(Corky Scott) wrote in message ...
On Tue, 28 Oct 2003 17:57:43 -0500, "Ron Natalie"
wrote:


"Judah" wrote in message ...
What about a transition clearance?

There ain't no such thing.

So when the guys in the choppers call up Lebanon tower up here in NH
and request clearance through the class D airspace, they're just being
thoughtful?

No, they're missing a critical distinction between a requirement
to communicate, and a need for clearance.

They're required to communicate, and to follow any ATC instructions
or obtain amendment (true of any airspace, E included). But *clearance*
is not required.

"Whatsits Tower, Grumman 12345"
"Grumman 12345, Whatsits tower, go ahead" is all the permission I
need to enter the class D. Of course, part of communicating is
telling someone what you want, so I'm going to say "request transition
NE to SW at 2 thousand five hundred".

Without that call, they'd be cruising through the traffic pattern at
500 feet unannounced. That's straight over the runways. It happens
fairly regularly, and they call in and ask permission every time.

What am I missing?

That it's not a clearance. The VFR tower isn't providing any services
besides separation on the runway and traffic advisories as able. They
can not issue a vector. They aren't providing radar services. They
aren't providing separation in the air.

When you're cleared to enter the Class B airspace, along with that
clearance comes an *obligation* on the part of ATC to separate you
from other traffic, and an obligation on your part to comply with
specific headings and altitudes (so that you can be separated).
When you're cleared for an approach, or given an IFR clearance, again,
both sides assume obligations.

That's the difference and IMO it's not a trivial one.

Cheers,
Sydney