Boundaries between Approach/Departure and Center

Thought most all IFR handoffs were automated?
Al


"Ronnie" wrote in message
et...
The Air Traffic Control System Command Center owns all controlled
airsapce in the US. They allocate authority to 21 ATC Centers via letters
of authorization (LOA) that specify the lateral and vertical boundaries of
each
center's airspace. The centers divide their airspace up into high
alititude
and low altitude areas with each sub-divided into multiple sectors. The
laterial
and vertical boundaries of each sector are designed to handle the
particular
geographical area and traffic flows.

Centers delegate authority to the approach / departure radar facilities
(TRACONs)
within their airspace via letters of authorization that define the lateral
and vertical
boundaries of the TRACON's airspace. There are 197 TRACONs in the US as
of
the last time I checked.

TRACONs in turn grant airspace autority via LOA to the tower facilities
within
their airspace. Again, laterial and vertical boundaries are defined in
the LOA.

Handoffs occur when a flight crosses a boundary between facilities or
sectors.
None of the charts show all these boundaries. Sectionals show controlled
airspace
associated with an airport terminal area, but there usually multiple
sectors within a
large TRACON. Low altitude IFR En Route charts show the center
boundaries,
but not the sector boundaries. Frequencies as charted for the various
sectors in a
general area, but these are not always the frequencies that a flight will
be given during
a handoff. Instrument flights deal with this by simply following the
instructions
given by ATC; eg. "N54321 contact Memphis Center on 134.25." We don't
concern our selves about where the boundaries are, because we will be
prompted
during the hand-off. Also, you may be given a hand-off before or after
you cross
an ATC boundary, depending on controller work load, his ability to
coordinate with
the receiving controller, and aircraft speed.

Should you miss a hand-off or get out of range before a hand-off occurs,
simply find
a center frequency or TRACON frequency within range and call to
re-establish
communication. If you are not on the correct frequency, the controller
will get you
to the correct one.



"Mxsmanic" wrote in message
...
What determines the boundaries between airspace managed by an en-route
ATC center and an approach or departure center? I don't see any clear
indication of which is which on sectionals. There are boxes saying
who to contact for approach, but nothing that shows where the handoffs
between terminal control and center usually occur. Is there a general
rule?

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Ronnie writes:

The Air Traffic Control System Command Center owns all controlled
airsapce in the US. [...]

Thanks for the excellent explanation!

Are the boundaries fixed at all times, or can they vary by time of
day, day of week, etc.?

Are the LOAs confidential, or simply not generally published?

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Sam Spade writes:

Good answer. Next question: why isn't all airspace in the United States
controlled airspace?

Why should it be?

The main reason for controlled airspace is to keep aircraft from
hitting each other when they cannot see each other. A lesser reason
is to optimize traffic flow in areas of heavy traffic. If traffic is
not heavy and aircraft can maintain visual separation, they don't need
controlled airspace.

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Mxsmanic wrote:



I was under the impression that Newps has some experience with both
piloting and ATC,


I forget.

They are generally considered confidential, although you may obtain the
information under the freedom of information act.

Viperdoc wrote:

They are generally considered confidential, although you may obtain the
information under the freedom of information act.

They aren't confidential. If they were I would know, some documents and
information is and we are told that. These aren't. It's not really
useful information if I gave you a map of the various boundaries.
Individual sectors within centers and approach controls are combined and
decombined at regular and irregular intervals. Plus any two controllers
can get together and agree to do just about anything for a given amount
of time, thus making any published boundaries irrelavant. We do that
virtually every night with Salt Lake center. The call goes like this,
from the ZLC controller to the BIL approach controller....."Down to 9
til 5?" I answer..."Yep." Thus circumventing months and months of
careful planning and negotiating between untold numbers of high level
management and their staffs. Our letter of agreement states that all
IFR aircraft will be at or descending to 13,000. That's too
constricting so center wants approval to go down to 9,000 and they don't
want to call for each one and I certainly don't want to have to answer a
call for each request. So I could show you many maps of carefully drawn
boundaries but they are almost never used in that manner.

Viperdoc writes:

They are generally considered confidential, although you may obtain the
information under the freedom of information act.

Why are they considered confidential? Are there terrorists eager to
know where one controller's airspace ends and another's airspace
begins?

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Newps:

Sorry, I was sending some poorly disguised cynicism to the village idiot,
hoping he would go away.

I am aware of the LOAs and general ATC structure.

Thanks.
"Newps" wrote in message
. ..


Viperdoc wrote:

They are generally considered confidential, although you may obtain the
information under the freedom of information act.

They aren't confidential. If they were I would know, some documents and
information is and we are told that. These aren't. It's not really
useful information if I gave you a map of the various boundaries.
Individual sectors within centers and approach controls are combined and
decombined at regular and irregular intervals. Plus any two controllers
can get together and agree to do just about anything for a given amount of
time, thus making any published boundaries irrelavant. We do that
virtually every night with Salt Lake center. The call goes like this,
from the ZLC controller to the BIL approach controller....."Down to 9 til
5?" I answer..."Yep." Thus circumventing months and months of careful
planning and negotiating between untold numbers of high level management
and their staffs. Our letter of agreement states that all IFR aircraft
will be at or descending to 13,000. That's too constricting so center
wants approval to go down to 9,000 and they don't want to call for each
one and I certainly don't want to have to answer a call for each request.
So I could show you many maps of carefully drawn boundaries but they are
almost never used in that manner.

Newps wrote:


Viperdoc wrote:

They are generally considered confidential, although you may obtain
the information under the freedom of information act.


They aren't confidential. If they were I would know, some documents and
information is and we are told that. These aren't. It's not really
useful information if I gave you a map of the various boundaries.
Individual sectors within centers and approach controls are combined and
decombined at regular and irregular intervals. Plus any two controllers
can get together and agree to do just about anything for a given amount
of time, thus making any published boundaries irrelavant. We do that
virtually every night with Salt Lake center. The call goes like this,
from the ZLC controller to the BIL approach controller....."Down to 9
til 5?" I answer..."Yep." Thus circumventing months and months of
careful planning and negotiating between untold numbers of high level
management and their staffs. Our letter of agreement states that all
IFR aircraft will be at or descending to 13,000. That's too
constricting so center wants approval to go down to 9,000 and they don't
want to call for each one and I certainly don't want to have to answer a
call for each request. So I could show you many maps of carefully drawn
boundaries but they are almost never used in that manner.

For whatever it's worth, the electronic map provided with JeppView has
center boundaries. Those sometimes can be useful for flight planning
purposes. Sector boundaries have little value to pilots. And, as you
say, approach control boundaries and sectors vary vertically to the
point that is also useless information to a pilot.

Sam Spade wrote:
Newps wrote:


Viperdoc wrote:

They are generally considered confidential, although you may obtain
the information under the freedom of information act.


They aren't confidential. If they were I would know, some documents and
information is and we are told that. These aren't. It's not really
useful information if I gave you a map of the various boundaries.
Individual sectors within centers and approach controls are combined and
decombined at regular and irregular intervals. Plus any two controllers
can get together and agree to do just about anything for a given amount
of time, thus making any published boundaries irrelavant. We do that
virtually every night with Salt Lake center. The call goes like this,
from the ZLC controller to the BIL approach controller....."Down to 9
til 5?" I answer..."Yep." Thus circumventing months and months of
careful planning and negotiating between untold numbers of high level
management and their staffs. Our letter of agreement states that all
IFR aircraft will be at or descending to 13,000. That's too
constricting so center wants approval to go down to 9,000 and they don't
want to call for each one and I certainly don't want to have to answer a
call for each request. So I could show you many maps of carefully drawn
boundaries but they are almost never used in that manner.

For whatever it's worth,

Ditto...

the electronic map provided with JeppView has
center boundaries.

Perhaps the following helps?

http://www.fly.faa.gov/ois/ and in particular
http://www.fly.faa.gov/ois/tier/themap.htm

Those sometimes can be useful for flight planning
purposes. Sector boundaries have little value to pilots. And, as you
say, approach control boundaries and sectors vary vertically to the
point that is also useless information to a pilot.

Regards,
Jon