From: barney@sol.usc.edu (Barney Lum)
Newsgroups: rec.aviation
Subject: Re: Controlled airspace
Date: 30 Jul 1992 21:18:04 -0700
Organization: USC University Computing Services, Los Angeles
NNTP-Posting-Host: sol.usc.edu
Summary: Controlled Zone? Uncontrolled Tower?


Taken from _AOPA_Aviation_USA_, 1991, pg 713-716...  info probably
also found in the AIM:

Uncontrolled Airspace:
   Airspace not designated as continental control area, control area, 
   control zone, TCA, PCS, ARSA, or transition area is considered 
   uncontrolled airspace.  Air traffic control (ATC) does not have the 
   authority or responsibility to exercise control over air traffic within 
   this airspace.

Controlled Airspace:
   Airspace designated as continental control area, control area, 
   control zone,  TCA, PCS, ARSA, and transition area is considered 
   controlled airspace [reference to illustration] .  Air traffic within
   controlled airspace may be subject to ATC.

  [definitions of the above airspaces omitted]

Special-Use: (Prohibited, Restricted, Warning, Alert, and MOAs)

*OTHER* Airspace:
   Airport Traffic Areas, Airport Advisory Areas,  Military Training Routes

----------
As seen from above, an ATA is uncontrolled airspace :]. But, ATC
"authorization" is still required to operate in it.  
(Or does it being "other" render it as neither?)

The control zone is to protect IFR traffic when the airport is 
below VFR minimums,  and a weather observer is required for it.

Much of the confusion probably comes from the term "Controlled"
airport.  Perhaps "Towered (operating!)" and "Non-towered" would 
be more accurate.  It's also a bit less frightening to the
occasional passenger :).

An interesting illustration of the difference between an ATA and
CZ might be the following (assuming my understanding is correct :) )..

Let's say a pilot at Whiteman, CA calls visibility to be 1 mile in 
smaze (no observer there, no official weather info, no CZ, no Special 
VFR [needed], just the friendly tower-folk).  It appears that he can 
take off using VFR minima for "Outside controlled airspace" which for 
daytime, is one mile and clear of clouds.  

He calls the tower and can climb up to 1200 AGL, but must stay VERY 
close to the airport to avoid the CZ's of Van Nuys and Burbank 
surrounding its southern boundaries (no 700' transition area over WHP).  
Our intrepid aviator can now depart to the north, dodging "obstacles" 
before meeting up with cumulo-granite in about two minutes.  Or, maybe 
he'll be lucky and find three miles vis at 1199 AGL then *see* the hill
he's about to hit :b.  If he makes it through all that, maybe he'll 
then give Burbank Departure a call :).

The soon-to-be alphabet soup scheme combines the ATA/Control Zone into 
one.  If one or the other  or both exist, it'll become Class-D.  This
might help take out the ambiguity of "controlled airspace" from ATA's 
and Airport Advisory Areas (Non-Towered with an observer [and 
control zone] ). 

Looks like the days of "Controlled but Uncontrolled" (towered, but 
no control zone) Whiteman and similar airports are winding down.
Not to leave them out, non-towered airports with control zones
are in the same situation.

Oh yes.. Class-G, the new "uncontrolled" airspace will no longer
allow "clear of clouds", but require the 500/1000/2000 distance
from them.  Class-B (Current TCA), however, will allow "clear
of clouds in 3 miles vis."  

This makes me wonder.. what sort of limitation might the controller 
impose on the ~VFR pilot?  "Maintain VFR" won't be quite right.. 
"Remain clear of clouds and three miles visibility in the Los 
Angeles Class-B airspace" seems kinda wordy.  Perhaps "Maintain 
Class-B VFR?" :}

The FAA Aviation News - March/April 1992 issue has a nice little
diagram and table comparing today's airspace with ABC.  After looking
at it a bit, it's not that bad.

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