FAA: class D if tower closed

[Heli+]

Hello,

one of the simple questions again turns out to be really difficult:
What precisely happens to a D or C airspace if the tower is closed?
The AFD says "other times CLASS G", for some C it even says "other time CLASS G, CLASS E 700 AGL and above".
While the latter is pretty clear, the D bothers me. What is the ceiling of G replacing D at night? Is it 700AGL or 1200AGL or the ceiling of D during the day (which is 2500AGL).
Where is this quite important information written down? I couldn't find anything in the FARs or AIM.

Also, what happens to an attached class E surface area? It would be weird if the E sfc area remains effective while the D "core" itself becomes G.

[BigGrecian]

Ask your instructor!
The short answer is use the legend on the chart.
The Class D become Class G airspace from whichever altitude the Class G normally goes upto.

If you look at the chart the majority of the Class D airfield have the shaded magenta lines around them indicating Class E begins at 700', so in that case Class E would begin at 700' (Class E normally begins at 14,500' MSL)

The Class E stubs however, I believe stay as Class E as

Extension to a surface area.
There are Class E airspace areas that serve as extensions to Class B, Class C, and Class D surface areas designated for an airport. Such airspace provides controlled airspace to contain standard instrument approach procedures without imposing a communications requirement on pilots operating under VFR.

Therefore, it is for separation and may be being used by another authority such as a centre for IFR traffic which may be going into the airfield, even if it is shut.

[Heli+]

We discussed that topic but ended up with some confusion. We have agreed what you described is most likely right. But I can not find that in any regulation or even books. However it must be written somewhere.

The (sectional) chart legend doesn't help much! Have a look yourself. Nothing about inactive control zones.

[BigGrecian]

Your over complicating the issue.

Class Delta is defined as
Generally, that airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower.

If the Control Tower is not active then the class D is no longer valid; therefore that airspace and any associated stubs become whatever airspace as designated by the chart....

Using your chart - work out what altitude Class E starts at. The AIM states that Class E starts at 14,500' unless otherwise specified.

(Look over the ocean, in FL there is a line about 8nm of the coast indicating Class E begins at 1200')

Most airfields have the magenta shade around them indicating this Class E would begin at 700'.
The regulations, don't and will never show every circumstance, in the same way an instructor can't teach you everything you will ever need to know about how to fly. Some information has to be deduced given certain regulations and facts.

If your instructor doesn't know, he should be asking a colleague who does.

Note my edit on my first post RE : Class E stubs...