Steven,

Once told to memain clear you must remain clear until the controller
issues an instruction that permits entry.

I sort of thought that when the controller called me by tail number
and said radar contact (and didn't say remain clear), that would
constitute a communication that permits entry. But you wrote:

... entering without an explicit instruction that
permitted entry, such as "proceed on course" or "fly heading xxx", would be
a violation ...

What determines which communications permit entry? Can you point me
to a reference in the FAR or AIM? Do say "proceed on course", but how
is that an explicit instruction to enter the class C airspace? I
would think "cleared to enter class C airspace" would be an explicit
instruction, but I certainly never hear that because I didn't think
that was necessary for class C, only class B. I don't understand why
you think "proceed on course" is an explicit instruction that permits
entry. (It certainly wouldn't be explicit if we were talking about
class B.) Again, a reference to something that would help be know
exactly which communications constituted explicit instruction to enter
vs. not would help me for the future.

John Gaquin wrote:

When you're talking about airspace entry, etc., pilot/controller interaction
is *never* "understood", or "presumed". Clear and direct statements are
used.
....
When you hear the phrase '....cleared to enter...', or '....cleared
into...', or some such.
I keep my airplane at a class C airport and don't think I ever hear
that type of language. When the controller calls my tail number and
doesn't tell me to remain clear then it means that I can enter.

John Harlow wrote:
Lol - in my experience, either the airspace is too busy - or you sound
like you could be a nuisance.
I think it might be standard practice for this AFB. I don't think the
airspace was busy. I guess they don't want people flying in until
they can see them on their screens. I hope I didn't sound like a
nuisance.

John Harlow wrote:
When you explicitly get permission to enter.
I though when they called my tail number and didn't tell me to remain
clear that was permission. Where is what I need to hear defined in
the FAR or AIM?

Maule Driver wrote:
Did the controller contact the pilot after departure before the pilot
called himself?
The controller called me (my speculation is that he called me upon
seeing me on his radar).

Nathan Young wrote:
Irrespective of regulations - it never hurts to ask the controller for
clarification.

I agree with you, but at the time it didn't occur to me that I needed
any clarification. I heard my tail number and did not hear another
remain clear and thought that meant I could enter. The ONLY reason
that I questioned this was that my pilot friend who was on board
questioned it first. And he said that he honestly didn't know, but
believed that I should have heard something else before entering.
Yes, I ask when I am confused about something ... but only if I
realize that I am confused. :-)
Anyway I prefer to get straightened out on these things on the ground
when possible so that I don't have to continually quiz the controllers
about things that I'm expected to know while in the air.

Steven P. McNicoll:
It ends upon receipt of ATC instructions that permit entry.

Which are defined where?

Thank-you!