Class D / Class C precedence

Jarod writes:



Newps wrote:

Mxsmanic wrote:

Newps writes:


You can only be in one airspace at a time. At TTD notice the class D
circle isn't a full cirlce. It gets cut off where the class C goes to
the ground.


Yeah, but look at the altitudes. The top of the Class D appears to be
_above_ the floor of the Class C that it overlaps.

The class C does not exist where the class D does.

Are you sure about that? Providence Class C protrudes into Quonset Point
class D airspace and the Quonset Tower is very adamant that the overlapping
area is Class C and requires communication with Providence.

I'm looking at the inset on the Seattle sectional right now. The
dotted line of the TTD Class D doesn't extend into the central part of
the PDX Class C (where the latter starts at the surface). However, in
the two Class C sectors outside that, you see the dotted line of the
Class D, and 25 in a box, indicating that the Class D extends up to
2500 feet inclusive. But those two Class C sectors start at 1700 and
2000 feet, both below the ceiling of the Class D. So is 2000 feet
Class C, or Class D?

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One thing you can be sure of with ATC. Only one controller owns the
airspace at any given time. Those two facilities have gotten together
to iron out the airspace.




Jarod wrote:


Newps wrote:


Mxsmanic wrote:


Newps writes:



You can only be in one airspace at a time. At TTD notice the class D
circle isn't a full cirlce. It gets cut off where the class C goes to
the ground.


Yeah, but look at the altitudes. The top of the Class D appears to be
_above_ the floor of the Class C that it overlaps.

The class C does not exist where the class D does.


Are you sure about that? Providence Class C protrudes into Quonset Point
class D airspace and the Quonset Tower is very adamant that the overlapping
area is Class C and requires communication with Providence.

Roy Smith writes:

That's an odd way to say it. Consider VFR minimums in overlapping Class D
& B airspace (a pretty common occurance for satellite towered airports
under the shelf of a Class B). The Class D rules say "1000 feet above, 500
feet below, 2000 feet laterally" for cloud clearance. The Class B rules
say "clear of clouds". The D rule is more restrictive, but the B rule is
what's in effect.

Zero clouds is less restrictive than clouds a few thousand feet away?

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Mxsmanic wrote:
Roy Smith writes:

That's an odd way to say it. Consider VFR minimums in overlapping Class D
& B airspace (a pretty common occurance for satellite towered airports
under the shelf of a Class B). The Class D rules say "1000 feet above, 500
feet below, 2000 feet laterally" for cloud clearance. The Class B rules
say "clear of clouds". The D rule is more restrictive, but the B rule is
what's in effect.

Zero clouds is less restrictive than clouds a few thousand feet away?

Not "zero clouds", but "clear of clouds". Having to stay away from a
cloud by only an inch is much less restrictive than having to stay
hundreds of feet away.

Kev

Kev writes:

Not "zero clouds", but "clear of clouds". Having to stay away from a
cloud by only an inch is much less restrictive than having to stay
hundreds of feet away.

Ah ... I thought "clear of clouds" meant "[sky] clear of clouds,"
rather than "[aircraft] clear of clouds."

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"Mxsmanic" wrote in message
...
Kev writes:

Not "zero clouds", but "clear of clouds". Having to stay away from a
cloud by only an inch is much less restrictive than having to stay
hundreds of feet away.

Ah ... I thought "clear of clouds" meant "[sky] clear of clouds,"
rather than "[aircraft] clear of clouds."

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Class B is more "restrictive" in the sense that you need an ATC clearance
before entering... Class D all you need to do is establish two way
communication.

"Wade Hasbrouck" wrote in message
...

"Mxsmanic" wrote in message
...
Kev writes:

Not "zero clouds", but "clear of clouds". Having to stay away from a
cloud by only an inch is much less restrictive than having to stay
hundreds of feet away.

Ah ... I thought "clear of clouds" meant "[sky] clear of clouds,"
rather than "[aircraft] clear of clouds."

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Class B is more "restrictive" in the sense that you need an ATC clearance
before entering... Class D all you need to do is establish two way
communication.

And when I say "establish two way communication" I mean you call them up and
if they acknowledge you in any way other than telling you to "stay out", you
are allowed to enter the Class D. i.e. if I call "Renton Tower, Cessna
1538V, Downtown Bellevue with Echo to land", and they reply with "Cessna
1538V, standby", that is considered establishment of two way communication
and I am allowed to enter the Class D. If they don't respond, then I must
stay clear of the Class D.

In your simulator you will never run into this.

One time going from Bremerton (PWT) to Boeing Field (BFI), as I came up on
the North end of Vashon Island, a guy departing BFI had declared an
emergency. The radio was quiet and thought I would see if the Boeing
Controller would acknowledge me (hoping for a "standby") so I could enter
the Class D, and so I called "Boeing Tower, Cessna 738VJ, North Vashon, with
Sierra, to land", and I got no response, so I started a left 360... then
the radio chatter picked up for the emergency and others inbound, and
between about 1/4 the way through the 360, the controller basically told
everyone, "I have an emergency in progress, I will get to as soon as I
can...", just past 1/2 way through the 360 the emergency was over and the
controller had gotten back to everyone but me and asked "is there anyone I
need to talk to that I haven't yet", suspecting he missed someone, and it
was me, but figured I would wait until I was pointed roughly in the right
direction before calling him again. Got pointed east, and gave him a call,
and he thanked me for my paitence. I had to do the 360 to stay out of the
Class D, as I had not yet established two way communication.

Communications with a troll are found to enable their behavior.

Andrew Sarangan writes:

An obvious example of this is restricted airspaces. The majority of
R-airspaces overlap with G or E airspaces, but in those instances we
don't question which rules apply.

They aren't airspace classes though. Class B and Class C are both
airspace classes; logically they cannot occupy the same space at the
same time.

Restricted and other special airspace is an additional qualifier that
supplements the existing airspace class, so they can coexist.

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