"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/c...yp=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.