Two airspace classes for one airspace? (KOQU)

[John R]

Quonset State (RI) airport (OQU) has class D airspace and is just
south of Providence (PVD), which has class C airspace.

The northern arc of the Class D airspace isn't charted with a
dashed blue line, so the best I can do is assume that this
boundary is coexistent with the Class C surface area. Some of
the class D airspace is under Class C with a floor of 1700 feet,
some under Class C with a floor of 1300 feet, and some is outside
the Class C airspace. To make things confusing on the chart, the
dividing line between the 1700' floor and 1300' floor is beneath
the [25] Class D ceiling symbol.

So according to the chart, the Class D airspace extends to 2500
feet. However, Quonset tower was sternly warning pilots the
other day that their Class D only went to 1300 feet and not to
exceed that without the blessing of Providence. So why does the
chart say 2500 feet for the Class D inside the Class C ring?

This airspace looks pretty confusing. For good measure there is
a class E surface area for a PVD approach under the Class C
ceiling inside the Class D ring, although we can assume that the
E is only in affect inside the D circle when Quonset tower is
closed. To be sure, the tower at Quonset keeps funny hours
somewhat (e.g. closed Mondays).

[G. Burkhart]

"John R" > wrote in message ...
> Quonset State (RI) airport (OQU) has class D airspace and is just
> south of Providence (PVD), which has class C airspace.
>
> The northern arc of the Class D airspace isn't charted with a
> dashed blue line, so the best I can do is assume that this
> boundary is coexistent with the Class C surface area. Some of
> the class D airspace is under Class C with a floor of 1700 feet,
> some under Class C with a floor of 1300 feet, and some is outside
> the Class C airspace. To make things confusing on the chart, the
> dividing line between the 1700' floor and 1300' floor is beneath
> the [25] Class D ceiling symbol.

I may be wrong, but looking at the sectional at
http://map.aeroplanner.com/mapping/chart/eaachart.cfm?chart=Sectional&typ=APT&txt=OQU I
think the (small) area outside the Class C ring that's Class D has the
ceiling of 2500. The Class C floor starts at 1700 over the airport. This
looks similar to Wiley Post airport (PWA) near OKC (Class C) which has [38]
listed as the Class D ceiling outside of the Class C ring and the floor of
Class C above the airport is 2500. When I did my training at PWA, we were
told to stay below 2500 when coming into PWA from the North or West to avoid
the Class C.

Check with the locals, especially ATC for both and they will know and give
you the answers to their airspaces.

[Peter Duniho]

"John R" > wrote in message ...
> [...]
> So according to the chart, the Class D airspace extends to 2500
> feet. However, Quonset tower was sternly warning pilots the
> other day that their Class D only went to 1300 feet and not to
> exceed that without the blessing of Providence. So why does the
> chart say 2500 feet for the Class D inside the Class C ring?

Because that's what they write at all the Class D airports, as near as I can
tell. They just look at the airport elevation, add 500', and put that on
the chart.

We have several Class D airports in our region that underlie the SeaTac
Class B airspace. All have letters of agreement with the SEA approach
facility reducing their Class D ceiling. In one case, the Class D ceiling
is the Class B floor (BFI), and in the other cases, the reduced ceiling of
the Class D either creates or expands a charted Class E area between the
Class D and Class B airspace. The situation around BFI sounds most similar
to yours, where the charted Class D overlaps with the Class C airspace.

Frankly, I find the whole thing very confusing. In the case of BFI, it's
(almost) clear, because the floor of the Class B is clearly marked as being
below the marked ceiling of the Class D. You know (that is, you can assume)
you're either in Class D or Class B, and it's very clear where the Class B
ends. But in the other cases, it's not clear at all if what's really going
on is that the airspace ceded to the SEA approach facility winds up being
Class E, or if it's Class D or Class B (and controlled by SEA App/Dep either
way).

I have always treated the ceded airspace as Class E and no one has ever
taken me to task, even when I was on a tower frequency. So I presume that's
fine to do. But the whole situation highlights the incredibly poor degree
to which these letters of agreement and related arrangements are
communicated to the pilots that they affect.

Pete

[Steven P. McNicoll]

"John R" > wrote in message ...
>
> Quonset State (RI) airport (OQU) has class D airspace and is just
> south of Providence (PVD), which has class C airspace.
>
> The northern arc of the Class D airspace isn't charted with a
> dashed blue line, so the best I can do is assume that this
> boundary is coexistent with the Class C surface area.
>

The "northern arc" isn't charted because that area which would otherwise be
Class D if the PVD Class C airspace was not there is always Class C when the
OQU Class D airspace is in effect.


>
> Some of
> the class D airspace is under Class C with a floor of 1700 feet,
> some under Class C with a floor of 1300 feet, and some is outside
> the Class C airspace. To make things confusing on the chart, the
> dividing line between the 1700' floor and 1300' floor is beneath
> the [25] Class D ceiling symbol.
>

Yeah, one would think they could have done a better job of symbol placement.



> So according to the chart, the Class D airspace extends to 2500
> feet. However, Quonset tower was sternly warning pilots the
> other day that their Class D only went to 1300 feet and not to
> exceed that without the blessing of Providence. So why does the
> chart say 2500 feet for the Class D inside the Class C ring?
>

The standard ceiling for Class D airspace is 2500 AGL, but it's charted in
MSL values. Since field elevation at OQU is just 18 MSL they're the same.
Due to the hierarchy of airspace, the OQU Class D airspace reaches 2500 MSL
only outside the ten mile PVD Class C ring. Inside the ring the Class D
ceiling is the floor of the overlying Class C airspace.

[Steven P. McNicoll]

"Peter Duniho" > wrote in message
...
>
> Because that's what they write at all the Class D airports, as near as
> I can tell. They just look at the airport elevation, add 500', and put
that
> on the chart.
>

So where are some of these airports where the Class D airspace reaches only
500' AGL?

The standard ceiling for Class D airspace is 2500 AGL, but they are charted
in
MSL values. Since field elevation at OQU is only 18 MSL and airspace is
shown in hundreds of feet 2500 AGL becomes 25 on the chart.


>
> We have several Class D airports in our region that underlie the SeaTac
> Class B airspace. All have letters of agreement with the SEA approach
> facility reducing their Class D ceiling. In one case, the Class D ceiling
> is the Class B floor (BFI), and in the other cases, the reduced ceiling of
> the Class D either creates or expands a charted Class E area between the
> Class D and Class B airspace. The situation around BFI sounds most
> similar to yours, where the charted Class D overlaps with the Class C
> airspace.
>

Controlled airspace is established by legislation and is not altered by
letters of agreement between ATC facilities.


>
> Frankly, I find the whole thing very confusing. In the case of BFI, it's
> (almost) clear, because the floor of the Class B is clearly marked as
> being below the marked ceiling of the Class D. You know (that is, you
> can assume) you're either in Class D or Class B, and it's very clear where
> the Class B ends. But in the other cases, it's not clear at all if what's
really
> going on is that the airspace ceded to the SEA approach facility winds up
> being Class E, or if it's Class D or Class B (and controlled by SEA
> App/Dep either way).
>
> I have always treated the ceded airspace as Class E and no one has ever
> taken me to task, even when I was on a tower frequency. So I presume
> that's fine to do. But the whole situation highlights the incredibly poor
> degree to which these letters of agreement and related arrangements are
> communicated to the pilots that they affect.
>

When classes of airspace overlap, the operating rules associated with the
more restrictive airspace class are applied. Class B airspace is more
restrictive than Class C, Class C more restrictive than Class D, etc. Note
that it is the rules of the more restrictive airspace that apply, not the
more restrictive rule. So for all practical purposes, there is no overlap
of airspace classes, the less restrictive class ends where the more
restrictive class begins.

[Peter Duniho]

"Steven P. McNicoll" > wrote in message
ink.net...
> So where are some of these airports where the Class D airspace reaches
only
> 500' AGL?

It's called a typo. I know it's difficult to see where the "2" should have
gone, so I'll give you a hint: put it right before the "5" in "500".

> Controlled airspace is established by legislation and is not altered by
> letters of agreement between ATC facilities.

Fine.

> When classes of airspace overlap, the operating rules associated with the
> more restrictive airspace class are applied.

As I assumed. That doesn't answer the question I asked though. When a
tower controller tells me that I am no longer their problem but the chart
tells me I'm still in their Class D airspace, does that mean I have to
switch over to the approach facility and talk to them?

Note that I'm not talking about a situation in which Class D overlaps with
some other more restrictive airspace. I'm talking about the situation in
which the ceiling of the Class D controlled by the tower has been lowered by
some letter of agreement, but where there was already an area of Class E
between the Class B and Class D. For example, a TIW I recently learned that
the tower controller there only is responsible for traffic up to 2000' MSL,
but the Class B doesn't start until 6000' MSL (3000' MSL north of the
airport, but within the lateral limits of the Class D). The Class D as
charted goes up to 2800' MSL.

Since you say that controlled airspace is not altered by LOA, that implies
that the airspace up to 2800' MSL is still Class D. But the TIW control
tower has said they don't have responsibility for that portion of the Class
D. On the other hand, I was not given a handoff as I climbed through the
top, and by the time I managed to actually get Seattle Approach on the radio
with my particulars, I'd have flown out the side of the airspace.

Am I really legally required to contact the approach facility given
responsibility for that portion of the Class D airspace? I have never done
so, I have never had ATC complain about it, and given the usual busy-ness of
the approach frequencies, it would be impractical to have to deal with them
for the brief period of time one would spend in "their" portion of the Class
D.

Pete

[Neil Gould]

Recently, John R > posted:

> Quonset State (RI) airport (OQU) has class D airspace and is just
> south of Providence (PVD), which has class C airspace.
>
> The northern arc of the Class D airspace isn't charted with a
> dashed blue line, so the best I can do is assume that this
> boundary is coexistent with the Class C surface area. Some of
> the class D airspace is under Class C with a floor of 1700 feet,
> some under Class C with a floor of 1300 feet, and some is outside
> the Class C airspace. To make things confusing on the chart, the
> dividing line between the 1700' floor and 1300' floor is beneath
> the [25] Class D ceiling symbol.
>
> So according to the chart, the Class D airspace extends to 2500
> feet. However, Quonset tower was sternly warning pilots the
> other day that their Class D only went to 1300 feet and not to
> exceed that without the blessing of Providence. So why does the
> chart say 2500 feet for the Class D inside the Class C ring?
>
> This airspace looks pretty confusing. For good measure there is
> a class E surface area for a PVD approach under the Class C
> ceiling inside the Class D ring, although we can assume that the
> E is only in affect inside the D circle when Quonset tower is
> closed. To be sure, the tower at Quonset keeps funny hours
> somewhat (e.g. closed Mondays).
>
Some of the charts can be confusing, but as a matter of practicality, if
you're flying in that area, you'd best be talking to ATC anyway. When I
flew to Martha's Vineyard, my planned course was to go south of PVD and
over Newport. Due to a lot of traffic and meat bombs at Newport, I was
vectored north, then around quite a bit. That neck of the woods can get
pretty busy!

Neil

[Steven P. McNicoll]

"Peter Duniho" > wrote in message
...
>
> It's called a typo. I know it's difficult to see where the "2" should
> have gone, so I'll give you a hint: put it right before the "5" in "500".
>

Consider proofreading.


>
> As I assumed. That doesn't answer the question I asked though.
>

You hadn't asked a question.


>
> When a
> tower controller tells me that I am no longer their problem but the chart
> tells me I'm still in their Class D airspace, does that mean I have to
> switch over to the approach facility and talk to them?
>

What problem is there to be solved? What's the situation?


>
> Note that I'm not talking about a situation in which Class D overlaps with
> some other more restrictive airspace. I'm talking about the situation in
> which the ceiling of the Class D controlled by the tower has been lowered
> by some letter of agreement, but where there was already an area of Class
E
> between the Class B and Class D. For example, a TIW I recently learned
> that the tower controller there only is responsible for traffic up to
2000' MSL,
> but the Class B doesn't start until 6000' MSL (3000' MSL north of the
> airport, but within the lateral limits of the Class D). The Class D as
> charted goes up to 2800' MSL.
>
> Since you say that controlled airspace is not altered by LOA, that implies
> that the airspace up to 2800' MSL is still Class D. But the TIW control
> tower has said they don't have responsibility for that portion of the
Class
> D.
>

Non-approach control towers don't have any actual control over the Class D
airspace unless it is delegated to them by the overlying approach control or
center. A letter of agreement may give them responsibility and authority
for SVFR operations, or for silent departures of IFR aircraft, as examples.
For VFR operations there's not much for them to be responsible for, as no
separation is provided to VFR aircraft in Class D airspace. They may
specify runway, direction of traffic, aircraft to follow, etc., for the
purpose of providing runway separation. That and traffic advisories are
about it for VFR operations.


>
> On the other hand, I was not given a handoff as I climbed through the
> top, and by the time I managed to actually get Seattle Approach on the
> radio with my particulars, I'd have flown out the side of the airspace.
>

A handoff is a radar function, I believe you mean you were not directed to
contact Seattle approach. Sounds like you were departing VFR, so there'd be
no reason for tower to tell you to contact them. If you want radar
services, you call them. If you don't want radar services, you don't call
them.


>
> Am I really legally required to contact the approach facility given
> responsibility for that portion of the Class D airspace?
>

No. If you're IFR you'll be told to contact them, if you're VFR there is
nothing they are responsible for.

[Newps]

> "Peter Duniho" > wrote in message
>
> >
> > When a
> > tower controller tells me that I am no longer their problem but the
chart
> > tells me I'm still in their Class D airspace, does that mean I have to
> > switch over to the approach facility and talk to them?

No. We will often terminate aircraft before they reach the boundary of
class C airspace because the pilot asks to be terminated. If there's no
traffic for you we'll let you go.