Very well and swiftly edited/deleted, Mr Higgins.
Like your friends at Allegheny Tower, I have never
ever denied anyone a clearance in my entire career.
I have
often used the phrase "clearance not available, remain outside control area", followed by some sort of expectation, as a means of ensuring:
- That the pilot understands that they do not have a clearance yet.
- That they have a positive instruction as to what to do in the event that no cleraance is issued (e.g. radio fail etc.)
- They understand that a clearance will become available.
Whilst some pilots - of the less than professional variety - seem to take this as evidence of obstructionism, the smarter ones understand it for what it is.
It is akin to the procedural/non-radar device of issuing a clearance limit. I have used this technique on occasion when it will afford the most expeditious means of providing separation
without delaying either aircraft. It assures that
if, for example, vertical separation does not exist at the time you reach your clearance limit, then you will hold to ensure separation, but I do not expect you to have to do so. As with denying a clearance , I have
never had an aircraft hold at their clearance limit point.