearance, which is why they can't vector.

No, many approach control facilities will have an LOA with a tower to
send the departures out on canned headings not for terrain but for
operational needs. Take a busy airspace like Minneapolis. MSP TRACON
will have an LOA with the four towers in their airspace. What they can
do is tell each tower that you can automatically release IFR departures
but they have to be on certain headings, these headings will guarantee
separation from all other IFR traffic in the area. Each faciltiy wins
in this deal. TRACON doesn't have to constantly answer the landline to
issue releases and tower doesn't have to call all the time.