"Dan Thompson" wrote in message
om...

I've forgotten what the airspace classification is for a Class D airport
with the tower closed that underlies Class B space. Does it revert to E
or what? Is it controlled airpace to the ground?


Class D airspace can become Class E or Class G when the tower is closed.

A surface area requires:

1.) Communications. Communications capability with aircraft which normally
operate within the surface area must exist down to the runway surface of the
primary airport. This communications may be either direct from the ATC
facility having jurisdiction over the surface area or by rapid relay through
other communications facilities which are acceptable to that ATC facility,
such as a FSS.


2.) Weather Observations. Weather observations must be taken at the
surface area's primary airport during the times the surface area is
designated. The weather observation can be taken by a Federally
certificated weather observer and/or by a Federally commissioned weather
observing system.

If the tower is responsible for taking weather observations, then when the
tower closes the airspace must become Class G. If the tower serves as the
rapid communications relay for the ATC facility having jurisdiction over the
surface area, then the airspace must again become Class G when the tower
closes, even if weather observations are still taken by another entity, such
as an AWOS or ASOS.

If communications still exist and weather observations are still taken after
the tower closes, then the airspace can become Class E or Class G. It will
become Class E if necessary to accommodate instrument procedures if such
action is justified and/or in the public interest. The following factors
are among those that are considered:

1. Type of procedure including decision height or minimum descent
altitude.

2. The actual use to be made of the procedure, including whether it is
used by a certificated air carrier or an air taxi/commuter operator
providing service to the general public.

3. The operational and economic advantage offered by the procedure,
including the importance and interest to the commerce and welfare of the
community derived by the procedure.

4. Any other factors considered appropriate.